WO2018139299A1 - Inverter control device - Google Patents

Abstract

This inverter control device controls an inverter for converting power between a power source and an MG. The voltage feedback control unit (601) of the inverter control device calculates a torque command (Tm*) for the powering or regenerating torque of the MG according to a voltage deviation (ΔV), which is the difference between a target capacitor voltage (Vtgt) and a capacitor voltage detection value (Vsns), when the power supply relay provided in the power path between the power source and the inverter is interrupted. The correction unit (671) of the voltage feedback control unit (601) calculates, on the basis of the MG rotational speed (Nm,) a correction factor (α) that approaches 0 the higher the MG rotational speed (Nm) gets, and multiplies the proportional gain (Kp) and integral gain (Ki) of the voltage feedback control by the correction factor (α).

Description

Inverter control device Cross-reference of related applications

This application is based on Patent Application No. 2017-13988 filed on January 30, 2017, the contents of which are incorporated herein by reference.

This disclosure relates to an inverter control device.

Conventionally, in a system for driving a motor generator by converting the power of a main engine battery mounted on an electric vehicle with an inverter, a system is known in which a power relay is cut off when the main battery is abnormal and power is generated by regenerative torque of the motor generator. ing. During regenerative power generation, the inverter is voltage-controlled so that the capacitor voltage applied across the smoothing capacitor has a desired value.

For example, the vehicle battery control device disclosed in Patent Document 1 is provided with a low voltage side DCDC converter that steps down a high voltage and charges a low voltage battery for an auxiliary device on the main battery side of the inverter. When an abnormality of the main battery is detected, the power relay is cut off, and the low-voltage DCDC converter and the inverter are controlled according to the magnitude relationship between the voltage of the smoothing capacitor and the output voltage command value of the low-voltage DCDC converter.

Japanese Patent No. 5171578

In the prior art of Patent Document 1, when the capacitor voltage fluctuates due to fluctuations in power used by the auxiliary machine, the capacitor voltage fluctuation is suppressed by utilizing the characteristics of the bidirectional DCDC converter. However, this technique cannot be applied to a system that does not include a bidirectional DCDC converter. An attempt to use a bidirectional DCDC converter to apply this technique leads to an increase in cost.

In the prior art of Patent Document 1, when the high-voltage side capacitor voltage fluctuates, the output voltage command of the low-voltage side DCDC converter is increased to lower the capacitor voltage. However, in a system in which communication is performed between the inverter control unit and the DCDC converter control unit, there is a possibility that sufficient responsiveness cannot be ensured with respect to sudden fluctuation due to communication delay.

Therefore, it is desired to realize a control device capable of suppressing the capacitor voltage fluctuation by controlling the inverter alone, in contrast to the conventional technology having the problem of cost increase and communication delay due to the cooperation with the bidirectional DCDC converter.

An object of the present disclosure is to provide an inverter control device that stabilizes a voltage in an inverter control device that calculates a torque command by voltage control.

The inverter control device of the present disclosure mutually converts DC power on the power source side and AC power on the motor generator side, consumes power from the power source, causes the motor generator to output a power running torque, and regenerative torque of the motor generator The inverter that can supply the power generated by the power supply side is controlled. The inverter control device includes a voltage feedback control unit and a drive signal generation unit.

Here, the time when the power relay provided in the power path between the power source and the inverter is cut off is called “when the power is cut off”. The voltage across the capacitor provided on the power supply side of the inverter is referred to as “capacitor voltage”. The voltage feedback control unit calculates a torque command related to the power running torque or the regenerative torque of the motor generator according to a voltage deviation that is a difference between the target voltage and the detected value for the capacitor voltage when the power is shut off.

The drive signal generation unit generates a drive signal for switching the inverter based on the torque command calculated by the voltage feedback control unit when the power is shut off. Typically, when a power supply abnormality occurs, the power supply relay is cut off. The control in which the drive signal generator generates the drive signal based on the torque command calculated by the voltage feedback controller when the power is shut off is referred to as “voltage control”.

The voltage feedback control unit calculates a correction magnification that approaches 0 as the MG rotation speed increases, based on the MG rotation speed that is the rotation speed of the motor generator, and “any calculation amount in the calculation process of the voltage feedback control” ”Is multiplied by a correction magnification. Specifically, the correction unit multiplies the gain of voltage feedback control or the voltage deviation by a correction magnification as “any amount of calculation in the calculation process of voltage feedback control”.

In the voltage feedback control using the torque command as the operation amount, the power sensitivity differs depending on the MG rotation speed, and the power sensitivity increases as the rotation speed increases. For this reason, it is difficult to stabilize the capacitor voltage over the entire range of the MG rotation speed. On the other hand, in the present disclosure, at the time of executing the voltage control, the correction magnification calculated according to the MG rotation speed is multiplied by one of the calculation amounts in the calculation process of the voltage feedback control. The response characteristics can be made uniform. Therefore, the capacitor voltage can be stabilized.

The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is an overall configuration diagram of a vehicle control system to which an MG-ECU (inverter control device) of each embodiment is applied. FIG. 2 is a configuration diagram of the inverter and MG-ECU in the system of FIG. FIG. 3 is a diagram for explaining the response of the capacitor voltage when the auxiliary load power suddenly changes in the comparative example (general voltage control). FIG. 4 is a control block diagram of the voltage feedback control unit of the first embodiment. FIG. 5A is a diagram illustrating the relationship between the MG rotation speed and the correction magnification according to an inversely proportional curve. FIG. 5B is a diagram illustrating a relationship between the MG rotation speed and the correction magnification according to the linear interpolation map; FIG. 6 is a diagram for explaining the effect of voltage stabilization according to the present embodiment. FIG. 7 is a main flowchart showing the entire process when the main battery is abnormal. FIG. 8 is a sub-flowchart of the voltage control process. FIG. 9 is a control block diagram of the voltage feedback control unit of the second embodiment.

Hereinafter, a plurality of embodiments of the inverter control device will be described with reference to the drawings. The first and second embodiments differ only in the configuration of the correction unit of the voltage feedback control unit, and other configurations and operational effects are common. In this specification, the first and second embodiments are collectively referred to as “this embodiment”. The inverter control device of the present embodiment is applied to a hybrid vehicle including an engine and a motor generator (hereinafter “MG”) as a power source of the vehicle.

[Configuration of vehicle control system]
First, the overall configuration of a vehicle control system to which the MG-ECU 54 as an “inverter control device” in each embodiment is applied will be described with reference to FIG. The vehicle control system 10 applied to the vehicle 90 includes an engine 70, an MG 80, a main engine battery 20, an inverter 40, power transmission clutches 91 and 92, a transmission 93, a vehicle control device 50, and the like. The engine 70 converts thermal energy generated by burning fuel into rotational driving force.

The MG 80 consumes power supplied from the main battery 20 via the inverter 40 and generates power running torque as the main engine of the hybrid vehicle. The MG 80 is rotated by torque transmitted from the engine 70 or the drive shaft 94 side, and regenerates the generated power to the main battery 20 via the inverter 40. The MG 80 of this embodiment is a permanent magnet type synchronous three-phase AC motor generator. The rotation angle sensor 85 detects the rotation angle θ of the MG 80. In this embodiment, it is assumed that a resolver is used as the rotation angle sensor 85, but other rotation angle sensors may be used.

The main battery 20 as a “power source” is constituted by a chargeable / dischargeable secondary battery such as a nickel metal hydride battery or a lithium ion battery. As shown in FIG. 2, the positive electrode of the main battery 20 is connected to the high potential line P, and the negative electrode of the main battery 20 is connected to the low potential line N. The main battery 20 may be referred to as a “high voltage battery”, and an auxiliary battery 32 described later may be referred to as a “low voltage battery”. Further, a power storage device such as an electric double layer capacitor may be used as a power source instead of the battery.

Between the main battery 20 and the inverter 40, a power supply relay 21 capable of interrupting the power path is provided. The power supply relay 21 corresponds to a so-called system main relay, and includes a high potential side relay 22 provided on the high potential line P and a low potential side relay 23 provided on the low potential line N. The high potential side relay 22 and the low potential side relay 23 may be either a mechanical relay or a semiconductor relay.

The inverter 40 mutually converts the DC power on the main battery 20 side and the three-phase AC power on the MG 80 side. The inverter 40 can supply the power of the main battery 20 to the MG 80 to output the power running torque, and can supply the power generated by the regenerative torque of the MG 80 to the main battery 20 side.

As shown in FIG. 2, the inverter 40 is constituted by switching elements 41-46 of three-phase upper and lower arms. Specifically, switching elements 41, 42, and 43 are U-arm, V-phase, and W-phase upper arm switching elements, respectively, and switching elements 44, 45, and 46 are respectively under the U-phase, V-phase, and W-phase. This is an arm switching element. The switching elements 41 to 46 of the present embodiment are IGBTs (insulated gate bipolar transistors). Further, the switching elements 41 to 46 are accompanied by flywheel diodes that allow energization from the low potential emitter side to the high potential collector side. A capacitor 25 for smoothing the input voltage is provided on the main battery 20 side of the inverter 40. A voltage across the capacitor 25, that is, a potential difference between the high potential line P and the low potential line N is referred to as a capacitor voltage Vc. The voltage sensor 24 detects the capacitor voltage Vc.

A DCDC converter 30 as an “auxiliary power conversion circuit” is connected to a path branched from the power path between the power supply relay 21 and the inverter 40. The DCDC converter 30 can bidirectionally convert the high voltage on the main battery 20 and inverter 40 side and the low voltage on the auxiliary battery 32 side. The auxiliary battery 32 composed of a secondary battery such as a lead storage battery is charged by the output voltage of the DCDC converter 30 and supplies low-voltage power to various auxiliary loads 33 of the vehicle. The auxiliary machine load 33 includes a starter, an electric power steering device, a brake actuator, and the like that have functions necessary for retreat travel.

The engine side clutch 91 is provided on the output shaft 71 of the engine 70 and intermittently transmits power between the engine 70 and the MG 80. The transmission side clutch 92 is provided on the output side of the MG 80, and interrupts power transmission between the MG 80 and the transmission 93. The transmission 93 can change the power transmitted to the drive shaft 94. The driving force transmitted to the drive shaft 94 on the output side of the transmission 93 is transmitted to the axle 96 through the differential gear 95 to rotate the drive wheels 98.

As shown in FIG. 2, the vehicle control device 50 includes a plurality of individual ECUs such as a battery ECU 52 and an MG-ECU 54, and a general ECU 51 that controls them, and comprehensively performs various controls related to driving of the vehicle. . As for information communication between the engine 70, the transmission 93, and the vehicle control device 50, only communication is indicated by broken lines in FIG. 1, and the engine ECU and transmission ECU, which are other individual ECUs, are not shown in FIG. To do. Each ECU is composed mainly of a microcomputer or the like, and can transmit and receive information via a communication network such as CAN. The processing in each ECU may be software processing by a CPU executing a program stored in advance in a substantial memory device such as a ROM, or may be hardware processing by a dedicated electronic circuit.

The overall ECU 51 acquires information from the individual ECUs such as the battery ECU 52 and the MG-ECU 54, and also acquires information on the accelerator opening, the shift position, the vehicle speed, and the like from an unillustrated accelerator sensor, shift switch, vehicle speed sensor, and the like. Based on the acquired information, the overall ECU 51 controls the entire vehicle 90 and transmits a command signal to each individual ECU. In particular, in the present embodiment, the overall ECU 51 has a function of transmitting a voltage control command to the MG-ECU 54 when the power is shut off.

The battery ECU 52 acquires main unit battery information such as voltage, current, temperature, and SOC of the main unit battery 20 and monitors the state of the main unit battery 20 so that the SOC of the main unit battery 20 is within a predetermined range. Further, the battery ECU 52 detects an abnormality of the main unit battery 20 based on the acquired main unit battery information. The abnormality of the main battery 20 includes a voltage abnormality in which the voltage deviates from the normal range, an overcurrent abnormality in which the current exceeds the upper limit value, and an SOC abnormality in which the SOC deviates from the normal range. When abnormality of main unit battery 20 is detected, battery ECU 52 cuts off power supply relay 21 and disconnects main unit battery 20 from inverter 40 and MG 80.

When the power relay 21 is cut off, the MG 80 stops the power running operation, and the hybrid vehicle basically retreats with the power of the engine 70. Along with this, the MG 80 is rotated by the torque transmitted from the engine 70 or the drive shaft 94 side to generate electric power. The electric power generated by MG 80 is applied to inverter 40. When electric power is consumed by using the auxiliary machine load 33 such as a starter or an electric power steering device during the evacuation traveling, the DCDC converter 30 operates to charge the auxiliary battery 32 by reducing the capacitor voltage Vc. Since the power is appropriately consumed by the auxiliary load 33, the capacitor voltage Vc is prevented from being overvoltage. Even if the power supply from main unit battery 20 is cut off, the regenerative power of MG 80 can be used to continue using auxiliary load 33 during the evacuation travel.

Hereinafter, the time when the power supply relay 21 is connected and power is supplied from the main battery 20 to the inverter 40 is referred to as “normal time”. The time when the power supply relay 21 is cut off and the power supply from the main battery 20 to the inverter 40 is stopped is referred to as “when power is cut off”. In the present embodiment, it is assumed that the time when the abnormality of the main battery 20 is detected is mainly when the power is shut off. However, the case where the power relay 21 becomes unable to be connected due to a failure of the power relay 21 itself or a communication abnormality to the power relay 21 is also included when the power is shut off. Further, although the inverter 40 is actually normal, it may be erroneously determined to be abnormal due to noise or the like, and the power supply relay 21 may be temporarily cut off. In this case, this embodiment can be applied to inverter control until the power relay 21 is connected again.

During normal operation, the MG-ECU 54 generates a drive signal for switching the inverter 40 based on the torque command Tm ^* received from the overall ECU 51. This inverter drive control is called “torque control”. On the other hand, when the power is shut off, a voltage control command is transmitted from the overall ECU 51 to the MG-ECU 54. When the voltage control command is received and the voltage control execution condition described later is satisfied, the MG-ECU 54 generates a drive signal based on the torque command Tm ^* generated by the internal voltage feedback control unit 60. This inverter drive control is called “voltage control”. In addition, although illustration of signal lines and the like is omitted, the MG-ECU 54 notifies the overall ECU 51 of information such as the actual torque and the actual rotational speed of the MG 80.

[Configuration of MG-ECU]
The MG-ECU 54 of this embodiment includes a current command calculation unit 55, a current feedback control unit 56, and a voltage feedback control unit 60. The current command calculation unit 55 and the current feedback control unit 56 constitute a “drive signal generation unit that generates a drive signal based on the torque command Tm ^* ”. In the current feedback control, a well-known vector control is used. Based on the torque command Tm ^* , the current command calculation unit 55 calculates the dq axis current commands Id ^* and Iq ^* using a map and a mathematical expression. As described above, the torque command Tm ^* is input from the overall ECU 51 in the normal torque control, and is input from the voltage feedback control unit 60 in the voltage control when the power is shut off.

The current feedback control unit 56 acquires the phase current detected by the current sensor 84 and the rotation angle θ detected by the rotation angle sensor 85. FIG. 2 shows an example of detecting the phase currents Iv and Iw of the V-phase and W-phase, and calculating the remaining U-phase current Iu according to Kirchhoff's law as an example of detecting the phase current. . However, any two-phase current may be detected, and a three-phase current may be detected. The current feedback control unit 56 dq-converts the phase current using the rotation angle θ and feeds back to the dq axis current commands Id ^* and Iq ^* . Then, the voltage command is calculated by PI control or the like so that the detected current value follows the current command, and a drive signal is generated by PWM modulation or the like. Since current feedback control is a well-known technique, detailed description thereof is omitted.

The voltage control execution condition is satisfied when the MG rotation speed Nm and the capacitor voltage Vc are within the respective upper and lower limit values. That is, when the upper limit value of the MG rotation speed Nm is expressed as NmH, the lower limit value is expressed as NmL, the upper limit value of the capacitor voltage Vc is expressed as VcH, and the lower limit value is expressed as VcL, the voltage control execution condition is expressed by the equations (1) and (2). It is represented by
NmL ≦ Nm ≦ NmH (1)
VcL ≦ Vc ≦ VcH (2)

When a voltage control command is received from the overall ECU 51 and the voltage control execution condition is satisfied, the MG-ECU 54 generates a drive signal by voltage control and causes the inverter 40 to perform a switching operation. At this time, the voltage feedback control unit 60 calculates the torque command Tm ^* by voltage feedback control that causes the detected value of the capacitor voltage Vc to follow the target voltage. On the other hand, when the voltage control execution condition is not satisfied, the MG-ECU 54 stops switching by shutting off all the switching elements 41-46. In the state where the gate is cut off, the current from the MG 80 side flows from the low potential side to the high potential side via the flywheel diode associated with the switching element 41-46. The above is the description of the basic configuration and operation of the MG-ECU 54.

Next, referring to FIG. 3, a problem in general voltage control will be described as a comparative example. FIG. 3 shows the response of the capacitor voltage Vc when the power consumption of the auxiliary load 33 is suddenly changed when the MG rotation speed Nm is 3000 rpm, 2000 rpm, or 1000 rpm. In the initial state before time t0, the capacitor voltage Vc maintains the target voltage Vtgt. When the auxiliary load power suddenly increases at time t0, electric power is supplied from the inverter 40 to the DCDC converter 30 in order to supplement the power consumption of the auxiliary battery 32. As a result, the capacitor voltage Vc temporarily decreases and then gradually returns toward the target voltage Vtgt. The amount of voltage decrease when the capacitor voltage Vc is minimized increases as the MG rotation speed Nm decreases, and increases as the MG rotation speed Nm increases. That is, the power sensitivity varies depending on the MG rotation speed Nm.

Further, a voltage lower limit value at which the DCDC converter 30 can ensure performance is defined as Vlim. In the example shown in FIG. 3, when the MG rotation speed Nm is 2000 rpm and 3000 rpm, the minimum value of the capacitor voltage Vc is not less than the voltage lower limit value Vlim. However, when the MG rotation speed Nm is 1000 rpm, the minimum value of the capacitor voltage Vc is lower than the voltage lower limit value Vlim. During the shortage period Psht where the capacitor voltage Vc falls below the voltage lower limit value Vlim, the DCDC converter 30 cannot operate normally, and power supply to the auxiliary battery 32 and the auxiliary load 33 may not be performed properly. . Therefore, in the voltage control of the comparative example, the capacitor voltage Vc becomes unstable due to the fluctuation of the MG rotation speed Nm.

Therefore, in this embodiment, in order to solve this problem, the configuration of the voltage feedback control unit 60 is improved with respect to general voltage control. Hereinafter, the detailed configuration and operational effects of the voltage feedback control unit 60 according to the present embodiment will be described separately for the first embodiment and the second embodiment. The code of the voltage feedback control unit of the first embodiment is “601”, and the code of the voltage feedback control unit of the second embodiment is “602”.

(First embodiment)
The configuration and operational effects of the voltage feedback control unit 601 of the first embodiment will be described with reference to FIGS. As shown in FIG. 4, the voltage feedback control unit 601 includes a deviation calculator 61, a proportional gain multiplier 62, an integral gain multiplier 63, an integrator 64, and an adder 65 as a general PI control configuration. . The deviation calculator 61 calculates a voltage deviation ΔV that is a difference between the target voltage Vtgt of the capacitor voltage Vc and the detected value Vsns. For example, the input voltage required for the DCDC converter 30 is set as the target voltage Vtgt.

The proportional gain multiplier 62 calculates a proportional term of the torque command Tm ^* by multiplying the voltage deviation ΔV by the proportional gain Kp. The integral gain multiplier 63 multiplies the voltage deviation ΔV by the integral gain Ki. The integrator 64 integrates the multiplication value to calculate the integral term of the torque command Tm ^* . The adder 65 adds the proportional term and the integral term, and outputs a torque command Tm ^* .

Thus, the voltage feedback control unit 601 calculates the torque command Tm ^* related to the power running torque or the regenerative torque of the MG 80 in accordance with the voltage deviation ΔV in the voltage control when the power is shut off. Here, it is assumed that the MG 80 mainly performs a regenerative operation when the power is shut off. However, when the power on the auxiliary battery 32 side of the DCDC converter 30 is excessive, power is supplied from the DCDC converter 30 to the inverter 40, and the MG 80 may perform a power running operation. Therefore, the torque command Tm ^* calculated by the voltage feedback control unit 601 relates to the “power running torque or regenerative torque” of the MG 80.

Moreover, the voltage feedback control unit 601 includes an MG rotation number calculation unit 66 and a correction unit 671 as a configuration unique to the present embodiment. The MG rotation speed calculation unit 66 converts the rotation angle θ detected by the rotation angle sensor 85 into the MG rotation speed Nm. Note that the MG rotation number calculation unit 66 is provided for other purposes in the current feedback control unit 56, for example, and the calculation result may be used by the voltage feedback control unit 601.

The correction unit 671 includes a magnification calculation unit 68 and magnification multipliers 692 and 693. Based on the MG rotation speed Nm, the magnification calculator 68 calculates a correction magnification α that approaches 0 as the MG rotation speed Nm increases. When the correction magnification α is defined as a positive value, the correction magnification α decreases as the MG rotation speed Nm increases. Hereinafter, description will be made assuming that the correction magnification α is a positive value. However, in other embodiments, the correction magnification may be defined as a negative value, and the calculation sign may be adjusted comprehensively.

Referring to FIG. 5A and FIG. 5B for details of the calculation of the correction magnification α. As shown in FIG. 5A, the correction magnification α is set to 1 when the MG rotation speed Nm is the reference rotation speed Nref, and is basically set to be inversely proportional to the MG rotation speed Nm. However, an upper limit guard is set to prevent the correction magnification α from becoming excessive in the low rotation region. That is, in the region below the guard rotation speed Ngrd, the correction magnification α is set to a constant guard value αgrd.

The magnification calculator 68 may calculate the product of the reciprocal of the MG rotation speed Nm and a constant using a mathematical formula. Further, the magnification calculator 68 stores a map of the MG rotation speed Nm and the correction magnification α shown in FIG. 5B in advance in the ROM area of the ECU, and may determine the correction magnification α by referring to this map. . In that case, the correction magnification α may be calculated by linear interpolation for the MG rotation speed Nm between the points defined in the map. Alternatively, the correction magnification α from a certain rotation speed to the next rotation speed on the map may be constant, and the correction magnification α may be set in a step shape.

That is, the correction magnification α may be set so as to have a negative correlation similar to the inverse proportion even if it is not strictly inversely proportional to the MG rotation speed Nm. In short, the correction magnification α may be set to approach 0 as at least the MG rotation speed Nm is high. By using a map with a small number of data, the processing load on the MG-ECU 54 can be reduced. On the other hand, the calculation accuracy can be improved in the mathematical calculation. The selection of mathematical formula or map reference and the number of map data to be used may be appropriately determined according to the balance between the processing capability of the ECU and the accuracy of the correction magnification α.

The magnification multiplier 692 multiplies the proportional gain Kp by the correction magnification α, and the magnification multiplier 693 multiplies the integral gain Ki by the correction magnification α. Then, the proportional term calculated using the corrected proportional gain αKp and the integral term calculated using the corrected integral gain αKi are added by the adder 65 and output as a torque command Tm ^* . Thus, in the first embodiment, the correction magnification α is multiplied by the proportional gain Kp and the integral gain Ki. In the configuration that performs PID control including differential control, the differential gain (Kd) may be similarly multiplied by the correction magnification α. In the first embodiment, these feedback gains correspond to “any calculation amount in the calculation process of voltage feedback control”.

Here, description will be made assuming that the correction magnification α is inversely proportional to the MG rotation speed Nm in the MG rotation speed region where the MG rotation speed Nm exceeds the guard rotation speed Ngrd. When the reference gain including each feedback gain at the reference rotational speed Nref is expressed as Kref, the corrected gain K (Nm) at the MG rotational speed Nm is expressed by Expression (3).
K (Nm) = Kref × (Nref / Nm) (3)

For example, if the reference rotation speed Nref is 3000 rpm and the guard rotation speed Ngrd is less than 1000 rpm, the corrected gain K (1000) at 1000 rpm is three times the reference gain Kref. The corrected gain K (2000) at 2000 rpm is 1.5 times the reference gain Kref.

As described above, in the first embodiment, in the voltage control, the torque command Tm ^* is calculated by the voltage feedback control using the feedback gain corrected in accordance with the MG rotation speed Nm. Then, inverter 40 is operated by a drive signal generated based on torque command Tm ^*, and capacitor voltage Vc generated by regenerative torque of MG 80 is controlled to a desired value.

FIG. 6 shows the response characteristics of the capacitor voltage Vc when the auxiliary load power suddenly changes in this embodiment, in contrast to FIG. 3 used for explaining the voltage control of the comparative example. According to the above example, it is assumed that the reference rotational speed Nref is 3000 rpm, the corrected gain at 1000 rpm is 3 times the reference gain Kref, and the corrected gain at 2000 rpm is 1.5 times the reference gain Kref. Then, the voltage response characteristics at 1000 rpm and 2000 rpm in FIG. 6 are smaller than the response characteristics in FIG.

As described above, in the first embodiment, the response characteristic of the capacitor voltage Vc at each rotation speed at the time of a sudden change in auxiliary machine load power is obtained by multiplying the feedback gain by the correction magnification α that is inversely proportional to the MG rotation speed Nm except for the guard region. In other words, the power sensitivity can be made uniform. Further, at 1000 rpm, in the present embodiment, the minimum value of the capacitor voltage Vc exceeds the voltage lower limit value Vlim, and the shortage period Psht does not occur, so that the DCDC converter 30 is normally operated immediately after the auxiliary load power sudden change. Can do.

Therefore, in the present embodiment, the capacitor voltage Vc at the time of sudden change in auxiliary load power is stabilized regardless of the MG rotation speed Nm. For example, when the vehicle is traveling on a rough road, a so-called slip grip phenomenon may occur in which the wheel contacts the road surface after idling, and the MG rotation speed Nm may change suddenly. Even in such a case, the capacitor voltage Vc can be stabilized in the first embodiment.

Next, processing when the main engine battery is abnormal will be described with reference to a main flowchart of FIG. 7 and a sub-flowchart of FIG. In the description of the flowchart, the symbol S represents “step”. During normal operation after S1 ready-on, the MG-ECU 54 generates a drive signal based on the torque command Tm ^* received from the general ECU 51 and torque-controls the inverter 40 in S2. The normal torque control is continued until the main battery abnormality is detected by the battery ECU 52 in S3.

When the battery ECU 52 detects an abnormality in the main engine battery, YES is determined in S3, and the power supply relay 21 is shut off in S4. Then, MG-ECU 54 stops switching of inverter 40 in S5. At this time, since the capacitor voltage Vc decreases, a diagnosis signal of the voltage sensor is generated in the normal torque control. However, in this process, since the power supply relay 21 is intentionally turned off and the switching of the inverter 40 is stopped, the diagnosis signal is unnecessary. Therefore, after the diagnosis signal is masked in S6, the MG-ECU 54 waits for reception of a voltage control command from the overall ECU 51. When MG-ECU 54 receives the voltage control command and determines YES in S7, the process proceeds to S8.

In S8, success or failure of the voltage control execution condition is determined by the above-described equations (1) and (2). If the voltage control execution condition is not satisfied and the answer is NO in S8, the process proceeds to S19. At the time of the first determination in S8, since the inverter switching has already been stopped in S5, the stopped state is maintained as it is in S19. When the voltage control execution condition is satisfied and the answer is YES in S8, the process proceeds to S10. In S10, inverter switching is started and voltage control is executed.

Refer to FIG. 8 for details of the voltage control process. Steps S11 to S15 are executed by the voltage feedback control unit 601. In S11, the MG rotation speed calculation unit 66 acquires the electrical angle θ detected by the rotation angle sensor 85, and calculates the MG rotation speed Nm. In S12, the magnification calculation unit 68 of the correction unit 671 calculates the correction magnification α using a mathematical formula or a map based on the MG rotation speed Nm. When the MG rotation speed Nm is equal to or less than the guard rotation speed Ngrd, the magnification calculator 68 sets the correction magnification α to the guard value αgrd and guards the upper limit in S13.

In S14, the multipliers 692 and 693 multiply the proportional gain Kp and the integral gain Ki by the correction magnification α. In S15, the voltage feedback control unit 601 calculates the torque command Tm ^* by PI control using the corrected proportional gain αKp and the corrected integral gain αKi. When PID control including differential control is performed, similarly, the corrected differential gain (αKd) is used.

The current command calculation unit 55 calculates current commands Id ^* and Iq ^* based on the torque command Tm ^* calculated by the voltage feedback control unit 601 in S16. In S17, the current feedback control unit 56 generates a drive signal to the inverter 40 by current feedback control that causes the actual current to follow the current commands Id ^* and Iq ^* .

Returning to FIG. 7, after the voltage control is executed, it is determined whether or not ready-off is performed in S20. When ready-off, YES is determined in S20 and the processing routine ends. If it is not ready-off and it is determined NO in S20, the process returns to before S8, and the success or failure of the voltage control execution condition is repeatedly determined. When the voltage control execution condition is not satisfied and the answer is NO in S8, the inverter switching is stopped in S19. After the inverter switching is stopped, unless it is ready-off in S20, the process returns to S8 again, and the success / failure determination of the voltage control execution condition is repeated.

The effect of this embodiment including the effect of 1st Embodiment or the following 2nd Embodiment is demonstrated.
(effect)
In the voltage feedback control using the torque command Tm ^* as the operation amount, the power sensitivity varies depending on the MG rotation speed Nm as shown in FIG. For this reason, the response characteristics are non-uniform and it is difficult to stabilize the capacitor voltage Vc in the entire region of the MG rotation speed Nm.

On the other hand, in the first embodiment, when voltage control is executed, the response characteristic is made uniform regardless of the MG rotational speed Nm by multiplying the feedback gain by the correction magnification α calculated according to the MG rotational speed Nm. can do. That is, while the operation amount is the torque command Tm ^* , an operation equivalent to operating the electric power can be realized. Therefore, the capacitor voltage Vc can be stabilized. Further, the capacitor 25 has a characteristic that the voltage change sensitivity with respect to the regenerative power from the MG 80 is higher as the voltage Vc is lower. By changing the feedback gain based on the detected value information of the current capacitor voltage Vc, the response can be made uniform with respect to any voltage, and the control can be easily stabilized.

Furthermore, in the prior art of Patent Document 1 (Japanese Patent No. 5171578), there are problems of cost increase by using a bidirectional DCDC converter and communication delay between the inverter control unit and the DCDC converter control unit. On the other hand, in the present embodiment, the fluctuation of the capacitor voltage Vc, particularly the overvoltage, can be suppressed by the single control of the inverter 40 by the MG-ECU 54.

Other well-known techniques in this technical field include a technique for preventing the occurrence of an inverter overvoltage by lowering a voltage command value in advance before a load change. However, when the load fluctuation cannot be predicted, overvoltage cannot be prevented. In addition, there is a known technique for increasing the feedback gain in order to catch a sign that the voltage has suddenly increased and suppress the voltage. However, it is necessary to create a high-response voltage detection circuit in order to catch a sign of a voltage surge, which complicates circuit design. This embodiment can also solve the problems in these well-known techniques.

Specifically, in the present embodiment applied to the MG drive system of the hybrid vehicle, it is assumed that the voltage control during the evacuation travel by the engine drive is performed in a situation where the power supply relay 21 is cut off when the main engine battery 20 is abnormal. The In this situation, the MG-ECU 54 of the present embodiment can stabilize the input voltage required for the DCDC converter 30 and ensure the function of the auxiliary load 33 such as the starter and the electric power steering device during the evacuation traveling.

(Second Embodiment)
A second embodiment will be described with reference to the control block diagram of FIG. In FIG. 9, the same reference numerals are given to substantially the same components as those in FIG. 4 of the first embodiment, and the description thereof will be omitted. In the voltage feedback control unit 602 of the second embodiment, the correction factor α is multiplied by the voltage deviation ΔV instead of the feedback gain of the first embodiment. That is, the voltage deviation ΔV corresponds to “any calculation amount in the calculation process of the voltage feedback control”.

The correction unit 672 of the voltage feedback control unit 602 includes a magnification calculation unit 68 and a magnification multiplier 691. The magnification multiplier 691 multiplies the voltage deviation ΔV by the correction magnification α, and outputs the obtained corrected voltage deviation αΔV to the proportional gain multiplier 62 and the integral gain multiplier 63. The voltage control processing according to the second embodiment only changes “feedback gain correction” in S14 in the flowchart of FIG. 8 to “voltage deviation correction”. In the second embodiment, the same effect as in the first embodiment can be obtained.

(Other embodiments)
(1) The circuit connected in parallel to the inverter 40 on the inverter 40 side of the power supply relay 21 is not limited to the DCDC converter 30 that steps down the capacitor voltage Vc and charges the auxiliary battery 32, and the power generated by the MG 80 in regenerative power generation. Any circuit can be used as long as it can be consumed for some purpose. For example, a high voltage system circuit that uses the capacitor voltage Vc as it is may be connected in parallel with the inverter 40.

(2) When the power relay 21 is cut off, the torque generation source that causes the MG 80 to perform a regenerative operation is not limited to the engine 70 of the hybrid vehicle. For example, even in an electric vehicle that does not include an engine, the present disclosure can be applied to a system in which the MG 80 can perform a regenerative operation by the rotational energy of a spare battery, a fuel cell, or a wheel when the vehicle goes down a hill. In addition, the present disclosure is not limited to an electric vehicle including one MG, and may be applied to an electric vehicle including two MGs connected by a power split mechanism, for example. Furthermore, the present disclosure is applicable not only to vehicles but also to MG drive systems for other uses.

(3) In the first embodiment, both the proportional gain Kp and the integral gain Ki are multiplied by the correction magnification α. However, in other embodiments, the proportional gain Kp, the integral gain Ki, or the differential gain (Kd) It is sufficient that at least one of them is multiplied by the correction magnification α. Further, for each feedback gain, the correction magnification formula or map may be changed.

(4) As a modification of the second embodiment in which the correction magnification α is multiplied by the voltage deviation ΔV, both the target voltage Vtgt and the detection value Vsns may be multiplied by the same correction magnification α. As described above, the target amount to be multiplied by the correction magnification α is “any amount of calculation in the calculation process of the voltage feedback control”, which can obtain the same effect as the case of multiplying the feedback gain Kp, Ki or the voltage deviation ΔV. If it is.

(5) The drive signal generation unit is not limited to the configuration configured by the current command calculation unit 55 and the current feedback control unit 56, and may be any unit that generates a drive signal based on the torque command Tm ^*. Control may be performed. In the present disclosure, any normal drive control method may be used, and the drive signal generation method may be changed between the normal time and the voltage control time.

As mentioned above, this indication is not limited to the above-mentioned embodiment at all, and can be implemented with various forms in the range which does not deviate from the meaning.

This disclosure has been described in accordance with the embodiment. However, the present disclosure is not limited to the embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent scope. In addition, various combinations and forms, and other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims (7)

DC power on the power source (20) side and AC power on the motor generator (80) side are mutually converted, power from the power source is supplied to the motor generator to output a power running torque, and regeneration of the motor generator is performed. An inverter control device for controlling an inverter (40) capable of supplying electric power generated by torque to the power source side,
When the power supply relay (21) provided in the power path between the power supply and the inverter is cut off, a capacitor voltage (a voltage across the capacitor (25) provided on the power supply side of the inverter is a capacitor voltage ( A voltage feedback control unit (601, 602) that calculates a torque command related to the power running torque or regenerative torque of the motor generator according to a voltage deviation that is a difference between the target voltage and the detected value for Vc);
A drive signal generator (55, 56) for generating a drive signal for switching the inverter based on a torque command calculated by the voltage feedback controller when the power is shut off;
With
The voltage feedback controller is
Based on the MG rotation speed (Nm) that is the rotation speed of the motor generator, the correction magnification (α) that approaches 0 is calculated as the MG rotation speed increases, and any calculation amount in the calculation process of voltage feedback control An inverter control device having a correction unit (671, 672) that multiplies the correction magnification by the correction magnification. Applied to a system in which an auxiliary power conversion circuit (30) is connected in parallel to the inverter on the inverter side of the power supply relay as a main generator that is a power source of an electric vehicle,
The inverter control device according to claim 1, wherein the voltage feedback control unit performs voltage feedback control using an input voltage required for the auxiliary machine power conversion circuit as the target voltage. The inverter control device according to claim 1 or 2, wherein the power relay is cut off when an abnormality occurs in the power source. The inverter control device according to any one of claims 1 to 3, wherein the correction unit determines the correction magnification with reference to a map of MG rotation speed and the correction magnification stored in advance. The inverter control device according to any one of claims 1 to 3, wherein the correction unit calculates the correction magnification that is inversely proportional to the MG rotation speed in an MG rotation speed region exceeding a predetermined guard rotation speed (Ngrd). The inverter control device according to any one of claims 1 to 5, wherein the correction unit (671) multiplies at least one of a proportional gain, an integral gain, and a differential gain of voltage feedback control by the correction magnification. . The inverter control device according to any one of claims 1 to 5, wherein the correction unit (672) multiplies the voltage deviation by the correction magnification.

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