WO2025164570A1 - Drive measurement circuit, impedance measurement device, impedance measurement system, and drive measurement method - Google Patents

Abstract

A drive measurement circuit (2) comprises: a current measurement unit (21) that measures the current of a first battery (B1) and the current of a second battery (B2); a voltage measurement unit (20) that measures the voltage of the first battery (B1) and the voltage of the second battery (B2); an AC detection unit (22) that receives a measurement instruction signal including information on a measurement frequency from a host system (200) that has a function of calculating the AC impedance, and measures an AC voltage and an AC current corresponding to the measurement frequency and outputs the AC voltage and the AC current to the host system (200) on the basis of the measurement result of the voltage measurement unit (20) and the measurement result of the current measurement unit (21); and a drive control unit (23) that drives a plurality of switching elements so as to periodically change the movement state of electrical energy via an inductor (14) in accordance with the measurement frequency.

Description

Drive measurement circuit, impedance measurement device, impedance measurement system, and drive measurement method

This disclosure relates to a drive measurement circuit for controlling an impedance measurement device that measures the AC impedance of multiple batteries connected in series.

AC impedance is a parameter used to determine the battery's condition. The impedance measurement method disclosed in Patent Document 1 superimposes an AC current of a first reference frequency onto the battery, measures the battery's voltage and current at a sampling frequency significantly higher than the first reference frequency, and converts them into digital values. Each digital value is then multiplied by the first reference frequency signal and a second reference frequency signal (for example, the first reference frequency signal is a sine wave and the second reference frequency signal is a cosine wave) that has a phase orthogonal to the first reference frequency signal, thereby converting each digital value into the real and imaginary components of the complex voltage and complex current, respectively. The data for each component is then integrated (averaged) to reduce measurement error and retained, and transmitted to a higher-level system. The higher-level system has a CPU that divides the complex current component from the complex voltage component to calculate the AC impedance, and then sweeps the first reference frequency (low frequency range of 0.01 Hz to several tens of kHz) to determine the battery's condition from the frequency characteristics of the AC impedance.

One known method for superimposing an AC current of a first reference frequency onto a battery is to pass high-frequency pulses of current through the battery that are significantly higher than the first reference frequency, thereby achieving highly efficient AC superposition. In the impedance measurement device disclosed in Patent Document 2, a switching circuit that forms a loop circuit with the battery generates a high-frequency intermittent current. The switching circuit includes a first switch and a second switch inserted in series on the loop circuit, an inductor and a power storage device connected in series in parallel with the second switch, and a drive controller that controls and drives the first and second switches. The drive controller alternately turns the first and second switches on and off at a predetermined on-duty, allowing a pulsed current to flow from the battery to charge the power storage device. By repeating this switching operation period and a period when the switching operation is stopped, the flowing current and battery voltage are measured, and the AC impedance corresponding to this repetition frequency, i.e., the first reference frequency, is calculated. Furthermore, by passing a pulsed current regenerated from the power storage device to the battery, the voltage of the power storage device can be controlled within a predetermined range and changes in battery capacity can be suppressed.

International Publication No. 2020/261799 International Publication No. 2023/127478

However, the method disclosed in Patent Document 2 requires components such as an inductor and a power storage device (capacitor), which results in the impedance measurement device becoming larger.

This disclosure therefore provides a drive measurement circuit that enables the miniaturization of impedance measurement devices.

A driving and measuring circuit according to one aspect of the present disclosure is a driving and measuring circuit for controlling an impedance measuring device that measures the AC impedance of a first battery and a second battery connected in series, the impedance measuring device comprising: a storage element that stores or releases electrical energy; a switching circuit consisting of a plurality of switching elements that intermittently transfers electrical energy between the first battery and the second battery via the storage element; and a current detection means that detects the current of the first battery and the current of the second battery, and the driving and measuring circuit controls the impedance measuring device to measure the AC impedance of a first battery and a second battery based on the detection result of the current detection means. The device comprises a current measuring unit that measures the current of the first battery and the current of the second battery, a voltage measuring unit that measures the voltage of the first battery and the voltage of the second battery, an AC detection unit that receives a measurement instruction signal including measurement frequency information from a host system having a function of calculating AC impedance, and measures AC voltage and AC current corresponding to the measurement frequency based on the measurement results of the voltage measuring unit and the current measuring unit, and outputs the results to the host system, and a drive control unit that drives the multiple switching elements to periodically change the state of electrical energy transfer through the storage elements according to the measurement frequency.

An impedance measuring device according to one embodiment of the present disclosure is an impedance measuring device that measures the AC impedance of a first battery and a second battery connected in series, and includes: a storage element that stores or releases electrical energy; a switching circuit consisting of a plurality of switching elements that intermittently transfers electrical energy between the first battery and the second battery via the storage element; a current detection means that detects the current of the first battery and the current of the second battery; and a drive measurement circuit. The drive measurement circuit includes a current measurement unit that measures the current of the first battery and the current of the second battery based on the detection results of the current detection means; a voltage measurement unit that measures the voltage of the first battery and the voltage of the second battery; an AC detection unit that receives a measurement instruction signal including information about a measurement frequency from a higher-level system having the function of calculating AC impedance, and measures AC voltage and AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement unit and the current measurement unit and outputs them to the higher-level system; and a drive control unit that drives the plurality of switching elements to periodically change the state of transfer of electrical energy via the storage element in accordance with the measurement frequency.

An impedance measurement system according to one embodiment of the present disclosure comprises an impedance measurement device that measures the AC impedance of a first battery and a second battery connected in series, a drive measurement circuit for controlling the impedance measurement device, and a host system having the function of calculating the AC impedance, wherein the impedance measurement device comprises a storage element that stores or releases electrical energy, a switching circuit consisting of a plurality of switching elements that intermittently transfers electrical energy between the first battery and the second battery via the storage elements, and a current detection means that detects the current of the first battery and the current of the second battery. The drive measurement circuit comprises a current measurement unit that measures the current of the first battery and the current of the second battery based on the detection result of the current detection means, a voltage measurement unit that measures the voltage of the first battery and the voltage of the second battery, an AC detection unit that receives a measurement instruction signal including measurement frequency information from the higher-level system and measures AC voltage and AC current corresponding to the measurement frequency based on the measurement result of the voltage measurement unit and the measurement result of the current measurement unit, and outputs the measured values to the higher-level system, and a drive control unit that drives the multiple switching elements to periodically change the state of electrical energy transfer through the storage elements according to the measurement frequency.

A driving measurement method according to one aspect of the present disclosure is a driving measurement method for controlling an impedance measurement device that measures the AC impedance of a first battery and a second battery connected in series, the impedance measurement device comprising: a storage element that stores or releases electrical energy; a switching circuit consisting of a plurality of switching elements that intermittently transfers electrical energy between the first battery and the second battery via the storage element; and a current detection means that detects the current of the first battery and the current of the second battery, and the driving measurement method includes receiving a measurement frequency signal from a host system having a function of calculating AC impedance. The method includes a power receiving step of receiving a measurement instruction signal including wave number information, a drive step of driving the multiple switching elements so as to periodically change the state of electrical energy transfer through the storage elements in accordance with the measurement frequency, a current measurement step of measuring the current of the first battery and the current of the second battery based on the detection results of the current detection means, a voltage measurement step of measuring the voltage of the first battery and the voltage of the second battery, and an AC detection step of measuring AC voltage and AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement step and the measurement results of the current measurement step, and outputting the results to the host system.

The drive measurement circuit according to one aspect of the present disclosure makes it possible to miniaturize impedance measurement devices.

FIG. 1 is a schematic diagram showing an example of an impedance measurement system according to the first embodiment. FIG. 2 is a circuit diagram showing an example of the voltage measuring unit, the current measuring unit, and the AC detecting unit of the impedance measuring device according to the first embodiment. FIG. 3 is a circuit configuration diagram showing an example of the drive control unit of the impedance measuring device according to the first embodiment. FIG. 4 is a timing chart showing an example of the operation of the impedance measuring device according to the first embodiment. FIG. 5 is a schematic diagram showing an example of an impedance measuring device according to the second embodiment. FIG. 6 is a configuration diagram showing an example of a current measuring unit of the impedance measuring device according to the second embodiment. FIG. 7 is a schematic diagram showing an example of an impedance measuring device according to the third embodiment. FIG. 8 is a circuit configuration diagram showing an example of a drive control unit of an impedance measuring device according to the third embodiment. FIG. 9 is a timing chart showing an example of the operation of the impedance measuring device according to the third embodiment. FIG. 10 is a circuit configuration diagram showing an example of a drive control unit of the impedance measuring device according to the fourth embodiment. FIG. 11 is a timing chart showing an example of the operation of the impedance measuring device according to the fourth embodiment. FIG. 12 is a flowchart showing an example of a driving and measuring method according to another embodiment.

The following describes the embodiments in detail with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not recited in independent claims will be described as optional components.

Note that each figure is a schematic diagram and is not necessarily an exact illustration. Furthermore, in each figure, substantially identical components are designated by the same reference numerals, and duplicate explanations may be omitted or simplified.

(Embodiment 1)
Fig. 1 is a schematic diagram showing an example of an impedance measurement system 100 according to embodiment 1. In Fig. 1, batteries B1 and B2 are also shown in addition to the impedance measurement system 100.

The impedance measurement system 100 comprises an impedance measurement device 1 and a host system 200. The impedance measurement device 1 is a device that measures the AC impedance of batteries B1 and B2 connected in series. Battery B1 is an example of a first battery, and battery B2 is an example of a second battery. For example, batteries B1 and B2 are rechargeable secondary batteries such as lithium-ion batteries, and battery B1 is located at a higher potential than battery B2. The host system 200 is a system that has the function of calculating the AC impedance.

The impedance measuring device 1 comprises a storage element that stores or releases electrical energy, a switching circuit consisting of multiple switching elements that intermittently transfers electrical energy between batteries B1 and B2 via the storage elements, current detection means that detects the current of batteries B1 and B2, and a drive measurement circuit 2. Note that the impedance measuring device 1 does not necessarily have to comprise the drive measurement circuit 2, and the impedance measuring device 1 and the drive measurement circuit 2 may be provided separately. Similarly, in the second to fourth embodiments described below, the impedance measuring device and the drive measurement circuit may be provided separately.

In embodiment 1, the storage element is inductor 14. In embodiment 1, the switching circuit has a first switching element 11 that forms a first loop together with battery B1 and inductor 14, and a second switching element 12 that forms a second loop together with battery B2 and inductor 14. For example, the switching circuit has current interruption means 13 connected in series with inductor 14. For example, the current detection means has detection resistor 15 connected between battery B1 and first switching element 11, and detection resistor 16 connected between battery B2 and second switching element 12. Detection resistor 15 is an example of a first detection resistor, and detection resistor 16 is an example of a second detection resistor. The current of battery B1 can be detected by detecting the current flowing through detection resistor 15, and the current of battery B2 can be detected by detecting the current flowing through detection resistor 16.

The first switching element 11 and the second switching element 12 are, for example, N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The drain of the first switching element 11 is connected to the positive electrode of battery B1, the source of the first switching element 11 is connected to the drain of the second switching element 12, and the source of the second switching element 12 is connected to the negative electrode of battery B2. A series circuit of the current interruption means 13 and inductor 14 is connected between the connection point between batteries B1 and B2 and the connection point between the first switching element 11 and the second switching element 12. For example, a detection resistor 15 is connected between the positive electrode of battery B1 and the drain of the first switching element 11 to detect the charge/discharge current I1 of battery B1. For example, the detection resistor 16 is connected between the negative electrode of battery B2 and the source of the second switching element 12 to detect the charge/discharge current I2 of battery B2.

The first switching element 11 and the second switching element 12 are switching elements that become conductive when a voltage is applied to their control terminals (gates), and conduct current in the opposite direction (the opposite direction to the arrows of currents I1 and I2 shown in Figure 1) using, for example, body diodes, and are represented as field-effect transistors as an example. Furthermore, the current interruption means 13 conducts and interrupts current in both directions, so is usually configured with two field-effect transistors connected face to face, but to avoid complicating the diagram, it is represented by the circuit symbol for a switch.

The drive measurement circuit 2 is a circuit for controlling the impedance measurement device 1 (specifically, the switching circuit provided in the impedance measurement device 1), and includes a voltage measurement unit 20, a current measurement unit 21, an AC detection unit 22, and a drive control unit 23.

The voltage measurement unit 20 measures the voltage of battery B1 and the voltage of battery B2. The current measurement unit 21 measures the current of battery B1 and the current of battery B2 based on the detection results of the current detection means. Specifically, the current measurement unit 21 measures the current I1 flowing from the detection voltage Vc1 of the detection resistor 15 to battery B1, and measures the current I2 flowing from the detection voltage Vc2 of the detection resistor 16 to battery B2.

The AC detection unit 22 receives a measurement instruction signal containing measurement frequency information from the host system 200, and transmits an enable signal EN and a control signal Vs to the drive control unit 23 in accordance with the measurement instruction signal, and also transmits information necessary for calculating AC impedance (voltage information from the voltage measurement unit 20 and current information from the current measurement unit 21) to the host system 200. Details of the AC detection unit 22 will be described later.

The drive control unit 23 drives the first switching element 11 and the second switching element 12 based on the enable signal EN and the control signal Vs from the AC detection unit 22. Details of the drive control unit 23 will be described later.

The upper system 200 may be any system that has a computing function similar to that of a CPU, such as an MCU (Micro Control Unit) or ECU (Electronic Control Unit).

Next, we will explain the details of the configuration of the AC detection unit 22.

FIG. 2 is a circuit diagram showing an example of the voltage measurement unit 20, current measurement unit 21, and AC detection unit 22 of the impedance measurement device 1 according to embodiment 1. FIG. 2 mainly shows the internal configuration of the voltage measurement unit 20, current measurement unit 21, and AC detection unit 22. In FIG. 2, battery B1 and battery B2 each consist of a series configuration of multiple battery cells, and the voltage measurement unit 20 is configured to measure the voltage of each individual battery cell. Both the voltage measurement unit 20 and the current measurement unit 21 have analog-to-digital converters (hereinafter abbreviated as ADCs) that convert the detected voltages into digital signals, and the voltage information from the voltage measurement unit 20 and the current information from the current measurement unit 21 are transmitted to the AC detection unit 22 as digital values. Each ADC measures the voltage and current of batteries B1 and B2 at the sampling frequency of a clock signal CK, which will be described later.

As shown in FIG. 2, for example, the AC detection unit 22 has a signal generation unit 220, a conversion unit 221, an integration unit 222, a holding unit 223, and a communication unit 224.

The signal generating unit 220 outputs a first reference frequency signal of frequency f in accordance with a measurement command from the upper system 200, a second reference frequency signal having a phase orthogonal to that of the first reference frequency signal, and a clock signal CK to each ADC of the voltage measuring unit 20 and the current measuring unit 21. The first reference frequency signal is a sine wave (sin), and the second reference frequency signal is a cosine wave (cos). The clock signal CK is a signal with a higher frequency than the first reference frequency signal and is synchronized with the first reference frequency signal.

The conversion unit 221 has a multiplier pair corresponding to each ADC, and converts each digital value from each ADC into a real component and an imaginary component of a complex voltage and a complex current by multiplying each digital value from each ADC by a first reference frequency signal sin and a second reference frequency signal cos using each multiplier pair. The result of multiplication by the first reference frequency signal sin indicates the real component when the sampled voltage is expressed as a complex voltage. The result of multiplication by the second reference frequency signal cos indicates the imaginary component when the sampled voltage is expressed as a complex voltage.

The integrator unit 222 has an equal number of averaging circuit pairs corresponding to the multiplier pairs of the converter unit 221, and averages the real and imaginary components of the complex voltage and complex current that have been repeatedly measured and converted by the converter unit 221. This averaging reduces measurement errors in the complex voltage and complex current, and oversampling improves resolution (measurement accuracy). As a result, even with an ADC with a small number of bits (for example, around 16 bits), it is possible to obtain AC impedance measurement results with 20 to 24 bits of accuracy.

The holding unit 223 holds the real and imaginary components of the complex voltage and complex current after averaging. Each register pair for holding complex voltages consists of a register Re that holds the real component of the complex voltage and complex current of the corresponding battery cell, and a register Im that holds the imaginary component.

The communication unit 224 is a communication circuit for communicating with the host system 200, and is used to transmit data stored in the storage unit 223 to the host system 200, and to receive measurement instruction signals (operation instructions to the drive control unit 23 and information on the frequency f of the first reference frequency signal) from the host system 200. The communication performed by the communication unit 224 may be wireless or wired, and there are no particular limitations on the communication standard.

Next, the configuration of the drive control unit 23 will be described in detail.

FIG. 3 is a circuit diagram showing an example of the drive control unit 23 of the impedance measuring device 1 according to embodiment 1. FIG. 3 shows the internal configuration of the drive control unit 23.

As shown in FIG. 3, oscillator 230 outputs a reference clock CK0 that sets the switching period, and a clock CK1 that is delayed from reference clock CK0 by the maximum on-period of first switching element 11 and second switching element 12. In embodiment 1, an example is shown in which these clock signals are generated by oscillator 230 of drive control unit 23, but these clock signals may be received from a higher-level system 200 or the like, or the clock signal CK of AC detection unit 22 may be used, or these clock signals may be signals synchronized with clock signal CK.

Reference voltage source 231 generates threshold voltage Vr1, reference voltage source 232 generates threshold voltage Vr2, comparator 233 compares detection voltage Vc1 with threshold voltage Vr1, and comparator 234 compares detection voltage Vc2 with reference voltage Vr2. This disclosure shows an example in which these threshold voltages are generated internally in drive control unit 23, but these threshold voltages may also be supplied from host system 200 or the like, or, as will be described later, these threshold voltages may be made variable by instructions from host system 200.

Clock CK1, the output of comparator 233, and the output of comparator 234 are input to OR circuit 235. Reference clock CK0 sets SR latch 236, and the output of OR circuit 235 resets SR latch 236. Outputs Q and NQ of SR latch 236 are input to switch circuit 237 and switch circuit 238. Control signal Vs from AC detection unit 22 is a signal that switches between high and low depending on the phase of the first reference frequency signal. Since the first reference frequency signal is a signal of the measurement frequency (frequency f) in accordance with the measurement command from upper system 200, control signal Vs is a signal of frequency f. When control signal Vs is at H level, switch circuit 237 selects and outputs output Q of SR latch 236, and switch circuit 238 selects and outputs output NQ. When control signal Vs is at L level, switch circuit 237 selects and outputs output NQ of SR latch 236, and switch circuit 238 selects and outputs output Q. The output of switch circuit 237 becomes a signal that drives the first switching element 11, and the output of switch circuit 238 becomes a signal that drives the second switching element 12.

Since the abnormality detection circuit 239 is not the essence of the present application, detailed explanation and illustration will be omitted, but the abnormality detection circuit 239 outputs an H-level abnormality signal Fail when the current or voltage value of each battery detected by the AC detection unit 22, or the temperature of each battery detected by a temperature sensor (not shown), indicates an abnormal value. The abnormality signal Fail is logically inverted by an inverter 240 and input to an AND circuit 241 together with an enable signal EN. The output of the AND circuit 241 is a drive signal V13 for the current interruption means 13. When the drive signal V13 is H-level, the current interruption means 13 is conductive, and when it is L-level, it is interrupted. The output of the switch circuit 237 and the drive signal V13 are input to an AND circuit 242, which outputs a drive signal Vg1. The output of the switch circuit 238 and the drive signal V13 are input to an AND circuit 243, which outputs a drive signal Vg2. In other words, if there are no abnormalities and a measurement command is received from the host system 200, the drive signal V13 turns on the current interruption means 13, electrically connecting the inductor 14 to the first switching element 11 and the second switching element 12, and the first switching element 11 and the second switching element 12 are alternately driven on and off.

In order to prevent the first switching element 11 and the second switching element 12 from being turned on at the same time, a dead time is provided during which the drive signals Vg1 and Vg2 are both turned off at the same time. Although not shown, it is assumed here that a delay time equivalent to the dead time is provided at the rising edge of each drive signal.

Next, the operation of the drive control unit 23 will be described in detail.

FIG. 4 is a timing chart showing an example of the operation of the impedance measuring device 1 according to embodiment 1. FIG. 4 is a timing chart showing the operation of the main parts of the drive control unit 23, and shows the reference clock CK0, clock CK1, control signal Vs, drive signal Vg1, detection voltage Vc1, drive signal Vg2, and detection voltage Vc2. Although not shown, the enable signal EN is at H level, and the abnormality signal Fail is at L level. The detection voltage Vc1 corresponds to the current I1 flowing through battery B1 and the first switching element 11, and the detection voltage Vc2 corresponds to the current I2 flowing through battery B2 and the second switching element 12. For example, the threshold voltages Vr1 and Vr2 may be the same voltage; in FIG. 4, the threshold voltages Vr1 and Vr2 are shown as threshold voltage Vr. Below, using FIG. 4, we will explain how the drive control unit 23 of the impedance measuring device 1 according to embodiment 1 efficiently passes high-frequency current pulses through batteries B1 and B2.

First, as shown on the left side of Figure 4, we will explain the operation of the drive control unit 23 from time t0 to t2 when the control signal Vs is at H level. Because the control signal Vs is at H level from time t0 to t2, the output Q of the SR latch 236 is output as the drive signal Vg1 for the first switching element 11, and the output NQ of the SR latch 236 is output as the drive signal Vg2 for the second switching element 12.

At time t0, when the reference clock CK0 rises, the SR latch 236 is set, output Q, i.e., drive signal Vg1, rises, and output NQ, i.e., drive signal Vg2, falls. Drive signal Vg1 turns on the first switching element 11 and conducts, causing current I1 to flow through the first loop from the positive electrode of battery B1 to the negative electrode of battery B1 via the first switching element 11, inductor 14, and current interruption means 13. Meanwhile, drive signal Vg2 goes low, turning off the second switching element 12, preventing current I2 from flowing and causing the detection voltage Vc2 to become zero. Current I1 increases at a rate determined by the voltage of battery B1 and the inductance of inductor 14, and the detection voltage Vc1 also increases in proportion to current I1.

At time t1, when the detection voltage Vc1 reaches the threshold voltage Vr1, the output of the comparator 233 inverts to an H level and resets the SR latch 236 via the OR circuit 235. The reset of the SR latch 236 causes the output Q, i.e., the drive signal Vg1, to fall, and the output NQ, i.e., the drive signal Vg2, to rise. The first switching element 11 turns off, and the voltage of the inductor 14 inverts. The body diode of the second switching element 12 conducts, and after a dead time, the second switching element 12 turns on. Note that the dead time is a very short period and is not shown in the figure; the conduction of the body diode of the second switching element 12 and the turning on of the second switching element 12 are depicted as occurring simultaneously at time t1. The current in the inductor 14 is maintained, and current I2 flows through the second loop from the negative pole of battery B2 via the second switching element 12, inductor 14, and current interruption means 13 to the positive pole of battery B2. This is a negative current, opposite in direction to current I2 in the diagram, and increases in the positive direction at a slope determined by the voltage of battery B2 and the inductance of inductor 14, with the initial value being a current value whose absolute value corresponds to threshold voltage Vr1.

When time t2 is reached, the reference clock CK0 rises and the operation from time t0 is repeated. This repetition causes a pulse current I1 to flow in the direction of discharging battery B1, with a peak current value corresponding to threshold voltage Vr1, and a pulse current I2 to flow in the direction of charging battery B2, with a peak current value corresponding to threshold voltage Vr1.

Next, at time t3, when control signal Vs goes low, switch circuit 237 switches to select and output NQ from SR latch 236, and switch circuit 238 switches to select and output Q from SR latch 236. As a result, the timing at which drive signals Vg1 and Vg2 rise also changes. Specifically, drive signal Vg2 goes high on the rising edge of reference clock CK0, and goes low when detection voltage Vc2 reaches threshold voltage Vr2 or clock CK1 rises. From time t3, current I2 continues to flow, and current I2 increases.

At time t4, when the on state of the second switching element 12 reaches its maximum on period, clock CK1 rises, the SR latch 236 is reset via the OR circuit 235, drive signal Vg2 falls, and the second switching element 12 turns off. If the increasing current I2 has now reached the positive direction, the voltage of inductor 14 reverses. The body diode of the first switching element 11 becomes conductive, and after the dead time, the first switching element 11 turns on.

At time t5, the reference clock CK0 rises, the SR latch 236 is set, output Q (i.e., drive signal Vg2) rises, and output NQ (i.e., drive signal Vg1) falls. Drive signal Vg2 turns on the second switching element 12, causing current I2 to flow through the second loop from the positive electrode of battery B2 to the negative electrode of battery B2 via the current interruption means 13, inductor 14, and second switching element 12. Meanwhile, drive signal Vg1 goes low, turning off the first switching element 11. Current I1 does not flow, and detection voltage Vc1 also becomes zero. Current I2 increases at a rate determined by the voltage of battery B2 and the inductance of inductor 14, and detection voltage Vc2 also increases in proportion to current I2. Thereafter, the operation from time t3, when the second switching element 12 performs switching operation for its maximum on-period, is repeated. This repetition causes the peak value of current I2 to increase.

At time t6, when the detection voltage Vc2 of current I2 reaches the threshold voltage Vr2, the output of comparator 234 inverts to an H level and resets SR latch 236 via OR circuit 235. Resetting SR latch 236 causes output Q, i.e., drive signal Vg2, to fall, and output NQ, i.e., drive signal Vg1, to rise. The second switching element 12 turns off, and the voltage of inductor 14 inverts. The body diode of first switching element 11 conducts, and after a dead time, the first switching element 11 turns on. The current in inductor 14 is maintained, and current I1 flows through the first loop from the negative pole of battery B1 via current interruption means 13, inductor 14, and first switching element 11 to the positive pole of battery B1. This is a negative current, opposite in direction to current I1 in the diagram, and increases in the positive direction at a slope determined by the voltage of battery B1 and the inductance of inductor 14, with the initial value being a current value whose absolute value corresponds to threshold voltage Vr2.

At time t7, the reference clock CK0 rises and the operation from time t5 is repeated. This repetition causes a pulse current I2 to flow in the direction of discharging battery B2, with a peak current value corresponding to threshold voltage Vr2, and a pulse current I1 to flow in the direction of charging battery B1, with a peak current value corresponding to threshold voltage Vr2.

Next, at time t8, when control signal Vs goes high, switch circuit 237 switches to select and output output Q of SR latch 236, and switch circuit 238 switches to select and output output NQ of SR latch 236. As a result, the timing at which drive signals Vg1 and Vg2 rise also changes. Specifically, drive signal Vg1 goes high on the rising edge of reference clock CK0, and goes low when detection voltage Vc2 reaches threshold voltage Vr2 or clock CK1 rises. From time t8, current I1 continues to flow, and current I1 increases.

After this, current I1 increases and current I2 decreases due to the switching operation of the first switching element 11 during its maximum on-period, and eventually the peak value of current I1 reaches a current value corresponding to threshold voltage Vr1, and the operation from time t0 onwards is carried out again.

As described above, in accordance with the control signal Vs, batteries B1 and B2 are repeatedly charged and discharged with low loss using a pulse current of a predetermined peak value. Current I1, which is the charging/discharging current, is converted to detection voltage Vc1 by detection resistor 15, and current I2 is converted to detection voltage Vc2 by detection resistor 16 and input to current measurement unit 21. During AC impedance measurement, impedance measurement device 1 regenerates energy drawn from battery B1 to battery B2 during the H level period of control signal Vs, and regenerates energy drawn from battery B2 to battery B1 during the L level period of control signal Vs. Therefore, if the H level period and L level period of control signal Vs are equal and threshold voltage Vr1 and threshold voltage Vr2 are equal, the charging and discharging charges of batteries B1 and B2 will also be equal, thereby suppressing fluctuations in battery voltage and changes in charge capacity SOC (state of charge).

Conversely, by differentiating threshold voltage Vr1 from threshold voltage Vr2, or by changing the ratio of the high and low periods of control signal Vs, energy can be transferred from battery B1 to battery B2, or from battery B2 to battery B1. For example, when transferring energy from battery B1 to battery B2, it is advisable to set threshold voltage Vr1 higher than threshold voltage Vr2, or to make the H level period of control signal Vs longer than the L level period. Although it is different from the gist of this disclosure, because the voltage of each battery is also monitored, this energy transfer can also be applied to maintaining battery voltage balance.

As explained above, the AC detection unit 22 receives a measurement instruction signal containing information about the measurement frequency from the host system 200, which has the function of calculating AC impedance, and measures the AC voltage and AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement unit 20 and the current measurement unit 21, and outputs them to the host system 200. Furthermore, the drive control unit 23 drives multiple switching elements (here, the first switching element 11 and the second switching element 12) so as to periodically change the state of electrical energy transfer via the inductor 14 according to the measurement frequency.

As a result, the state of electrical energy transfer between batteries B1 and B2 is changed periodically in accordance with the measurement frequency, making it possible to measure the AC voltage and AC current in accordance with the measurement frequency, and thus the AC impedance of batteries B1 and B2. In this case, the state of electrical energy transfer can be changed via a single inductor 14 provided in the impedance measuring device 1, eliminating the need for both an inductor and a power storage device (capacitor) as in the method disclosed in Patent Document 2. This allows the impedance measuring device 1 to be made smaller. In other words, the AC impedance of batteries B1 and B2 connected in series can be appropriately obtained using a small number of components.

Furthermore, in the method disclosed in Patent Document 2, the power storage device may be a battery, but there is a restriction that it must have a lower potential than the battery being measured. On the other hand, the drive measurement circuit 2 can measure AC impedance without being affected by the magnitude relationship between the voltages of battery B1 and battery B2, so usage restrictions can be relaxed.

Furthermore, the method disclosed in Patent Document 2 has the problem that, in order to prevent a drop in the battery's SOC (State of Charge), time is required for the energy charged in the storage device during measurement to be regenerated back into the battery after the measurement. On the other hand, the drive measurement circuit 2 generates an intermittent current at all times during measurement without any pauses, thereby shortening the measurement time.

As shown in FIG. 2, batteries B1 and B2 may each be composed of two or more battery cells, and voltage measurement unit 20 may measure the voltages of two or more battery cells simultaneously. This allows the voltages of battery B1 and battery B2 to be measured in a short period of time.

Also, as shown in FIG. 4, the drive control unit 23 may alternately turn on the first switching element 11 and the second switching element 12 at a frequency higher than the measurement frequency. This shortens the time that current flows through the inductor 14 at one time. In other words, since a large current is less likely to flow through the inductor 14, the inductor 14 can be made smaller, which in turn makes it possible to make the impedance measuring device 1 more compact.

The drive control unit 23 may also control the on-time of the first switching element 11 and the on-time of the second switching element 12 so as to repeat, at a period corresponding to the measurement frequency, a first energy transfer state (from time t0 to time t4 in FIG. 4) in which a discharge current is caused to flow from battery B1 when the first switching element 11 is on and a charge current is caused to flow to battery B2 when the second switching element 12 is on, and a second energy transfer state (from time t4 to time t8 in FIG. 4) in which a discharge current is caused to flow from battery B2 when the second switching element 12 is on and a charge current is caused to flow to battery B1 when the first switching element 11 is on.

As a result, by lengthening the on-time of the second switching element 12, as shown from time t3 to time t4 in Figure 4, it is possible to start a discharge current flow from battery B2, thereby switching from the first energy transfer state to the second energy transfer state. Furthermore, by lengthening the on-time of the first switching element 11, as shown from time t8 onwards in Figure 4, it is possible to start a discharge current flow from battery B1, thereby switching from the second energy transfer state to the first energy transfer state.

Furthermore, the drive control unit 23 may limit the peak value of the discharge current from battery B1 to a predetermined value (a value corresponding to threshold voltage Vr1) in the first energy transfer state, and may limit the peak value of the discharge current from battery B2 to a predetermined value (a value corresponding to threshold voltage Vr2) in the second energy transfer state. This makes it possible to limit the discharge current from battery B1 and the discharge current from battery B2, thereby suppressing switching losses that occur during switching.

The switching circuit may also have a current interruption means 13 connected in series with the inductor 14, and the drive control unit 23 may interrupt the current flowing through the current interruption means 13 when the detection results of the detection resistors 15 and 16 exceed a predetermined amount. This allows the current to be interrupted when an overcurrent flows.

(Embodiment 2)
Next, a description will be given of a second embodiment. In the second embodiment, the current detection means includes one of detection resistors 15 connected between battery B1 and first switching element 11 and detection resistor 16 connected between battery B2 and second switching element 12, and detection resistor 17 connected in series with inductor 14. An example in which the current detection means includes detection resistors 16 and 17 will be described below.

FIG. 5 is a schematic diagram showing an example of an impedance measuring device 1A according to embodiment 2. In addition to impedance measuring device 1A, FIG. 5 also shows batteries B1 and B2. In FIG. 5, the same components as those shown in FIG. 1 are given the same numbers, and their descriptions are omitted or simplified. The difference from the impedance measuring device 1 shown in FIG. 1 is the configuration for detecting the current of battery B1. Instead of detection resistor 15 in FIG. 1, detection resistor 17 is inserted in series with current interruption means 13 and inductor 14, and current I3 flowing through detection resistor 17 is detected. The voltage across detection resistor 17 is set as detection voltage Vc3, and detection voltage Vc3 is input to current measurement unit 21A for processing.

FIG. 6 is a configuration diagram showing an example of a current measurement unit 21A of an impedance measurement device 1A according to embodiment 2. In addition to the current measurement unit 21A, FIG. 6 also shows the peripheral circuitry of the current measurement unit 21A. Compared to the current measurement unit 21 in FIG. 2, the current measurement unit 21A has an additional adder 210, and outputs the sum of the outputs of the ADC that digitally converts the detection voltage Vc2 and the ADC that digitally converts the detection voltage Vc3 as detection data for the current I1. The current I3 flowing through the detection resistor 17 is the difference between the currents I1 and I2 (i.e., I3 = I1 - I2). Therefore, to detect the current I1 in the same way as in embodiment 1 of FIG. 1, it is sufficient to calculate the sum of the currents I2 and I3 (i.e., I1 = I2 + I3).

As described above, in embodiment 2, the position of the detection resistor has been changed from the configuration of embodiment 1, and the signal processing has also been changed accordingly. Compared to embodiment 1, where detection resistor 15 is connected to a high potential such as the positive electrode of battery B1, because it is connected to the midpoint of the battery, it is easier to configure the level shift circuit and has the effect of improving detection accuracy. Although not shown, detection resistor 15 may be provided instead of detection resistor 16. In other words, detection resistor 15 may be connected to a high potential such as the positive electrode of battery B1.

Furthermore, by implementing all or part of the drive and measurement circuit 2 in embodiment 1, or all or part of the drive and measurement circuit 2A in embodiment 2 as an integrated circuit, the device can be made even smaller and more versatile.

(Embodiment 3)
In the first and second embodiments, an example has been described in which the storage element that stores or releases electrical energy is the inductor 14, but in the third embodiment, an example will be described in which the storage element is a capacitor.

FIG. 7 is a schematic diagram showing an example of an impedance measuring device 3 according to embodiment 3. In addition to the impedance measuring device 3, FIG. 7 also shows batteries B1 and B2. The impedance measuring device 3 measures the AC impedance of batteries B1 and B2, which are connected in series.

The impedance measuring device 3 comprises a storage element that stores or releases electrical energy, a switching circuit consisting of multiple switching elements that intermittently transfers electrical energy between batteries B1 and B2 via the storage elements, current detection means that detects the currents of batteries B1 and B2, and drive measurement circuits 4 and 5.

In embodiment 3, the storage element is a capacitor 30. In embodiment 3, the switching circuit has a third switching element 31 connected between the positive electrode of battery B1 and the positive electrode of capacitor 30, and a fourth switching element 32 connected between the negative electrode of battery B1 and the positive electrode of capacitor 30. The switching circuit also has a fifth switching element 34 connected between the negative electrode of battery B2 and the negative electrode of capacitor 30, and a sixth switching element 35 connected between the positive electrode of battery B2 and the negative electrode of capacitor 30.

For example, the current detection means has a detection resistor 33 connected between battery B1 and the third switching element 31, and a detection resistor 36 connected between battery B2 and the fifth switching element 34. Detection resistor 33 is an example of a first detection resistor, and detection resistor 36 is an example of a second detection resistor. The current of battery B1 can be detected by detecting the current flowing through detection resistor 33, and the current of battery B2 can be detected by detecting the current flowing through detection resistor 36. Current I1 flowing through battery B1 is converted to a detection voltage Vc1 by detection resistor 33, and current I2 flowing through battery B2 is converted to a detection voltage Vc2 by detection resistor 36.

The third switching element 31, the fourth switching element 32, the fifth switching element 34, and the sixth switching element 35 are, for example, N-channel MOSFETs. The drain of the third switching element 31 is connected to the positive electrode of battery B1, and the source of the third switching element 31 is connected to the positive electrode of capacitor 30. The drain of the fourth switching element 32 is connected to the positive electrode of capacitor 30, and the source of the fourth switching element 32 is connected to the negative electrode of battery B1. The drain of the fifth switching element 34 is connected to the negative electrode of capacitor 30, and the source of the fifth switching element 34 is connected to the negative electrode of battery B2. The drain of the sixth switching element 35 is connected to the positive electrode of battery B2, and the source of the sixth switching element 35 is connected to the negative electrode of capacitor 30.

In response to a measurement instruction signal from the host system 200, the drive measurement circuit 4 outputs a drive signal Vg3 for the third switching element 31 and a drive signal Vg4 for the fourth switching element 32, receives the voltage and current detection signal Vc1 of battery B1, and transmits the measurement results to the host system 200. Similarly, in response to a measurement instruction signal from the host system 200, the drive measurement circuit 5 outputs a drive signal Vg5 for the fifth switching element 34 and a drive signal Vg6 for the sixth switching element 35, receives the voltage and current detection signal Vc2 of battery B2, and transmits the measurement results to the host system 200.

The third switching element 31, fourth switching element 32, fifth switching element 34, and sixth switching element 35 are switching elements that become conductive when a voltage is applied to their control terminals (gates), and conduct current in the reverse direction (the direction opposite to the arrows of currents I1 and I2 shown in Figure 7) using, for example, a body diode, and are represented as field-effect transistors as an example.

The drive measurement circuit 4 includes a voltage measurement unit 40, a current measurement unit 41, an AC detection unit 42, and a drive control unit 43. The drive measurement circuit 5 includes a voltage measurement unit 50, a current measurement unit 51, an AC detection unit 52, and a drive control unit 53.

The voltage measurement unit 40 measures the voltage of battery B1. The current measurement unit 41 measures the current of battery B1 based on the detection result of the current detection means. Specifically, the current measurement unit 41 measures the current I1 flowing from the detection voltage Vc1 of the detection resistor 33 to battery B1.

The AC detection unit 42 receives a measurement instruction signal containing measurement frequency information from the host system 200, and transmits an enable signal EN and a control signal Vs to the drive control unit 43 in accordance with the measurement instruction signal, and also transmits information necessary for calculating the AC impedance of battery B1 (voltage information from the voltage measurement unit 40 and current information from the current measurement unit 41) to the host system 200.

The drive control unit 43 drives the third switching element 31 and the fourth switching element 32 based on the enable signal EN and the control signal Vs from the AC detection unit 42. Details of the drive control unit 43 will be described later.

The voltage measurement unit 50 measures the voltage of battery B2. The current measurement unit 51 measures the current of battery B2 based on the detection result of the current detection means. Specifically, the current measurement unit 51 measures the current I2 flowing from the detection voltage Vc2 of the detection resistor 36 to battery B2.

The AC detection unit 52 receives a measurement instruction signal containing measurement frequency information from the host system 200, and transmits an enable signal EN and a control signal Vs to the drive control unit 53 in accordance with the measurement instruction signal, and also transmits information necessary for calculating the AC impedance of battery B2 (voltage information from the voltage measurement unit 50 and current information from the current measurement unit 51) to the host system 200.

The drive control unit 53 drives the fifth switching element 34 and the sixth switching element 35 based on the enable signal EN and the control signal Vs from the AC detection unit 52. Details of the drive control unit 53 will be described later.

In addition, drive measurement circuit 4 and drive measurement circuit 5 communicate and share clock signals and abnormality signals, which will be described later, via communication unit 6.

The voltage measurement unit 40 of the drive measurement circuit 4 and the voltage measurement unit 50 of the drive measurement circuit 5 have the same configuration as the voltage measurement unit 20 shown in Figure 2, the current measurement unit 41 of the drive measurement circuit 4 and the current measurement unit 51 of the drive measurement circuit 5 have the same configuration as the current measurement unit 21 shown in Figure 2, and the AC detection unit 42 of the drive measurement circuit 4 and the AC detection unit 52 of the drive measurement circuit 5 have the same configuration as the AC detection unit 22 shown in Figure 2, so illustrations and detailed explanations will be omitted.

FIG. 8 is a circuit diagram showing an example of the drive control units 43 and 53 of the impedance measuring device 3 according to embodiment 3. Note that FIG. 8 also shows a portion of the communication unit 6. FIG. 8 shows an internal configuration diagram of the drive control unit 43 of the drive measurement circuit 4, the drive control unit 53 of the drive measurement circuit 5, and a portion of the communication unit 6.

As shown in the drive control unit 43 in Figure 8, the oscillator 430 outputs a reference clock CK0 with a duty ratio of 50% that sets the switching period. In embodiment 3, an example is shown in which the reference clock CK0 is generated by the oscillator 430 of the drive control unit 43, but it may also be received from the higher-level system 200 or the drive measurement circuit 5, or the clock signal CK of the AC detection unit 42 or the AC detection unit 52 may be used, or the reference clock CK0 may be a signal synchronized with the clock signal CK.

The frequency divider circuit 431, which is configured using a D latch, divides the control signal Vs from the host system 200 by two and outputs the divided signal Vs1. While Figure 8 shows a configuration in which this frequency divider circuit 431 is provided in the drive control unit 43 (drive measurement circuit 4), it may also be provided in the host system 200 or the drive measurement circuit 5.

The reference clock CK0, control signal Vs, and frequency-divided signal Vs1 are input to the AND circuit 432. The inverted signal of frequency-divided signal Vs1 obtained via inverter 433 and the output of AND circuit 432 are input to OR circuit 434. The output of OR circuit 434 becomes the signal that drives the third switching element 31, and the inverted signal obtained from the output of OR circuit 434 via inverter 435 becomes the signal that drives the fourth switching element 32.

Since the abnormality detection circuit 436 is not the essence of the present application, detailed explanation and illustration will be omitted, but the abnormality detection circuit 436 outputs an H-level abnormality signal Fail1 when the current value or voltage value of battery B1 detected by the AC detection unit 42, or the temperature of battery B1 detected by a temperature sensor (not shown), indicates an abnormal value. The abnormality signal Fail1 is input to an AND circuit 438 via a NOR circuit 437, along with an enable signal EN. In addition, an abnormality signal Fail2 from the drive measurement circuit 5 (described below) is input to the NOR circuit 437 via a level shift circuit in the communication unit 6.

The output of AND circuit 438 and the output of OR circuit 434 are input to AND circuit 439, which outputs drive signal Vg3. The output of AND circuit 438 and the output of inverter 435 are input to AND circuit 440, which outputs drive signal Vg4. That is, if there is no abnormality (specifically, the abnormality signals Fail1 and Fail2 are both at L level) and a measurement instruction is received from the higher-level system 200, when the control signal Vs is at H level and the frequency-divided signal Vs1 is at H level, the third switching element 31 and the fourth switching element 32 are alternately driven on and off in accordance with the reference clock CK0; when the control signal Vs is at L level and the frequency-divided signal Vs1 is at H level, the third switching element 31 is turned off and the fourth switching element 32 is turned on; and when the frequency-divided signal Vs1 is at L level, the third switching element 31 is turned on and the fourth switching element 32 is turned off.

In addition, to prevent the third switching element 31 and the fourth switching element 32 from being turned on at the same time, a dead time is provided during which the normal drive signal Vg3 and the drive signal Vg4 are both turned off at the same time. Although not shown, it is assumed here that a delay time equivalent to the dead time is provided at the rising edge of each drive signal.

As shown in the drive control unit 53 in Figure 8, the reference clock CK0, the control signal Vs, and the inverted signal of the divided signal Vs1 obtained via the inverter 531 are input to the AND circuit 532. Here, the reference clock CK0 and the divided signal Vs1 are obtained from the drive measurement circuit 4 via the level shift circuit of the communication unit 6, and the control signal Vs is input from the higher-level system 200. The control signal Vs input to the drive measurement circuit 4 and the control signal Vs input to the drive measurement circuit 5 are signals of the same logic, but one of them is level-shifted.

The output of AND circuit 532 and frequency-divided signal Vs1 are input to OR circuit 534. The output of OR circuit 534 becomes the signal that drives the fifth switching element 34, and the inverted signal obtained from the output of OR circuit 534 via inverter 535 becomes the signal that drives the sixth switching element 35.

Since the abnormality detection circuit 536 is not the essence of the present application, a detailed description and illustration will be omitted, but the abnormality detection circuit 536 outputs an H-level abnormality signal Fail2 when the current value or voltage value detected by the AC detection unit 52, or the temperature of battery B2 detected by a temperature sensor (not shown), indicates an abnormal value. The abnormality signal Fail2 is input to an AND circuit 538 via a NOR circuit 537, along with an enable signal EN. In addition, the abnormality signal Fail1 from the drive measurement circuit 4 described above is input to the NOR circuit 537 via the level shift circuit of the communication unit 6.

The output of AND circuit 538 and the output of OR circuit 534 are input to AND circuit 539, which outputs drive signal Vg5. The output of AND circuit 538 and the output of inverter 535 are input to AND circuit 540, which outputs drive signal Vg6. That is, if there is no abnormality (specifically, the abnormality signals Fail1 and Fail2 are both at L level) and a measurement instruction is received from the higher-level system 200, the fifth switching element 34 and the sixth switching element 35 are alternately driven on and off in accordance with the reference clock CK0 when the control signal Vs is at H level and the frequency-divided signal Vs1 is at L level; when the control signal Vs is at L level and the frequency-divided signal Vs1 is at L level, the fifth switching element 34 is turned off and the sixth switching element 35 is turned on; and when the frequency-divided signal Vs1 is at H level, the fifth switching element 34 is turned on and the sixth switching element 35 is turned off.

In addition, to prevent the fifth switching element 34 and the sixth switching element 35 from being turned on at the same time, a dead time is provided during which the normal drive signal Vg5 and the drive signal Vg6 are both turned off at the same time. Although not shown, it is assumed here that a delay time equivalent to the dead time is provided at the rising edge of each drive signal.

FIG. 9 is a timing chart showing an example of the operation of the impedance measuring device 3 according to the third embodiment. FIG. 9 is a timing chart showing the operation of the main components of the drive control unit 43 and the drive control unit 53, and shows the reference clock CK0, the control signal Vs, the frequency-divided signal Vs1, the drive signals Vg3, Vg4, Vg5, and Vg6, the detection voltage Vc1, the detection voltage Vc2, and the positive and negative electrode potentials VP and VN of the capacitor 30. Although not shown, the enable signal EN is at the H level, and the abnormality signals Fail1 and Fail2 are both at the L level. The detection voltage Vc1 corresponds to the current I1 flowing through the battery B1 and the third switching element 31, and the detection voltage Vc2 corresponds to the current I2 flowing through the battery B2 and the fifth switching element 34. Below, we will use FIG. 9 to explain the operation of the impedance measuring device 3 according to the third embodiment, which passes high-frequency current pulses through the batteries B1 and B2.

As shown in Figure 9, during period T0, control signal Vs and frequency-divided signal Vs1 are both at L level, so that for each drive signal, Vg3 is H level, Vg4 is L level, Vg5 is L level, and Vg6 is H level. Because the third switching element 31 is on and the fourth switching element 32 is off, the positive electrode potential VP of capacitor 30 is fixed to the positive electrode potential of battery B1. Because the sixth switching element 35 is on and the fifth switching element 34 is off, the negative electrode potential VN of capacitor 30 is fixed to the negative electrode potential of battery B1 (positive electrode of battery B2). The voltage of capacitor 30 becomes the voltage of battery B1, so no battery current flows, and both detection voltage Vc1 and detection voltage Vc2 are zero.

At time t0, when period T1 begins during which control signal Vs becomes H level, the drive signals Vg3 becomes reference clock CK0, Vg4 becomes the inverted version of reference clock CK0, Vg5 becomes H level, and Vg6 becomes L level. Because the fifth switching element 34 is on and the sixth switching element 35 is off, the negative electrode potential VN of capacitor 30 is fixed to the negative electrode potential of battery B2, and the third switching element 31 and fourth switching element 32 alternately switch on and off. Between times t0 and t1, drive signal Vg3 is H level and drive signal Vg4 is L level, so the third switching element 31 is on and the fourth switching element 32 is off, currents I1 and I2 flow, and capacitor 30 is charged to the sum of the voltages of batteries B1 and B2.

Next, from time t1 to t2, drive signal Vg3 is at L level and drive signal Vg4 is at H level, so third switching element 31 is in the OFF state and fourth switching element 32 is in the ON state, current I2 flows, and capacitor 30 is discharged to the voltage of battery B2. Thus, during period T1, battery B1 repeatedly discharges at the frequency of reference clock CK0, and battery B2 repeatedly charges and discharges at the frequency of reference clock CK0.

At time t3, when period T2 begins in which control signal Vs goes low, the drive signals Vg3 goes low, Vg4 goes high, Vg5 goes high, and Vg6 goes low. Because the fifth switching element 34 is on and the sixth switching element 35 is off, the negative electrode potential VN of capacitor 30 remains fixed to the negative electrode potential of battery B2. Because the third switching element 31 is off and the fourth switching element 32 is on, the positive electrode potential VP of capacitor 30 is fixed to the negative electrode potential of battery B1 (positive electrode of battery B2), and capacitor 30 becomes the voltage of battery B2. No battery current flows, and both detection voltages Vc1 and Vc2 are zero.

At time t4, the control signal Vs goes high and the divided signal Vs1 goes low during period T3. As a result, the drive signals Vg3 goes high, Vg4 goes low, Vg5 is the reference clock CK0, and Vg6 is the inverted version of the reference clock CK0. Because the third switching element 31 is on and the fourth switching element 32 is off, the positive electrode potential VP of capacitor 30 is fixed to the positive electrode potential of battery B1, and the fifth switching element 34 and sixth switching element 35 alternately turn on and off.

Between times t4 and t5, drive signal Vg5 is at H level and drive signal Vg6 is at L level, so fifth switching element 34 is on and sixth switching element 35 is off, current I1 and current I2 flow, and capacitor 30 is charged to the sum of the voltages of batteries B1 and B2.

Next, from time t5 to t6, drive signal Vg5 is at L level and drive signal Vg6 is at H level, so fifth switching element 34 is in the OFF state and sixth switching element 35 is in the ON state, current I2 flows, and capacitor 30 is discharged to the voltage of battery B1. Thus, during period T3, battery B1 repeatedly charges and discharges at the frequency of reference clock CK0, and battery B2 repeatedly discharges at the frequency of reference clock CK0.

At time t7, when the control signal Vs goes low, the drive signals Vg3 goes high, Vg4 goes low, Vg5 goes low, and Vg6 goes high, and the period returns to T0.

As described above, batteries B1 and B2 are repeatedly charged and discharged by pulse current to capacitor 30 in accordance with control signal Vs. Current I1 from battery B1 is converted to detection voltage Vc1 by detection resistor 33 and input to current measurement unit 41 of drive measurement circuit 4, while current I2 from battery B2 is converted to detection voltage Vc2 by detection resistor 36 and input to current measurement unit 51 of drive measurement circuit 5. During AC impedance measurement, impedance measurement device 3 repeatedly charges capacitor 30 from batteries B1 and B2 and discharges capacitor 30 to either battery B1 or B2 while control signal Vs is high. Charging and discharging by switching operation are stopped while control signal Vs is low. While this method does not achieve the same high efficiency as embodiment 1, which uses inductor 14 as a storage element, it reduces losses compared to the conventional method of using a resistive element to pass a superimposed current through the battery, and achieves stable switching operation for the voltage of capacitor 30.

As explained above, the AC detection unit 42 receives a measurement instruction signal containing information about the measurement frequency from the host system 200, which has the function of calculating AC impedance, and measures the AC voltage and AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement units 40 and 50 and the measurement results of the current measurement units 41 and 51, and outputs these to the host system 200. Furthermore, the drive control unit 23 drives multiple switching elements (here, the third switching element 31, the fourth switching element 32, the fifth switching element 34, and the sixth switching element 35) so as to periodically change the state of electrical energy transfer through the capacitor 30 in accordance with the measurement frequency.

As a result, the state of electrical energy transfer between batteries B1 and B2 is changed periodically in accordance with the measurement frequency, making it possible to measure the AC voltage and AC current in accordance with the measurement frequency, and thus the AC impedance of batteries B1 and B2. In this case, the state of electrical energy transfer can be changed via a single capacitor 30 provided in the impedance measuring device 3, eliminating the need for both an inductor and a power storage device (capacitor) as in the method disclosed in Patent Document 2. This allows the impedance measuring device 3 to be made smaller. In other words, the AC impedance of batteries B1 and B2 connected in series can be appropriately obtained using a small number of components.

Furthermore, the drive control units 43 and 53 may alternately turn on the third switching element 31 and the fourth switching element 32 at a frequency higher than the measurement frequency, and alternately turn on the fifth switching element 34 and the sixth switching element 35 at a frequency higher than the measurement frequency, so that the fourth switching element 32 and the sixth switching element 35 are not simultaneously turned on.

This shortens the time it takes to store charge in the capacitor 30 at one time. In other words, a capacitor with a large capacity is no longer necessary, allowing the capacitor 30 to be made smaller, which in turn makes it possible to make the impedance measuring device 3 smaller.

Furthermore, the drive control units 43 and 53 may control the third switching element 31, the fourth switching element 32, the fifth switching element 34, and the sixth switching element 35 to repeat a first energy transfer state, a second energy transfer state, and a stop state at a period corresponding to the measurement frequency. Here, the first energy transfer state is a state in which, as shown in period T3 in FIG. 9 , the third switching element 31 is fixed in the on state, the fourth switching element 32 is fixed in the off state, and the fifth switching element 34 and the sixth switching element 35 are alternately turned on at a frequency higher than the measurement frequency, repeatedly charging battery B1 when the sixth switching element 35 is on and discharging batteries B1 and B2 when the fifth switching element 34 is on. The second energy transfer state, as shown in period T1 in Figure 9, is a state in which the fifth switching element 34 is fixed in the on state, the sixth switching element 35 is fixed in the off state, and the third switching element 31 and the fourth switching element 32 are alternately turned on at a frequency higher than the measurement frequency, repeatedly discharging batteries B1 and B2 when the third switching element 31 is on and charging battery B2 when the fourth switching element 32 is on. The stopped state, as shown in periods T0 and T2 in Figure 9, is a state in which batteries B1 and B2 are not charged or discharged.

In the first energy transfer state, battery B1 repeatedly charges and discharges, so the average current of battery B1 in the first energy transfer state is nearly zero, and the current of battery B1 cannot be measured. On the other hand, in the second energy state, battery B1 repeatedly discharges, so the current of battery B1 can be measured. Also, in the second energy transfer state, battery B2 repeatedly charges and discharges, so the average current of battery B2 in the second energy transfer state is nearly zero, and the current of battery B2 cannot be measured. On the other hand, in the first energy state, battery B2 repeatedly discharges, so the current of battery B2 can be measured. Therefore, by repeating the first energy transfer state, the stop state, and the second energy transfer state, the AC current of battery B1 and the AC current of battery B2 can each be measured. This control method is useful when the voltage of battery B1 and the voltage of battery B2 are nearly the same.

In addition, part or all of drive measurement circuit 4 and part or all of drive measurement circuit 5 in embodiment 3 can be integrated into integrated circuits, thereby enabling further miniaturization and versatility of the device.

(Fourth embodiment)
In the third embodiment, the series-connected batteries B1 and B2 have approximately the same voltage. Therefore, in order to charge and discharge the capacitor 30, which is a storage element, during the H period of the control signal Vs, a switching operation is repeated in which the capacitor 30 is charged from the two series-connected batteries using the frequency-divided signal Vs1 and then discharged to one of the batteries. On the other hand, if the voltages of the batteries B1 and B2 are different, for example, if the voltage of the battery B1 is higher than the voltage of the battery B2, the basic configuration of the impedance measurement device 3 similar to that shown in FIG. 7 can be used to repeat the switching operation in which the capacitor 30 is charged from the battery B1 and then discharged to the battery B2.

The impedance measuring device according to the fourth embodiment described below has the same basic configuration as shown in FIG. 7, but to distinguish it from the impedance measuring device 3 according to the third embodiment, the drive measurement circuit 4, drive measurement circuit 5, and communication unit 6 in FIG. 7 will be referred to as drive measurement circuit 4A, drive measurement circuit 5A, and communication unit 6A, respectively.

FIG. 10 is a circuit diagram showing an example of the drive control units 43A and 53A of the impedance measuring device according to embodiment 4. FIG. 10 shows the internal configuration of the drive control unit 43A of the drive measurement circuit 4A, the drive control unit 53A of the drive measurement circuit 5A, and part of the communication unit 6A. In FIG. 10, the drive control unit 43A differs from the drive control unit 43 of FIG. 8 in that it does not have the frequency divider circuit 431, the frequency-divided signal Vs1, the inverter 433, and the OR circuit 434, and the AND circuit 432 has been reconfigured to be an AND circuit 432A. Furthermore, the communication unit 6A, which shares signals with the drive control unit 53A, does not have the frequency-divided signal Vs1, so one level shift circuit is removed compared to the communication unit 6 of FIG. 8. Furthermore, the drive control unit 53A differs from the drive control unit 53 of FIG. 8 in that it does not have the inverter 531 and the OR circuit 534, and the AND circuit 532 has been reconfigured to be an AND circuit 532A.

Oscillator 430 is the same as in Figure 8 and outputs a reference clock CK0 with a duty cycle of 50% that sets the switching period. The reference clock CK0 and a control signal Vs from the higher-level system 200 are input to AND circuit 432A. The output of AND circuit 432A is input to AND circuit 439, and the output of AND circuit 439 becomes drive signal Vg3 that drives the third switching element 31. An inverted signal obtained from the output of AND circuit 432A via inverter 435 becomes drive signal Vg4 that drives the fourth switching element 32 via AND circuit 440.

The configuration is the same as in Figure 8, in which the abnormality signal Fail1 from the abnormality detection circuit 436 is input to the AND circuit 438 together with the enable signal EN via the NOR circuit 437, and the output of the AND circuit 438 is input to the AND circuits 439 and 440. That is, if there is no abnormality and a measurement instruction is received from the upper system 200, when the control signal Vs is at H level, the third switching element 31 and the fourth switching element 32 are driven alternately on and off in accordance with the reference clock CK0, and when the control signal Vs is at L level, the third switching element 31 is turned off and the fourth switching element 32 is turned on.

Although not shown, a dead time is provided during which the normal drive signal Vg3 and the drive signal Vg4 are both turned off at the same time, so that the third switching element 31 and the fourth switching element 32 are not turned on at the same time, just like in Figure 8.

As shown in the drive control unit 53A in Figure 10, the reference clock CK0 and control signal Vs are input to the AND circuit 532A. Here, the reference clock CK0 is obtained from the drive control unit 43A via a level shift circuit in the communication unit 6A, and the control signal Vs is input from the higher-level system 200. The control signal Vs input to the drive measurement circuit 4 and the control signal Vs input to the drive measurement circuit 5 are signals of the same logic, but one of them is level-shifted. The output of the AND circuit 532A is input to the AND circuit 539, and the output of the AND circuit 539 becomes the drive signal Vg6 that drives the sixth switching element 35. The inverted signal obtained from the output of the AND circuit 532A via the inverter 535 becomes the drive signal Vg5 that drives the fifth switching element 34 via the AND circuit 540. The drive signals Vg5 and Vg6 have been swapped compared to Figure 8.

The configuration is the same as in Figure 8, in which the abnormality signal Fail2 from the abnormality detection circuit 536 is input to the AND circuit 538 together with the enable signal EN via the NOR circuit 537, and the output of the AND circuit 538 is input to the AND circuits 539 and 540. That is, if there is no abnormality and a measurement instruction is received from the upper system 200, when the control signal Vs is at H level, the fifth switching element 34 and the sixth switching element 35 are driven alternately on and off in accordance with the reference clock CK0, and when the control signal Vs is at L level, the sixth switching element 35 is turned off and the fifth switching element 34 is turned on.

Although not shown, a dead time is provided in which the normal drive signal Vg5 and the drive signal Vg6 are both turned off at the same time, so that the fifth switching element 34 and the sixth switching element 35 are not turned on at the same time. As in Figure 8, a delay time equivalent to the dead time is provided in the rising edge of each drive signal.

FIG. 11 is a timing chart showing an example of the operation of the impedance measuring device according to embodiment 4. FIG. 11 is a timing chart showing the operation of the main components of drive control unit 43A and drive control unit 53A, and shows reference clock CK0, control signal Vs, drive signals Vg3, Vg4, Vg5, Vg6, detection voltage Vc1, detection voltage Vc2, and the positive electrode potential VP and negative electrode potential VN of capacitor 30. Although not shown, enable signal EN is at H level, and abnormality signals Fail1 and Fail2 are both at L level. Detection voltage Vc1 corresponds to current I1 flowing through battery B1 and third switching element 31, and detection voltage Vc2 corresponds to current I2 flowing through battery B2 and fifth switching element 34. Below, we will use FIG. 11 to explain the operation of the impedance measuring device according to embodiment 4 in passing high-frequency current pulses through batteries B1 and B2.

As shown in Figure 11, during period T0, the control signal Vs is at L level, so that the drive signals Vg3 is at L level, Vg4 is at H level, Vg5 is at H level, and Vg6 is at L level. The third switching element 31 is in the OFF state and the fourth switching element 32 is in the ON state, so the positive electrode potential VP of capacitor 30 is fixed to the negative electrode potential VB of battery B1, and the sixth switching element 35 is in the OFF state and the fifth switching element 34 is in the ON state, so the negative electrode potential VN of capacitor 30 is fixed to the negative electrode potential of battery B2. The voltage of capacitor 30 becomes the voltage of battery B2, so no battery current flows, and both the detection voltage Vc1 and the detection voltage Vc2 are zero.

At time t0, when period T1 begins during which control signal Vs becomes H level, the drive signals Vg3 and Vg6 become the reference clock CK0, and Vg4 and Vg5 become the inverse of reference clock CK0, resulting in a switching operation in which the third switching element 31 and the fourth switching element 32 alternately turn on and off, and the fifth switching element 34 and the sixth switching element 35 alternately turn on and off. Between times t0 and t1, drive signals Vg3 and Vg6 are H level, so the third switching element 31 and the sixth switching element 35 are in the ON state, and current I1 flows, charging capacitor 30 to the voltage of battery B1.

Next, from time t1 to t2, drive signal Vg4 and drive signal Vg5 are at H level, so fourth switching element 32 and fifth switching element 34 are turned on, current I2 flows, and capacitor 30 is discharged to the voltage of battery B2. Thus, during period T1, battery B1 repeatedly discharges at the frequency of reference clock CK0, and battery B2 repeatedly charges at the frequency of reference clock CK0.

At time t3, when period T2 begins and the control signal Vs goes low, the drive signals Vg3 goes low, Vg4 goes high, Vg5 goes high, and Vg6 goes low, the same as in period T0.

As described above, in accordance with the control signal Vs, battery B1 is repeatedly discharged and battery B2 is repeatedly charged by a pulse current to capacitor 30. Current I1 of battery B1 is converted to detection voltage Vc1 by detection resistor 33 and input to current measurement unit 41 of drive measurement circuit 4A, while current I2 of battery B2 is converted to detection voltage Vc2 by detection resistor 36 and input to current measurement unit 51 of drive measurement circuit 5A. During AC impedance measurement, the impedance measurement device of embodiment 4 repeatedly performs a switching operation to discharge battery B1 and charge battery B2 via capacitor 30 while the control signal Vs is at a high level, and stops charging and discharging through the switching operation while the control signal Vs is at a low level. Compared to conventional methods that use a resistive element to pass a superimposed current through the battery, this method reduces losses and achieves switching operation with a stable voltage across capacitor 30.

As described above, the drive control units 43A and 53A may control the third switching element 31, the fourth switching element 32, the fifth switching element 34, and the sixth switching element 35 to alternate between a first energy transfer state and a stopped state at a period corresponding to the measurement frequency. Here, the first energy transfer state is a state in which, as shown in period T1 in FIG. 11 , the third switching element 31 and the fourth switching element 32 are alternately turned on at a frequency higher than the measurement frequency, the fifth switching element 34 and the sixth switching element 35 are alternately turned on at a frequency higher than the measurement frequency, the switching phase of the third switching element 31 and the switching phase of the sixth switching element 35 are in phase, the switching phase of the fourth switching element 32 and the switching phase of the fifth switching element 34 are in phase, and battery B1 is repeatedly discharged and battery B2 is repeatedly charged, or battery B1 is repeatedly charged and battery B2 is repeatedly discharged, via capacitor 30. The stopped state is a state in which batteries B1 and B2 are not being charged or discharged, as shown in periods T0 and T2 in Figure 11.

Battery B1 is repeatedly discharged, so the current of battery B1 can be measured, and battery B2 is repeatedly charged, so the current of battery B2 can be measured. Therefore, by repeating the first energy transfer state and the stopped state, the AC current of battery B1 and the AC current of battery B2 can be measured. This control method is useful when the voltage of battery B1 is higher than the voltage of battery B2. When the voltage of battery B1 is lower than the voltage of battery B2, the above charge/discharge relationship is reversed.

In addition, part or all of drive measurement circuit 4A and part or all of drive measurement circuit 5A in embodiment 4 can be integrated into integrated circuits, thereby enabling further miniaturization and versatility of the device.

(Other embodiments)
As described above, the embodiments have been described as examples of the technology according to the present disclosure. However, the technology according to the present disclosure is not limited to these, and can be applied to embodiments in which appropriate modifications, substitutions, additions, omissions, etc. are made. For example, the following modifications are also included in one embodiment of the present disclosure.

For example, the present disclosure can be realized not only as a drive and measurement circuit, but also as a drive and measurement method that includes steps (processing) performed by the components that make up the drive and measurement circuit.

Figure 12 is a flowchart showing an example of a drive measurement method according to another embodiment.

The driving measurement method is a driving measurement method for controlling an impedance measuring device that measures the AC impedance of a first battery and a second battery connected in series. The impedance measuring device includes a storage element that stores or releases electrical energy, a switching circuit consisting of a plurality of switching elements that intermittently transfers electrical energy between the first battery and the second battery via the storage element, and a current detection means that detects the current of the first battery and the current of the second battery. As shown in Figure 12, the driving measurement method includes receiving a measurement instruction signal including information on the measurement frequency from a higher-level system that has the function of calculating the AC impedance. The method includes a power receiving step (step S11) for receiving power from a power storage element, a driving step (step S12) for driving a plurality of switching elements so as to periodically change the state of electrical energy transfer via the power storage element in accordance with the measurement frequency, a current measurement step (step S13) for measuring the current of the first battery and the current of the second battery based on the detection results of the current detection means, a voltage measurement step (step S14) for measuring the voltage of the first battery and the voltage of the second battery, and an AC detection step (step S15) for measuring AC voltage and AC current according to the measurement frequency based on the measurement results of the voltage measurement step and the current measurement step, and outputting the results to a higher-level system.

For example, the present disclosure can be realized as a program that causes a computer (processor) to execute the steps included in the drive measurement method. Furthermore, the present disclosure can be realized as a non-transitory computer-readable recording medium, such as a CD-ROM, on which the program is recorded.

For example, if the present disclosure is realized as a program (software), each step is performed by running the program using hardware resources such as a computer's CPU, memory, and input/output circuits. In other words, each step is performed by the CPU obtaining data from memory or input/output circuits, etc., performing calculations, and outputting the calculation results to memory or input/output circuits, etc.

In the above-described embodiments, each component included in the drive measurement circuit may be configured with dedicated hardware, or may be realized by executing a software program appropriate for each component. Each component may also be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

Some or all of the functions of the drive measurement circuit according to the above embodiments are typically realized as an LSI, which is an integrated circuit. These may be individually implemented on a single chip, or some or all of them may be integrated into a single chip. Furthermore, the integrated circuit is not limited to an LSI, but may also be realized using a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array), which can be programmed after LSI manufacture, or a reconfigurable processor, which can reconfigure the connections and settings of circuit cells within an LSI, may also be used.

Furthermore, if advances in semiconductor technology or other derivative technologies result in the emergence of integrated circuit technology that can replace LSI, that technology may naturally be used to integrate the various components included in the drive and measurement circuit.

In addition, this disclosure also includes forms obtained by applying various modifications to the embodiments that would occur to those skilled in the art, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope of the spirit of this disclosure.

(Additional Note)
The above description of the embodiments discloses the following techniques.

(Technology 1) A drive measurement circuit for controlling an impedance measurement device that measures the AC impedance of a first battery and a second battery connected in series, the impedance measurement device comprising: a storage element that stores or releases electrical energy; a switching circuit consisting of a plurality of switching elements that intermittently transfers electrical energy between the first battery and the second battery via the storage element; and a current detection means that detects the current of the first battery and the current of the second battery, and the drive measurement circuit determines the AC impedance of the first battery based on the detection result of the current detection means. A drive measurement circuit comprising: a current measurement unit that measures the current of the first battery and the current of the second battery; a voltage measurement unit that measures the voltage of the first battery and the voltage of the second battery; an AC detection unit that receives a measurement instruction signal including measurement frequency information from a host system having a function for calculating AC impedance, and measures AC voltage and AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement unit and the current measurement unit, and outputs these to the host system; and a drive control unit that drives the multiple switching elements so as to periodically change the state of electrical energy transfer through the storage elements in accordance with the measurement frequency.

In this way, the state of electrical energy transfer between the first battery and the second battery is changed periodically in accordance with the measurement frequency, making it possible to measure the AC voltage and AC current in accordance with the measurement frequency, and to measure the AC impedance of the first battery and the second battery. In this case, the state of electrical energy transfer can be changed via a single storage element, such as an inductor or capacitor, provided in the impedance measuring device, eliminating the need for both an inductor and a storage device (capacitor) as in the method disclosed in Patent Document 2. This makes it possible to miniaturize the impedance measuring device.

Furthermore, since AC impedance can be measured regardless of the voltage of the first battery and the voltage of the second battery, usage restrictions are relaxed. Furthermore, since current flows constantly between the first battery and the second battery, charging and discharging without any downtime, measurement time is shortened and measurement can be performed continuously.

(Technology 2) A drive measurement circuit according to Technology 1, in which the first battery and the second battery are each composed of two or more battery cells, and the voltage measurement unit simultaneously measures the voltages of the two or more battery cells.

This allows the voltage of the first battery and the voltage of the second battery to be measured in a short period of time.

(Technology 3) A drive and measurement circuit according to Technology 1 or 2, in which the storage element is an inductor, the switching circuit has a first switching element that forms a first loop together with the first battery and the inductor, and a second switching element that forms a second loop together with the second battery and the inductor, and the drive control unit alternately turns on the first switching element and the second switching element at a frequency higher than the measurement frequency.

By alternately turning on the first switching element and the second switching element at a frequency higher than the measurement frequency, the time that current flows through the inductor at one time can be shortened. In other words, since it is difficult for a large current to flow through the inductor, the inductor can be made smaller, which in turn makes it possible to make the impedance measurement device more compact.

(Technology 4) A drive and measurement circuit according to Technology 3, wherein the current detection means includes a first detection resistor connected between the first battery and the first switching element, and a second detection resistor connected between the second battery and the second switching element.

In this way, the current of the first battery can be detected by detecting the current flowing through the first detection resistor, and the current of the second battery can be detected by detecting the current flowing through the second detection resistor.

(Technology 5) A drive and measurement circuit according to Technology 3, wherein the current detection means includes one of a first detection resistor connected between the first battery and the first switching element and a second detection resistor connected between the second battery and the second switching element, and a third detection resistor connected in series with the inductor.

As a result, the current of one of the first and second batteries can be detected by detecting the current flowing through one of the first and second detection resistors. Furthermore, since the current flowing through the third detection resistor is the difference between the current flowing through the second battery and the current flowing through the first battery, the current of the other of the first and second batteries can be detected by calculating the sum of the current flowing through the one detection resistor and the current flowing through the third detection resistor.

(Technology 6) A drive measurement circuit described in any one of Technologies 3 to 5, wherein the drive control unit controls the on-time of the first switching element and the on-time of the second switching element so as to repeat, at a period corresponding to the measurement frequency, a first energy transfer state in which a discharge current is flowed from the first battery when the first switching element is on and a charge current is flowed to the second battery when the second switching element is on, and a second energy transfer state in which a discharge current is flowed from the second battery when the second switching element is on and a charge current is flowed to the first battery when the first switching element is on.

In this way, by lengthening the on time of the second switching element, it is possible to start flowing a discharge current from the second battery, thereby switching from the first energy transfer state to the second energy transfer state. Furthermore, by lengthening the on time of the first switching element, it is possible to start flowing a discharge current from the first battery, thereby switching from the second energy transfer state to the first energy transfer state.

(Technology 7) A drive measurement circuit according to Technology 6, wherein the drive control unit limits the peak value of the discharge current from the first battery to a predetermined value in the first energy transfer state, and limits the peak value of the discharge current from the second battery to a predetermined value in the second energy transfer state.

This allows the discharge current from the first battery and the discharge current from the second battery to be limited, thereby suppressing switching losses that occur during switching.

(Technology 8) A drive measurement circuit according to any one of Technologies 3 to 7, wherein the switching circuit has a current interruption means connected in series with the inductor, and the drive control unit interrupts the current flowing through the current interruption means when the detection result of the current detection means exceeds a predetermined amount.

This allows the current to be cut off when an overcurrent occurs.

(Technology 9) A drive and measurement circuit according to Technology 1 or 2, wherein the storage element is a capacitor, and the switching circuit has a third switching element connected between the positive electrode of the first battery and the positive electrode of the capacitor, a fourth switching element connected between the negative electrode of the first battery and the positive electrode of the capacitor, a fifth switching element connected between the negative electrode of the second battery and the negative electrode of the capacitor, and a sixth switching element connected between the positive electrode of the second battery and the negative electrode of the capacitor, and the drive control unit alternately turns on the third switching element and the fourth switching element at a frequency higher than the measurement frequency and alternately turns on the fifth switching element and the sixth switching element at a frequency higher than the measurement frequency, so that the fourth switching element and the sixth switching element are not simultaneously turned on.

In this way, by alternately turning on the third switching element and the fourth switching element at a frequency higher than the measurement frequency, and by alternately turning on the fifth switching element and the sixth switching element at a frequency higher than the measurement frequency, it is possible to shorten the time it takes to store charge in the capacitor at one time. In other words, since a capacitor with a large capacity is no longer necessary, the capacitor can be made smaller, which in turn makes it possible to make the impedance measurement device more compact.

(Technology 10) A drive and measurement circuit according to Technology 9, wherein the current detection means includes a first detection resistor connected between the first battery and the third switching element, and a second detection resistor connected between the second battery and the fifth switching element.

In this way, the current of the first battery can be detected by detecting the current flowing through the first detection resistor, and the current of the second battery can be detected by detecting the current flowing through the second detection resistor.

(Technology 11) The drive control unit fixes the third switching element to the on state, fixes the fourth switching element to the off state, and alternately turns on the fifth switching element and the sixth switching element at a frequency higher than the measurement frequency, repeating a first energy transfer state in which the first battery is charged when the sixth switching element is on and a first battery and a second battery are discharged when the fifth switching element is on; and a second energy transfer state in which the fifth switching element is fixed to the on state, fixes the sixth switching element to the off state, and alternately turns on the fifth switching element and the sixth switching element at a frequency higher than the measurement frequency, repeating a first energy transfer state in which the fifth switching element is fixed to the on state, fixes the sixth switching element to the off state, and alternately turns on the third switching element and the sixth switching element at a frequency higher than the measurement frequency, repeating a first energy transfer state in which the fifth switching element is fixed to the on state, fixes the sixth switching element to the off state, The drive measurement circuit described in technology 9 or 10 controls the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element so as to alternately turn on the third switching element and the fourth switching element at a frequency higher than the measurement frequency, and to repeat a second energy transfer state in which the first battery and the second battery are discharged when the third switching element is on and the second battery is charged when the fourth switching element is on, and a stop state in which the first battery and the second battery are not charged or discharged, in a cycle corresponding to the measurement frequency.

According to this, in the first energy transfer state, the first battery repeatedly charges and discharges, so the average current of the first battery in the first energy transfer state is nearly zero, and the current of the first battery cannot be measured. On the other hand, in the second energy state, the first battery repeatedly discharges, so the current of the first battery can be measured. Also, in the second energy transfer state, the second battery repeatedly charges and discharges, so the average current of the second battery in the second energy transfer state is nearly zero, and the current of the second battery cannot be measured. On the other hand, in the first energy state, the second battery repeatedly discharges, so the current of the second battery can be measured. Therefore, by repeating the first energy transfer state, the stop state, and the second energy transfer state, the AC current of the first battery and the AC current of the second battery can each be measured. Note that this control method is useful when the voltage of the first battery and the voltage of the second battery are nearly the same.

(Technology 12) The drive measurement circuit of claim 9 or 10, wherein the drive control unit alternately turns on the third switching element and the fourth switching element at a frequency higher than the measurement frequency, alternately turns on the fifth switching element and the sixth switching element at a frequency higher than the measurement frequency, makes the switching phase of the third switching element the same as the switching phase of the sixth switching element, makes the switching phase of the fourth switching element the same as the switching phase of the fifth switching element, and controls the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element to alternately turn on the fifth switching element at a frequency higher than the measurement frequency, and controls the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element to alternately turn on the fifth switching element at a frequency higher than the measurement frequency, and controls the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element to alternately turn on the fifth switching element at a frequency higher than the measurement frequency, and controls the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element to alternately turn on the fifth switching element at a frequency higher than the measurement frequency, and controls the fourth switching element and the sixth switching element to alternately turn on the fifth switching element at a frequency higher than the measurement frequency, and controls the fourth switching element and the fifth ...

In this way, the current of the first battery can be measured because the first battery is repeatedly discharged, and the current of the second battery can be measured because the second battery is repeatedly charged. Therefore, by repeating the first energy transfer state and the stopped state, the AC current of the first battery and the AC current of the second battery can each be measured. Note that this control method is useful when the voltage of the first battery is higher than the voltage of the second battery.

(Technology 13) A drive measurement circuit according to any one of Technologies 1 to 12, in which at least the current measurement unit, the voltage measurement unit, the AC detection unit, and the drive control unit are integrated into an integrated circuit.

In this way, the current measurement unit, voltage measurement unit, AC detection unit, and drive control unit may be integrated into an integrated circuit.

(Technology 14) An impedance measuring device for measuring the AC impedance of a first battery and a second battery connected in series, comprising: a storage element for storing or releasing electrical energy; a switching circuit consisting of a plurality of switching elements for intermittently transferring electrical energy between the first battery and the second battery via the storage element; a current detection means for detecting the current of the first battery and the current of the second battery; and a drive measurement circuit, wherein the drive measurement circuit comprises: a current measurement unit for measuring the current of the first battery and the current of the second battery based on the detection results of the current detection means; a voltage measurement unit for measuring the voltage of the first battery and the voltage of the second battery; an AC detection unit for receiving a measurement instruction signal including information on a measurement frequency from a higher-level system having the function of calculating AC impedance, and measuring an AC voltage and an AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement unit and the current measurement unit and outputting them to the higher-level system; and a drive control unit for driving the plurality of switching elements to periodically change the state of transfer of electrical energy via the storage element according to the measurement frequency.

This makes it possible to provide a compact impedance measuring device.

(Technology 15) An impedance measuring device that measures the AC impedance of a first battery and a second battery connected in series, a drive measurement circuit for controlling the impedance measuring device, and a host system having the function of calculating the AC impedance, wherein the impedance measuring device comprises a storage element that stores or releases electrical energy, a switching circuit consisting of a plurality of switching elements that intermittently transfers electrical energy between the first battery and the second battery via the storage element, and a current detection means that detects the current of the first battery and the current of the second battery, and the drive measurement circuit is An impedance measurement system comprising: a current measurement unit that measures the current of the first battery and the current of the second battery based on the detection results of the current detection means; a voltage measurement unit that measures the voltage of the first battery and the voltage of the second battery; an AC detection unit that receives a measurement instruction signal including measurement frequency information from the upper system and measures AC voltage and AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement unit and the current measurement unit, and outputs the measured values to the upper system; and a drive control unit that drives the multiple switching elements so as to periodically change the state of electrical energy transfer through the storage elements according to the measurement frequency.

This allows for the provision of a compact impedance measurement system.

(Technology 16) A driving measurement method for controlling an impedance measurement device that measures the AC impedance of a first battery and a second battery connected in series, the impedance measurement device comprising: a storage element that stores or releases electrical energy; a switching circuit consisting of a plurality of switching elements that intermittently transfers electrical energy between the first battery and the second battery via the storage element; and a current detection means that detects the current of the first battery and the current of the second battery, and the driving measurement method includes receiving measurement information including information on the measurement frequency from a host system having the function of calculating AC impedance. A driving and measurement method including: a power receiving step of receiving a constant instruction signal; a driving step of driving the multiple switching elements so as to periodically change the state of electrical energy transfer through the storage elements in accordance with the measurement frequency; a current measurement step of measuring the current of the first battery and the current of the second battery based on the detection results of the current detection means; a voltage measurement step of measuring the voltage of the first battery and the voltage of the second battery; and an AC detection step of measuring AC voltage and AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement step and the measurement results of the current measurement step, and outputting the results to the upper system.

This provides a driving measurement method that enables the impedance measurement device to be miniaturized.

This disclosure is useful as an impedance measurement device for diagnosing battery degradation.

REFERENCE SIGNS LIST 1, 1A, 3 Impedance measuring device 2, 2A, 4, 4A, 5, 5A Drive and measurement circuit 6, 6A, 224 Communication unit 11 First switching element 12 Second switching element 13 Current interruption means 14 Inductor 15, 16, 17, 33, 36 Detection resistor 20, 40, 50 Voltage measurement unit 21, 21A, 41, 51 Current measurement unit 22, 42, 52 AC detection unit 23, 43, 43A, 53, 53A Drive control unit 30 Capacitor 31 Third switching element 32 Fourth switching element 34 Fifth switching element 35 Sixth switching element 100 Impedance measurement system 200 Upper system 210 Adder 220 Signal generation unit 221 Conversion unit 222 Integration unit 223 Holding unit 230, 430 Oscillator 231, 232 Reference voltage source 233, 234 Comparator 235, 434, 534 OR circuit 236 SR latch 237, 238 Switch circuit 239, 436, 536 Abnormality detection circuit 240, 433, 435, 531, 535 Inverter 241, 242, 243, 432, 432A, 438, 439, 440, 532, 532A, 538, 539, 540 AND circuit 431 Frequency divider circuit 437, 537 NOR circuit B1, B2 Battery

Claims (16)

A driving measurement circuit for controlling an impedance measurement device that measures AC impedance of a first battery and a second battery connected in series, comprising:
The impedance measuring device is
a storage element that stores or releases electrical energy;
a switching circuit including a plurality of switching elements for intermittently transferring electrical energy between the first battery and the second battery via the storage element;
a current detection means for detecting a current of the first battery and a current of the second battery;
The drive and measurement circuit includes:
a current measuring unit that measures the current of the first battery and the current of the second battery based on the detection result of the current detecting means;
a voltage measuring unit that measures the voltage of the first battery and the voltage of the second battery;
an AC detection unit that receives a measurement instruction signal including information on a measurement frequency from a host system having a function of calculating AC impedance, measures an AC voltage and an AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement unit and the measurement results of the current measurement unit, and outputs the measured values to the host system;
a drive control unit that drives the plurality of switching elements so as to periodically change a transfer state of electric energy via the storage element in accordance with the measurement frequency;
A drive and measurement circuit comprising: the first battery and the second battery each include two or more battery cells;
The drive measurement circuit according to claim 1 , wherein the voltage measurement unit simultaneously measures the voltages of the two or more battery cells. the storage element is an inductor,
the switching circuit includes a first switching element that forms a first loop together with the first battery and the inductor, and a second switching element that forms a second loop together with the second battery and the inductor;
3. The drive and measurement circuit according to claim 1, wherein the drive control section alternately turns on the first switching element and the second switching element at a frequency higher than the measurement frequency. The drive measurement circuit of claim 3, wherein the current detection means includes a first detection resistor connected between the first battery and the first switching element, and a second detection resistor connected between the second battery and the second switching element. The drive measurement circuit of claim 3, wherein the current detection means includes one of a first detection resistor connected between the first battery and the first switching element and a second detection resistor connected between the second battery and the second switching element, and a third detection resistor connected in series with the inductor. The drive control unit
a first energy transfer state in which a discharge current flows from the first battery when the first switching element is on and a charge current flows to the second battery when the second switching element is on are repeated;
a second energy transfer state in which a discharge current flows from the second battery when the second switching element is on and a charge current flows to the first battery when the first switching element is on are repeated;
6. The drive measurement circuit according to claim 3, wherein the ON time of the first switching element and the ON time of the second switching element are controlled so that the above-mentioned is repeated at a period corresponding to the measurement frequency. The drive measurement circuit of claim 6, wherein the drive control unit limits the peak value of the discharge current from the first battery to a predetermined value in the first energy transfer state, and limits the peak value of the discharge current from the second battery to a predetermined value in the second energy transfer state. The drive measurement circuit described in any one of claims 3 to 7, wherein the switching circuit has a current interruption means connected in series with the inductor, and the drive control unit interrupts the current flowing through the current interruption means when the detection result of the current detection means exceeds a predetermined amount. the storage element is a capacitor,
the switching circuit includes a third switching element connected between the positive electrode of the first battery and the positive electrode of the capacitor, a fourth switching element connected between the negative electrode of the first battery and the positive electrode of the capacitor, a fifth switching element connected between the negative electrode of the second battery and the negative electrode of the capacitor, and a sixth switching element connected between the positive electrode of the second battery and the negative electrode of the capacitor;
3. The drive measurement circuit according to claim 1, wherein the drive control unit alternately turns on the third switching element and the fourth switching element at a frequency higher than the measurement frequency, and alternately turns on the fifth switching element and the sixth switching element at a frequency higher than the measurement frequency, so that the fourth switching element and the sixth switching element are not simultaneously turned on. The drive measurement circuit of claim 9, wherein the current detection means includes a first detection resistor connected between the first battery and the third switching element, and a second detection resistor connected between the second battery and the fifth switching element. The drive control unit
a first energy transfer state in which the third switching element is fixed to an ON state, the fourth switching element is fixed to an OFF state, and the fifth switching element and the sixth switching element are alternately turned ON at a frequency higher than the measurement frequency, and the first battery is repeatedly charged when the sixth switching element is ON, and the first battery and the second battery are repeatedly discharged when the fifth switching element is ON;
a second energy transfer state in which the fifth switching element is fixed to an ON state, the sixth switching element is fixed to an OFF state, and the third switching element and the fourth switching element are alternately turned ON at a frequency higher than the measurement frequency, thereby repeatedly discharging the first battery and the second battery when the third switching element is ON and charging the second battery when the fourth switching element is ON;
a stop state in which the first battery and the second battery are not charged or discharged;
11. The drive measurement circuit according to claim 9, wherein the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element are controlled so that the above-mentioned operation is repeated at a period corresponding to the measurement frequency. The drive control unit
a first energy transfer state in which the third switching element and the fourth switching element are alternately turned on at a frequency higher than the measurement frequency, the fifth switching element and the sixth switching element are alternately turned on at a frequency higher than the measurement frequency, the switching phase of the third switching element and the switching phase of the sixth switching element are the same, the switching phase of the fourth switching element and the switching phase of the fifth switching element are the same, and the first battery is repeatedly discharged and the second battery is repeatedly charged via the capacitor, or the first battery is repeatedly charged and the second battery is repeatedly discharged;
a stop state in which the first battery and the second battery are not charged or discharged;
11. The drive measurement circuit according to claim 9, wherein the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element are controlled so that the above-mentioned operation is repeated at a period corresponding to the measurement frequency. The drive measurement circuit described in any one of claims 1 to 12, wherein at least the current measurement unit, the voltage measurement unit, the AC detection unit, and the drive control unit are integrated into an integrated circuit. An impedance measurement device for measuring AC impedance of a first battery and a second battery connected in series, comprising:
a storage element that stores or releases electrical energy;
a switching circuit including a plurality of switching elements for intermittently transferring electrical energy between the first battery and the second battery via the storage element;
a current detection means for detecting a current of the first battery and a current of the second battery;
a drive and measurement circuit;
The drive and measurement circuit includes:
a current measuring unit that measures the current of the first battery and the current of the second battery based on the detection result of the current detecting means;
a voltage measuring unit that measures the voltage of the first battery and the voltage of the second battery;
an AC detection unit that receives a measurement instruction signal including information on a measurement frequency from a host system having a function of calculating AC impedance, measures an AC voltage and an AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement unit and the measurement results of the current measurement unit, and outputs the measured values to the host system;
a drive control unit that drives the plurality of switching elements so as to periodically change a transfer state of electric energy via the storage element in accordance with the measurement frequency;
An impedance measuring device comprising: an impedance measuring device that measures the AC impedance of the first battery and the second battery that are connected in series;
a drive and measurement circuit for controlling the impedance measurement device;
a host system having a function of calculating AC impedance;
The impedance measuring device is
a storage element that stores or releases electrical energy;
a switching circuit including a plurality of switching elements for intermittently transferring electrical energy between the first battery and the second battery via the storage element;
a current detection means for detecting a current of the first battery and a current of the second battery;
The drive and measurement circuit includes:
a current measuring unit that measures the current of the first battery and the current of the second battery based on the detection result of the current detecting means;
a voltage measuring unit that measures the voltage of the first battery and the voltage of the second battery;
an AC detection unit that receives a measurement instruction signal including information on a measurement frequency from the host system, measures an AC voltage and an AC current corresponding to the measurement frequency based on the measurement results of the voltage measurement unit and the current measurement unit, and outputs the measured values to the host system;
a drive control unit that drives the plurality of switching elements so as to periodically change a transfer state of electric energy via the storage element in accordance with the measurement frequency;
An impedance measurement system comprising: 1. A driving measurement method for controlling an impedance measurement device that measures AC impedance of a first battery and a second battery connected in series, comprising:
The impedance measuring device is
a storage element that stores or releases electrical energy;
a switching circuit including a plurality of switching elements for intermittently transferring electrical energy between the first battery and the second battery via the storage element;
a current detection means for detecting a current of the first battery and a current of the second battery;
The driving measurement method includes:
a power receiving step of receiving a measurement instruction signal including information on a measurement frequency from a host system having a function of calculating AC impedance;
a driving step of driving the plurality of switching elements so as to periodically change a transfer state of electric energy via the storage element in accordance with the measurement frequency;
a current measuring step of measuring the current of the first battery and the current of the second battery based on the detection result of the current detecting means;
a voltage measuring step of measuring a voltage of the first battery and a voltage of the second battery;
an AC detection step of measuring an AC voltage and an AC current according to the measurement frequency based on the measurement results in the voltage measurement step and the current measurement step, and outputting the measured AC voltage and AC current to the host system;
A driving measurement method including: