JP7327955B2 - Lead-acid battery state detection device and lead-acid battery state detection method - Google Patents

Description

The present invention relates to a lead-acid battery state detection device and a lead-acid battery state detection method.

In Patent Document 1, when a lead-acid battery has a usage history that induces variations between cells, a predetermined function indicating the deterioration state of the lead-acid battery is corrected, so that deterioration closer to reality is performed. Techniques for obtaining status are disclosed.

JP 2017-181206 A

By the way, in lead-acid batteries for automobiles, depending on the position and direction of installation, the heat from the prime mover such as the engine or motor may raise the temperature of cells located close to them, causing temperature variations between cells. be. In such a case, the cells with different temperatures may have different internal resistance values, or the deterioration of the cells with a higher temperature may progress faster than the other cells.

However, in the technique disclosed in Patent Document 1, since there is only one temperature sensor, it is not possible to detect temperature variations as described above, so there is the problem that the state of the lead-acid battery cannot be detected accurately. be.

SUMMARY OF THE INVENTION The present invention has been made in view of the circumstances described above, and is a lead-acid battery that can accurately estimate the state of a lead-acid battery even when there is variation in temperature between the cells of the lead-acid battery. An object of the present invention is to provide a storage battery state detection device and a lead-acid battery state detection method.

In order to solve the above-mentioned problems, the present invention provides a processor in a lead-acid battery state detecting device for detecting the state of a lead-acid battery for vehicle use having an electrolytic bath partitioned into a plurality of cells, and when executed by the processor: a voltage signal from a voltage sensor that detects the terminal voltage of the lead-acid battery, and a current from a current sensor that detects the charging/discharging current of the lead-acid battery. and a temperature signal from a temperature sensor that detects temperatures at a plurality of locations in the electrolytic cell, and configures an equivalent circuit of the lead-acid battery based on the voltage signal and the current signal during discharge of the lead-acid battery. The values of the elements constituting the calculated equivalent circuit are corrected based on the temperature signals indicating the temperatures at a plurality of locations in the electrolytic cell, and the corrected element values and outputting the detected state of the lead-acid battery.
According to such a configuration, it is possible to accurately estimate the state of the lead-acid battery even when there is variation in temperature between the cells of the lead-acid battery.

In the present invention, the temperature sensors are arranged so as to be able to detect the temperature of the cells located at both ends of the electrolytic cell, and detect the temperature rise of the cells located at both ends due to the heat generated by the engine of the vehicle. Characterized by
According to such a configuration, it is possible to reduce the influence from the heat source and accurately estimate the state of the lead-acid battery.

Further, the present invention is characterized in that the temperature sensor is arranged so as to be able to detect the temperatures of the plurality of cells of the electrolytic cell, and detects a temperature rise caused by progress of deterioration of the cells.
According to such a configuration, it is possible to reduce the influence of progress of deterioration and accurately estimate the state of the lead-acid battery.

Further, the present invention is characterized in that the values of the elements of the equivalent circuit are corrected based on the value obtained by time-integrating the temperature signal from the temperature sensor.
According to such a configuration, it is possible to accurately correct the values of the elements of the equivalent circuit based on the past temperature history.

Further, the present invention is characterized in that the values of the elements of the equivalent circuit are distributed to the respective cells based on the values obtained by time-integrating the temperature signal.
With such a configuration, it is possible to accurately obtain the values of the elements of each cell.

Further, the present invention is characterized in that the dischargeable capacity of each cell is corrected based on the values of the elements distributed to each cell.
With such a configuration, it is possible to accurately obtain the dischargeable capacity of each cell.

Further, according to the present invention, the temperature signal is received from the temperature sensor arranged one by one for each cell, and the values of the elements of the equivalent circuit are corrected based on the temperature signal from each cell. characterized by
With such a configuration, it is possible to accurately obtain the values of the elements of each cell.

The present invention also receives the temperature signals from at least two temperature sensors spaced apart in the vertical direction of the electrolytic cell, and determines the vertical temperature difference of the electrolytic cell based on the temperature signals. The temperature difference is detected, the degree of stratification of the electrolyte is detected based on the detected temperature difference, and the value of the element is corrected based on the degree of stratification.
With such a configuration, it is possible to accurately estimate the state of the lead-acid battery in consideration of the effects of stratification.

Further, the present invention is characterized in that the temperature sensor is arranged inside a cover that accommodates the lead-acid battery.
According to such a configuration, it is possible to accurately estimate the state of the lead-acid battery while reducing the influence of an external heat source.

The present invention also provides a lead-acid battery condition detection method for detecting the condition of a lead-acid battery for vehicle use having an electrolytic bath divided into a plurality of cells, wherein a voltage signal from a voltage sensor for detecting the terminal voltage of the lead-acid battery and , a current signal from a current sensor for detecting the charging and discharging current of said lead-acid battery, and a temperature signal from at least two temperature sensors for detecting the temperature of cells located at opposite ends of said electrolytic cell, by a system having a processor. Then, based on the voltage signal and the current signal during discharging of the lead-acid battery, the system calculates the values of the elements that make up the equivalent circuit of the lead-acid battery, and the values of the elements that make up the calculated equivalent circuit. correcting the element value by the system based on the received temperature difference between the cells located at both ends, detecting the state of the lead-acid battery by the system based on the corrected element value; The system is characterized in that the detected state of the lead-acid battery is output by the system.
According to such a method, it is possible to accurately estimate the state of the lead-acid battery even when there is variation in temperature between the cells of the lead-acid battery.

According to the present invention, there is provided a lead-acid battery state detection device and a lead-acid battery state detection method capable of accurately estimating the state of a lead-acid battery even when there is variation in temperature between cells of the lead-acid battery. It becomes possible to

It is a figure which shows the structural example of the lead acid battery state detection apparatus which concerns on embodiment of this invention. FIG. 2 is a diagram showing a configuration example of a lead-acid battery shown in FIG. 1; FIG. 2 is a block diagram showing a detailed configuration example of a control unit in FIG. 1; FIG. 3 is a diagram showing an example of an equivalent circuit of the lead-acid battery shown in FIG. 2; FIG. FIG. 5 is a diagram showing a relationship between a conventional inter-terminal resistance, a resistance value of each cell, and an estimated capacity; It is a figure which shows the relationship between the resistance between terminals, the resistance value of each cell, and estimated capacity|capacitance in this embodiment. FIG. 4 is a flowchart for explaining an example of processing executed when an engine is started in an embodiment of the present invention; FIG. 4 is a flowchart for explaining an example of a process executed when an engine is stopped in an embodiment of the present invention; It is a figure which shows the other example of arrangement|positioning of a temperature sensor. It is a figure which shows the example of the contour line of the temperature of a lead storage battery. It is a figure which shows the other example of arrangement|positioning of a temperature sensor. It is a figure which shows the other example of arrangement|positioning of a temperature sensor. It is a figure which shows the other example of arrangement|positioning of a temperature sensor. It is a figure which shows the example which arrange|positions a temperature sensor to a cover.

Next, embodiments of the present invention will be described.

(A) Description of Configuration of Embodiment of the Invention FIG. 1 is a diagram showing a power supply system of a vehicle having a lead-acid battery state detection device according to an embodiment of the invention. In this figure, the lead-acid battery state detection device 1 has a control unit 10 as a main component, and a voltage sensor 11, a current sensor 12, temperature sensors 13-1 and 13-2, and a discharge circuit 15 are connected to the outside. , to detect the state of the lead-acid battery 14 . Note that the control unit 10, the voltage sensor 11, the current sensor 12, the temperature sensors 13-1 and 13-2, and the discharge circuit 15 are not configured separately, but a configuration in which some or all of these are combined. good too.

Here, the control unit 10 refers to outputs from the voltage sensor 11, the current sensor 12, and the temperature sensors 13-1 and 13-2, detects the state of the lead-acid battery 14, and outputs information on the detection results to the outside. In addition to outputting, the charge state of the lead-acid battery 14 is controlled by controlling the voltage generated by the alternator 16 . It should be noted that instead of the control unit 10 controlling the voltage generated by the alternator 16 to control the state of charge of the lead-acid battery 14, for example, an ECU (Electric Control Unit) (not shown) charges based on information from the control unit 10. You may make it control a state.

The voltage sensor 11 detects the terminal voltage of the lead-acid battery 14 and supplies it to the controller 10 as a voltage signal. The current sensor 12 detects the current flowing through the lead-acid battery 14 and supplies it to the control unit 10 as a current signal.

The temperature sensors 13-1 and 13-2 detect the electrolyte of the lead-acid battery 14 or the ambient temperature (for example, absolute temperature) of the lead-acid battery 14 and supply it to the controller 10 as a temperature signal. As the temperature sensors 13-1 and 13-2, for example, thermistors, resistance temperature detectors, thermocouples, and IC (Integrated Circuit) temperature sensors can be used. An infrared sensor that senses infrared rays may be used.

FIG. 2 shows a configuration example of the lead-acid battery 14 . As shown in FIG. 2, the lead-acid battery 14 has, for example, an electrolytic bath 140 partitioned into a plurality of cells 141-146. Inside the cells 141 to 146, a cathode made of lead, a separator, and an anode made of lead dioxide are stacked and arranged, and filled with an electrolytic solution. Temperature sensors 13-1 and 13-2 are arranged on surfaces 14a and 14b of cells 141 and 146 located at both ends of electrolytic bath 140, respectively. Temperature sensors 13-1 and 13-2 detect temperatures of cells 141 and 146 and output temperature signals.

The discharge circuit 15 is composed of, for example, a semiconductor switch and a resistance element connected in series. By turning on/off the semiconductor switch according to the control of the control unit 10, the lead-acid battery 14 is discharged with a desired waveform. be able to.

The alternator 16 is driven by the engine 17 to generate AC power, convert it to DC power by a rectifier circuit, and charge the lead-acid battery 14 . The alternator 16 is controlled by the controller 10 and is capable of adjusting the generated voltage.

The engine 17 is composed of, for example, a reciprocating engine such as a gasoline engine and a diesel engine, a rotary engine, or the like, and is started by a starter motor 18 to drive drive wheels through a transmission to provide propulsion to the vehicle. to generate electric power. The starter motor 18 is composed of, for example, a direct-current motor, and generates a rotational force from electric power supplied from the lead-acid battery 14 to start the engine 17 . An electric motor may be used instead of the engine 17 .

The load 19 includes, for example, an electric steering motor, a defogger, a seat heater, an ignition coil, a car audio system, a car navigation system, and the like, and operates with power supplied from the lead-acid battery 14 . In the example of FIG. 1, only the engine 17 is configured to output driving force, but a hybrid vehicle equipped with an electric motor that assists the engine 17 may be used. In the case of a hybrid vehicle, the lead-acid battery 14 activates a high-voltage system (system for driving an electric motor) composed of a lithium battery or the like, and the high-voltage system activates the engine 17 .

FIG. 3 is a diagram showing a detailed configuration example of the control unit 10 shown in FIG. As shown in this figure, the control unit 10 includes a CPU (Central Processing Unit) 10a as a processor, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication unit 10d, and an I/F (Interface) 10e. , and a bus 10f. Here, the CPU 10a controls each section based on a program 10ba stored in the ROM 10b. The ROM 10b is composed of a semiconductor memory or the like, and stores programs 10ba and the like. The RAM 10c is configured by a semiconductor memory or the like, and stores data generated when executing the program 10ba and data 10ca such as tables. The communication unit 10d communicates with an ECU (Electronic Control Unit) or the like, which is a host device, and notifies the host device of detected information or control information. The I/F 10e converts the voltage signal, the current signal, and the temperature signal supplied from the voltage sensor 11, the current sensor 12, and the temperature sensors 13-1 and 13-2 into digital signals and takes them in. 15, an alternator 16, a starter motor 18, etc., and supplies a drive current to control them. The bus 10f is a group of signal lines for interconnecting the CPU 10a, ROM 10b, RAM 10c, communication section 10d, and I/F 10e and enabling information exchange therebetween.

In addition, although one CPU 10a is provided in the example of FIG. 3, distributed processing may be executed by a plurality of CPUs. Alternatively, the CPU 10a may be replaced by a DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), or the like. Alternatively, the processing may be performed by a computer on a server using a general-purpose processor or cloud computing that executes the functions by loading a software program. In addition, although the ROM 10b and the RAM 10c are provided in FIG. 3, for example, a storage device other than these (for example, an HDD (Hard Disk Drive) which is a magnetic storage device) may be used.

(B) Description of operation of embodiment of the present invention Next, operation of the embodiment of the present invention will be described. In the following, after describing the operation of the embodiment of the present invention, the processing of the flowchart for realizing such an operation will be described.

First, the outline of the operation of the embodiment of the present invention will be described. When the ignition switch (not shown) is operated by the user to start the engine 17 of the vehicle, the CPU 10a of the control unit 10 detects the temperature output from the temperature sensors 13-1 and 13-2 via the I/F 10e. input signal.

Here, the temperature sensor 13-1 detects the temperature of the cell 141 of the electrolytic bath 140, and the temperature sensor 13-2 detects the temperature of the cell 146 of the electrolytic bath 140 and outputs it. The CPU 10a obtains the temperature θ1 indicated by the temperature signal supplied from the temperature sensor 13-1, and obtains the temperature θ2 indicated by the temperature signal supplied from the temperature sensor 13-2.

Next, the CPU 10a integrates the temperatures θ1 and θ2 over time. For example, when the temperatures θ1 and θ2 are acquired at a predetermined cycle (ΔT), the calculation result of θ1×ΔT is cumulatively added to the variable C1 (C1←C1+θ1×ΔT is calculated), and the variable C2 On the other hand, the calculation result of θ2×ΔT is cumulatively added (C2←C2+θ2×ΔT is calculated). Then, the CPU 10a stores the obtained values of C1 and C2 in the RAM 10c as data 10ca.

The above operation is repeated until the engine 17 is stopped or the temperatures of the temperature sensors 13-1 and 13-2 reach a predetermined temperature (for example, the same as the outside air temperature).

When a predetermined time (for example, several hours) has passed since the engine 17 was stopped, the CPU 10a supplies a control signal to the discharge circuit 15 via the I/F 10e to cause, for example, pulse discharge of the lead-acid battery 14. , the voltage and current signals from voltage sensor 11 and current sensor 12 . Instead of discharging by the discharge circuit 15, for example, the voltage signal and the current signal may be acquired when the engine 17 is started by the starter motor 18 or when current flows through the load 19.

Next, the CPU 10a calculates the values of the elements forming the equivalent circuit of the lead-acid battery 14. FIG. More specifically, as an equivalent circuit of the lead-acid battery 14, for example, there is an equivalent circuit shown in FIG. In the example of FIG. 4, the equivalent circuit consists of Rohm, which is a resistance component corresponding to the conductor element inside the lead-acid battery 14 and electrolyte resistance, and Rct1 and Rct2, which are resistance components corresponding to the reaction resistance of the electrode active material reaction. , and Cd1 and Cd2, which are capacitive components corresponding to the electric double layer at the interface between the electrode and the electrolyte. The CPU 10a obtains the equivalent circuit of the lead-acid battery 14 shown in FIG. 4 by learning processing or fitting processing, and calculates the values of the elements forming the equivalent circuit.

Next, the CPU 10a acquires C1 and C2 calculated during operation of the engine 17 from the RAM 10C. Then, for example, it is determined whether or not C1 and C2 differ by a predetermined threshold or more.

Here, C1 and C2 are different when, for example, the lead-acid battery 14 is placed in a place where it receives heat from the engine 17, and one of the cells 141 and 146 is close to the engine 17. when placed.

More specifically, for example, if cell 141 is positioned closer to engine 17 than cell 146, cell 141 will be hotter than cell 146 during operation of engine 17. It is time.

In such a case, in the lead-acid battery 14, a cell with a high temperature will deteriorate faster than a cell with a low temperature. Specifically, according to the Arrhenius equation, if the temperature rises by 10° C., the life is halved.

It is known that the internal resistance of the lead-acid battery 14 increases as deterioration of the cell electrodes progresses. In addition, in the lead-acid battery 14 having a plurality of cells 141 to 146, the capacity of the cell with the most advanced deterioration determines the capacity of all cells. That is, when the capacity of one cell with the most advanced deterioration is 40 Ah and the capacity of all the other cells is 50 Ah, discharge becomes impossible when the discharge of 40 Ah is completed, so 40 Ah is used as all cells. becomes capacity.

By the way, in the conventional case, as shown in the upper part of FIG. As shown, the internal resistance of all cells was estimated to be Y [Ω] (6Y/6). In addition, as shown in the lower part of FIG. 5, the capacity of each cell is assumed to be equal to X [Ah].

However, in the lead-acid battery 14 shown in the upper part of FIG. 6, if the cell on the left side of the figure is arranged closer to the engine 17 than the cell on the right side, and the deterioration progresses, As shown in the middle part of FIG. 6, the internal resistance of each cell may decrease from left to right. That is, the left cell is more deteriorated and has a larger resistance value. Also, in this case, as shown in the lower part of FIG. 6, the left cell has a smaller capacity. Specifically, the capacity of the leftmost cell is X/2 [Ah], and the capacity of the rightmost cell is X/0.4 [Ah].

In the case of FIG. 6, the capacity of the cell with the smallest capacity is the capacity of the entire cell, so X/2 [Ah] is the capacity of the entire cell.

In addition, when the temperature difference between cells is small (for example, when the lead-acid battery 14 is placed at a position sufficiently distant from the engine 17, or when it is placed near the engine 17, all the cells are arranged to have approximately the same temperature distribution), as shown in FIG. In such a case, the internal resistance and capacitance of the cell can be obtained by the same method as in the conventional method.

By comparing C1 and C2, if they do not differ by a predetermined threshold or more, for example, ABS() is a function for obtaining the absolute value in parentheses, and if the threshold is Th, ABS(1-C1/C2) When <Th (for example, Th=0.1) is satisfied, it is determined that the difference is not greater than a predetermined threshold, and the temperature between cells is determined to be substantially constant. In this case, if the internal resistance of the entire cell is 6Y, the internal resistance of each cell is determined to be Y.

On the other hand, when it is determined that the temperature between the cells is not constant (there is temperature variation) and the internal resistance of the entire cell is 6Y, the internal resistance of the cells 141 to 146 is R1 to R6. The resistors R1 to R6 can be obtained by the following formulas. Note that f1 (C1, C2) to f6 (C1, C2) are predetermined functions with C1 and C2 as variables. More specifically, f1() to f6() are f1()=f2()=f3()=f4()=f5()=f6()=1/6 when C1=C2, and If C1>C2, f1()>f2()>f3()>f4()>f5()>f6(), and if C1<C2, f1()<f2()<f3(). The function satisfies <f4()<f5()<f6(). Note that these functions can be obtained by, for example, actual measurements. Alternatively, it can be obtained using a thermal equivalent circuit of the lead-acid battery 14 (a circuit in which the object is modeled by thermal resistance and thermal capacity).

R1=6Y×f1(C1, C2) (1)
R2=6Y×f2(C1, C2) (2)
R3=6Y×f3(C1, C2) (3)
R4=6Y×f4(C1, C2) (4)
R5=6Y×f5(C1, C2) (5)
R6=6Y×f6(C1, C2) (6)

Next, the CPU 10a selects the largest value among R1 to R6, estimates the capacity of the cell based on the selected internal resistance value, and regards the capacity of the cell as the capacity of the lead-acid battery 14. presume. For example, the OCV (Open Circuit Voltage) of each cell can be calculated based on the internal resistance of each cell, and the capacity (SOC: State of Charge) of each cell can be obtained from the OCV.

The CPU 10a adjusts the voltage generated by the alternator 16 based on the cell capacity thus calculated, and controls the lead-acid battery 14 to be fully charged or nearly so. Alternatively, the CPU 10a notifies an ECU (not shown) of the cell capacity thus calculated via the communication unit 10d, and the ECU refers to the cell capacity to adjust the voltage generated by the alternator 16. , control is performed so that the lead-acid battery 14 is fully charged or nearly so.

As a result, even if the progress of deterioration differs among the cells due to the difference in temperature between the cells of the lead-acid battery 14, the state of the cells can be known, and variations between the cells can be taken into consideration. Thus, the charge/discharge control of the lead-acid battery 14 can be performed. As a result, it is possible to prevent the capacity of the lead-acid battery 14 from decreasing and the engine 17 to be unable to start. In addition, it is possible to suppress the progress of deterioration due to the state in which the capacity of the lead-acid battery 14 continues to be low.

Next, an example of processing executed in the embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG.

FIG. 7 is a flowchart executed when the engine 17 is started. When the process of the flowchart shown in FIG. 7 is started, the following steps are executed.

In step S10, for example, the CPU 10a determines whether or not the ignition key is operated by the user to start the engine 17. If it is determined that the engine 17 has been started (step S10: Y), the process proceeds to step S11. , otherwise (step S10: N), the process is terminated.

In step S11, the CPU 10a receives the temperature signal output from the temperature sensor 13-1 via the I/F 10e and acquires the temperature θ1. For example, the temperature θ1 of the cell 141 is acquired from the temperature sensor 13-1 shown in FIG.

At step S12, the CPU 10a receives the temperature signal output from the temperature sensor 13-2 via the I/F 10e and obtains the temperature θ2. For example, the temperature θ2 of the cell 146 is obtained from the temperature sensor 13-2 shown in FIG.

In step S13, the CPU 10a obtains the product (θ1×ΔT) of the temperature θ1 obtained in step S11 and the temperature sampling period ΔT, and cumulatively adds it to the variable C1 (calculates C1←C1+θ1×ΔT). As a result, values corresponding to time integration of the temperature θ1 are sequentially stored in the variable C1.

In step S14, the CPU 10a obtains the product (θ2×ΔT) of the temperature θ2 obtained in step S12 and the temperature sampling period ΔT, and cumulatively adds it to the variable C2 (calculates C2←C2+θ2×ΔT). As a result, values corresponding to the time integration of the temperature θ2 are sequentially stored in the variable C2.

In step S15, the CPU 10a stores the values of C1 and C2 obtained in steps S13 and S14 in the RAM 10c as data 10ca.

In step S16, the CPU 10a determines whether or not the sampling time ΔT has elapsed. If it is determined that ΔT has elapsed (step S16: Y), the process proceeds to step S17; otherwise (step S16 :N), the same process is repeated.

In step S17, the CPU 10a, for example, determines whether or not the ignition key is operated by the user to stop the engine 17. If it is determined that the engine 17 has been stopped (step S17: Y), the process ends. Otherwise (step S17: N), the process returns to step S11 to repeat the same processing as in the above case. Note that the process is not terminated when the engine 17 is stopped, but when the temperature of the engine 17 becomes equal to the ambient temperature, or when the difference from the ambient temperature becomes equal to or less than a predetermined threshold. It may be terminated.

Next, with reference to FIG. 8, an example of processing executed after the engine is stopped will be described. When the process of the flowchart shown in FIG. 8 is started, the following steps are executed.

In step S30, for example, the CPU 10a determines whether or not the ignition key is operated by the user to stop the engine 17. If it is determined that the engine 17 has been stopped (step S30: Y), the process proceeds to step S31. , otherwise (step S30: N), the process ends.

In step S31, the CPU 10a determines whether a predetermined time (for example, several hours until the stratification of the lead-acid battery 14 is eliminated) has passed since the engine 17 was stopped, and the predetermined time has passed. If so (step S31: Y), the process proceeds to step S32, otherwise (step S31: N), the same process is repeated.

In step S32, the CPU 10a supplies a control signal to the discharge circuit 15 to start pulse discharge of the lead-acid battery 14. FIG. Instead of discharging by the discharge circuit 15, for example, discharge by the starter motor 18 or the load 19 may be used.

In step S<b>33 , the CPU 10 a receives a voltage signal from the voltage sensor 11 and detects the terminal voltage V of the lead-acid battery 14 .

In step S34, the CPU 10a receives a current signal from the current sensor 12 and detects the current I flowing through the lead-acid battery 14. FIG.

In step S35, the CPU 10a determines whether or not a predetermined time (for example, 100 milliseconds to several seconds) has passed. If it is determined that the predetermined time has passed (step S35: Y), the process proceeds to step S36. Otherwise (step S35: N), the process returns to step S33 and repeats the same process. By repeating steps S33 to S35, the lead-acid battery 14 is repeatedly pulse-discharged, and the voltage and current at that time are measured.

In step S36, the CPU 10a supplies a control signal to the discharge circuit 15 to terminate the pulse discharge of the lead-acid battery 14. FIG.

In step S37, the CPU 10a, for example, calculates the values of the elements forming the equivalent circuit of the lead-acid battery 14 shown in FIG. For example, the CPU 10a obtains the equivalent circuit of the lead-acid battery 14 shown in FIG. 4 by learning processing or fitting processing, calculates the values of the elements of the equivalent circuit, and performs optimization. As an optimization method, for example, as described in Japanese Patent No. 4532416, an optimum state vector X is estimated by an extended Kalman filter operation, and an adjustment parameter (component) of an equivalent circuit is obtained from the estimated state vector X. Update to best fit. More specifically, based on an equivalent circuit using adjustment parameters obtained from the state vector X in a certain state, the voltage drop ΔV when the secondary battery is discharged with a predetermined current pattern is calculated, and this approaches the measured value. Update the state vector X as follows. Then, the optimum adjustment parameter is calculated from the state vector X optimized by updating. Alternatively, as described in WO2014/136593, when the lead-acid battery 14 is pulse-discharged, the temporal change in voltage value is obtained, and the obtained change in voltage value is fitted by a predetermined function with time as a variable. Thus, the parameters of the predetermined function can be calculated, and the components of the equivalent circuit of the lead-acid battery 14 can be obtained based on the calculated parameters of the predetermined function. Of course, methods other than these may be used.

At step S38, the CPU 10a reads the values of C1 and C2 stored in the RAM 10c by the process shown in FIG.

In step S39, the CPU 10a executes processing for correcting the internal resistance of each cell based on C1 and C2 read out in step S38. For example, the internal resistance value (6Y) as the total value of Rohm, Rct1, and Rct2 shown in FIG. .

In step S40, the CPU 10a calculates SOC and SOH based on the corrected internal resistance value of each cell. More specifically, the OCV of each cell can be calculated based on the internal resistance of each cell, and the SOC of each cell can be obtained from the OCV. Also, the SOH for each cell can be obtained by referring to a formula or table showing the relationship between the value of the internal resistance of each cell and the deterioration characteristic. Of course, SOC and SOH may be obtained by methods other than these. Note that an SOF (State of Function) indicating the starting performance of the engine 17 may be calculated based on the internal resistance.

In step S41, the CPU 10a executes control based on the SOC and SOH of each cell obtained in step S40. For example, by executing charge control based on the minimum SOC, the state of charge can be properly maintained. Further, by determining the deterioration state based on the minimum SOH, it is possible to accurately notify the user when it is time to replace the lead-acid battery 14 . Further, by executing charging control based on the minimum SOF, it is possible to prevent the engine 17 from being unable to be restarted. Note that step S41 is not executed by the CPU 10a, but rather the CPU 10a supplies the SOC and SOH for each cell obtained in step S40 to a higher control device (e.g., ECU), and the higher control device determines the SOC and SOH. Based on this, the above-described processing may be executed.

As described above, according to the embodiment of the present invention, the state of the lead-acid battery 14 can be accurately detected even when there is temperature variation among the cells 141 to 146 of the lead-acid battery 14. can be done. As a result, charging and discharging of the lead-acid battery 14 can be reliably controlled, so that the operation of the vehicle can be stabilized.

(C) Description of Modified Embodiment The above-described embodiment is merely an example, and needless to say, the present invention is not limited to the case described above. For example, in the above embodiment, as shown in FIG. 2, the two temperature sensors 13-1 and 13-2 are provided on the surfaces 14a and 14b of the electrolytic bath 140 of the lead-acid battery 14, respectively. As shown in FIG. 9, in addition to the two surfaces 14a and 14b, a surface 14c (front surface parallel to the YZ plane), a surface 14d (back surface parallel to the YZ plane), and a surface 14e (electrolytic Temperature sensors indicated by circles may be provided at six locations on the upper surface of the bath 140) and the surface 14f (bottom surface of the electrolytic bath 140). In this way, when six temperature sensors are used, the direction in which the heat source exists can be predicted by referring to the temperatures of the opposing surfaces, so the temperatures of the cells 141 to 146 can be estimated more accurately. can.

FIG. 10 is a diagram showing an example of heat distribution of the lead-acid battery 14 when heat sources exist in various directions. In addition, in FIG. 10, the lines drawn on the lead-acid battery 14 indicate contour lines of heat. Also, the thick line indicates the highest temperature contour line closest to the heat source. Here, FIG. 10A shows contour lines when the heat source exists in the vicinity of the vertex V1 of the electrolytic cell 140. FIG. Also, FIG. 10B shows a case where the heat source exists in the vicinity of side S1 parallel to the X-axis. Also, FIG. 10C shows a case where the heat source exists in the vicinity of side S2 parallel to the Y-axis. For example, by providing a plurality of sensors as shown in FIG. 9, the temperatures of the cells 141 to 146 can be more accurately estimated even when heat sources exist at various positions as shown in FIG. .

FIG. 11 shows an embodiment in which a temperature sensor is provided for each of the cells 141-146. In the example of FIG. 11, a temperature sensor indicated by a circle is provided near the center in the Y-axis direction and near the center in the Z-axis direction of each of the cells 141 to 146 on the surface 14c. According to such an embodiment, since the temperature of each cell can be detected, compared with the case of estimating the temperature of the intermediate cells 142 to 145 from the temperatures of the cells 141 and 146 at both ends, can be accurately determined.

In the example of FIG. 11, when the values obtained by time-integrating the temperatures of the cells 141 to 146 are C1 to C6, the above-described formulas (1) to (6) can be converted into, for example, the following formulas ( 7) to formula (12) can be substituted. Note that f11() to f16() are f11() to f16()=1/6 when C1=C2=C3=C4=C5=C6. It is a function whose value varies (eg, if C1 is relatively greater than C2-C6, then the value of f11() is relatively greater than the values of f12()-f16()).

R1=6Y×f11 (C1, C2, C3, C4, C5, C6) (7)
R2=6Y×f12 (C1, C2, C3, C4, C5, C6) (8)
R3=6Y×f13(C1, C2, C3, C4, C5, C6) (9)
R4=6Y×f14 (C1, C2, C3, C4, C5, C6) (10)
R5=6Y×f15 (C1, C2, C3, C4, C5, C6) (11)
R6=6Y×f16 (C1, C2, C3, C4, C5, C6) (12)

In the above embodiment, the case where the temperature of the cell rises due to the heat from the heat source existing outside the lead-acid battery 14 has been described as an example. may rise. More specifically, there are two types of heat generated by the lead-acid battery 14 . One is Joule heat generated by passing an electric current through internal resistance, and the other is heat generated by an electrochemical reaction. Here, since the internal resistance of the cell increases as deterioration progresses, the more deteriorated the cell, the more Joule heat is generated.

When the temperature of the cells rises due to heat from an external heat source, the heat is transferred from the cells closer to the heat source and the temperature rises, so the temperature of the end cells closer to the heat source is generally the highest. However, in the case of heat generated from the lead-acid battery 14 itself, particularly Joule heat, the amount of heat generated varies depending on deterioration, so the temperature of cells other than the end portions may be the highest.

The embodiment shown in FIG. 2 is a model in which heat is transferred from an external heat source to one of the cells at both ends, and the heat is transferred to the other cell at both ends. Therefore, when the heat generation of the middle cell is relatively larger than that of the other cells, it becomes difficult to accurately obtain the temperature of each cell.

On the other hand, in the case of the embodiment shown in FIG. 11, the temperature of each cell can be accurately measured even when the cells generate heat. For example, even if the deterioration of the cell 143, which is the intermediate cell, progresses and the heat generation amount of the cell 143 is the largest, the temperature of the cell 143 is required to be high, and the other cells 141 to 142, 144 to The temperature of 146 can also be determined accurately. In the example shown in FIG. 11, the temperature sensor is provided only for the surface 14c, but the surface 14d, which is the rear surface, is also provided with a temperature sensor for each cell in the same manner as for the surface 14c. may According to such a configuration, the temperature of each cell is obtained by two temperature sensors, and the average value of the obtained temperatures is obtained, whereby the temperature of the cell can be detected more accurately.

FIG. 12 shows an embodiment with more temperature sensors. In the example of FIG. 12, three temperature sensors are juxtaposed in the Z-axis direction for each cell on surfaces 14c and 14d. Also, three sensors are arranged in the X-axis direction and three sensors are arranged in the Z-axis direction with respect to the surfaces 14a and 14b.

By arranging a large number of temperature sensors in this way, for example, it is possible to accurately detect the temperature distribution as shown in FIG. In addition, stratification can be detected by arranging a plurality of temperature sensors in the vertical direction (Z-axis direction). That is, when stratification occurs, a high-concentration electrolytic solution (sulfuric acid) is accumulated in the lower part in the Z-axis direction, so that the amount of chemical reaction heat generated in this portion is relatively large. Therefore, the state of stratification can be detected by detecting and comparing the temperatures in the vertical direction. By correcting the internal resistance value of each cell (the values of R1 to R6 obtained by formulas (7) to (12)) in consideration of the stratification state, a more accurate internal resistance value can be obtained. can be obtained.

Although temperature sensors are provided on all of the surfaces 14a, 14b, 14c, and 14d in FIG. 12, they may be provided on only one of the opposing surfaces 14a, 14b and 14c, 14d. Also, it may not be provided on the surfaces 14a and 14b. Also, one cell may be provided with one temperature sensor only at the bottom (a portion where the influence of stratification tends to appear).

FIG. 13 shows another embodiment. In the example shown in FIG. 13, one temperature sensor is arranged in the center of the surfaces 14c and 14b, and four temperature sensors are arranged near the four corners of the surfaces.

In the embodiment shown in FIG. 13, two temperature sensors are arranged in each of the cells 141 and 146 on the surface 14c in the vertical direction, and five temperature sensors are arranged on each of the surfaces 14a and 14b. can accurately detect the temperature of the cells 141, 146 at both ends which are susceptible to the influence of . In addition, by arranging two temperature sensors in the vertical direction of the cells 141 and 146 at both ends and arranging two temperature sensors vertically on each of the surfaces 14a and 14b, stratification can be accurately detected. can. Furthermore, since a temperature sensor is arranged near the center of the surface 14c, it is possible to detect the temperature of the intermediate cells 143 and 144 and to know whether there is any influence other than an external heat source.

FIG. 14 shows another embodiment. In the example of FIG. 14, a temperature sensor is arranged inside a cover 20 that houses the lead-acid battery 14 (for example, a cover that protects the lead-acid battery 14 from high/low temperatures). More specifically, in the example of FIG. 14, six temperature sensors are arranged inside the cover 20 so as to correspond to the positions of the cells 141-146. Three temperature sensors are arranged at positions corresponding to the surface 14 a of the lead-acid battery 14 . By providing the temperature sensor inside the cover 20 in this way, it is possible to suppress the transfer of heat from the heat source and detect the state of each cell. In the example of FIG. 14, six temperature sensors are provided on the surface in contact with the surface 14c, and three temperature sensors are provided on the surface in contact with the surface 14a. good too.

Although the equivalent circuit shown in FIG. 4 is used in the above embodiment, other equivalent circuits may be used. For example, Rct1, Cd1 and Rct2, Cd2 may be one equivalent circuit or three or more equivalent circuits. Alternatively, an equivalent circuit consisting of only the resistors Rohm, Rct1, and Rct2, or an equivalent circuit using these three resistors as one resistor may be used.

In the above embodiment, the internal resistance is obtained by referring to the time integral value of the cell temperature, but the electric double layer capacitances Cd1 and Cd2 shown in FIG. 4 may be obtained. Also, the temperatures detected by the temperature sensors 13-1 and 13-2 may simply be added rather than time-integrated.

Also, the flowcharts shown in FIGS. 7 and 8 are examples, and the present invention is not limited to the processing of these flowcharts.

1 lead-acid battery state detection device 10 control unit 10a CPU
10b ROM
10c RAM
10d communication unit 10e I/F
11 voltage sensor 12 current sensor 13-1, 13-2 temperature sensor 14 lead storage battery 15 discharge circuit 16 alternator 17 engine 18 starter motor 19 load

Claims (5)

In a lead-acid battery state detection device for detecting the state of an automotive lead-acid battery having an electrolytic bath divided into a plurality of cells,
a processor;
a memory that stores a program that implements the following functions when executed by the processor;
A voltage signal from a voltage sensor that detects the terminal voltage of the lead-acid battery, a current signal from a current sensor that detects the charge/discharge current of the lead-acid battery, and the temperatures of the cells located at both ends of the electrolytic cell are detected. receive temperature signals from two temperature sensors that
calculating values of elements constituting an equivalent circuit of the lead-acid battery based on the voltage signal and the current signal during discharge of the lead-acid battery;
The temperature indicated by the temperature signals received from the two temperature sensors is maintained until the engine of the vehicle in which the lead-acid battery is mounted is stopped, or until the temperature signals from the two temperature sensors become the same as the outside air temperature. Cumulative addition is performed for each temperature sensor , and when it is determined that there is a difference exceeding a predetermined threshold in the value obtained by the cumulative addition, the calculated values of the elements constituting the equivalent circuit for each of the cells are calculated. , correcting based on the following formula (1) using the value obtained by the cumulative addition, estimating the state of the lead-acid battery based on the corrected element value,
outputting the estimated state of the lead-acid battery;
A lead-acid battery state detection device characterized by:
Rk=n×Y×fk(C1, C2) Expression (1)
However, in the formula (1), k (1 ≤ k ≤ n) is an identification number indicating each cell in the electrolytic cell, and the cell located at one end of the electrolytic cell toward the other end of the electrolytic cell It is a natural number that increases by one. The cell located at one end of the cell has k equal to 1, and the cell located at the other end of the cell has k equal to n, where n equals the number of cells. Rk is the internal resistance of each cell, n.times.Y is the internal resistance of the entire cell, and fk(C1, C2) is a predetermined function of each cell with C1 and C2 as variables. C1 is a value obtained by cumulatively adding the temperature indicated by the temperature signal received from the temperature sensor that detects the temperature of the cell positioned at one end of the electrolytic cell among the two temperature sensors, and C2 is the value obtained by cumulative addition. It is a value obtained by cumulatively adding temperatures indicated by temperature signals received from one of the two temperature sensors that detects the temperature of the cell located at the other end of the electrolytic cell. f1 (C1, C2) to fn (C1, C2) are f1 (C1, C2)=...= fk(C1, C2)=...= fn(C1, C2)= when C1=C2. 1/n, f1(C1, C2)>..>fk(C1, C2)>..>fn(C1, C2) when C1>C2, and f1(C1 , C2)<..<fk(C1, C2)<..<fn(C1, C2). Among the corrected internal resistance values of the elements of each cell, the maximum value is selected, and the dischargeable capacity of each cell is estimated based on the selected internal resistance value. Item 2. The lead-acid battery state detection device according to item 1 . each of the two temperature sensors is spaced apart in the vertical direction of the electrolytic cell and configured as at least a pair of temperature sensors;
The temperature difference in the vertical direction of the electrolytic cell is detected based on the temperature indicated by the temperature signal, the degree of stratification of the electrolytic solution is detected based on the detected temperature difference, and the element is cooled based on the degree of stratification. 3. The lead-acid battery state detecting device according to claim 1, wherein the value is corrected. 4. The lead-acid battery state detection device according to claim 1 , wherein the temperature sensor is arranged in a cover that houses the lead-acid battery. In a lead-acid battery state detection method for detecting the state of an automotive lead-acid battery having an electrolytic cell partitioned into a plurality of cells,
A voltage signal from a voltage sensor that detects the terminal voltage of the lead-acid battery, a current signal from a current sensor that detects the charge/discharge current of the lead-acid battery, and the temperatures of the cells located at both ends of the electrolytic cell are detected. receiving, by a system having a processor, temperature signals from two temperature sensors that
calculating, by the system, values of elements constituting an equivalent circuit of the lead-acid battery based on the voltage signal and the current signal during discharging of the lead-acid battery;
The temperature indicated by the temperature signals received from the two temperature sensors is maintained until the engine of the vehicle in which the lead-acid battery is mounted is stopped, or until the temperature signals from the two temperature sensors become the same as the outside air temperature. Cumulative addition is performed for each temperature sensor , and when it is determined that there is a difference exceeding a predetermined threshold in the value obtained by the cumulative addition, the calculated values of the elements constituting the equivalent circuit for each of the cells are calculated. , correcting by the system based on the following formula (1) using the value obtained by the cumulative addition, estimating the state of the lead-acid battery by the system based on the corrected element value,
outputting by the system the estimated state of the lead-acid battery;
A lead-acid battery state detection method characterized by:
Rk=n×Y×fk(C1, C2) Expression (1)
However, in the formula (1), k (1 ≤ k ≤ n) is an identification number indicating each cell in the electrolytic cell, and the cell located at one end of the electrolytic cell toward the other end of the electrolytic cell It is a natural number that increases by one. The cell located at one end of the cell has k equal to 1, and the cell located at the other end of the cell has k equal to n, where n equals the number of cells. Rk is the internal resistance of each cell, n.times.Y is the internal resistance of the entire cell, and fk(C1, C2) is a predetermined function of each cell with C1 and C2 as variables. C1 is a value obtained by cumulatively adding the temperature indicated by the temperature signal received from the temperature sensor that detects the temperature of the cell positioned at one end of the electrolytic cell among the two temperature sensors, and C2 is the value obtained by cumulative addition. It is a value obtained by cumulatively adding temperatures indicated by temperature signals received from one of the two temperature sensors that detects the temperature of the cell located at the other end of the electrolytic cell. f1 (C1, C2) to fn (C1, C2) are f1 (C1, C2)=...= fk(C1, C2)=...= fn(C1, C2)= when C1=C2. 1/n, f1(C1, C2)>..>fk(C1, C2)>..>fn(C1, C2) when C1>C2, and f1(C1 , C2)<..<fk(C1, C2)<..<fn(C1, C2).

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