Electric vehicle motor control system and electric vehicle

Abstract

This electric vehicle motor control system comprises: a battery; a motor having a rotor and a stator; two inverter circuits that are connected to the stator and each control the driving and regeneration of the motor; and a control device that controls the driving of the two inverter circuits. The control device drives each of the two inverter circuits and gives rotational torques in mutually opposite directions to the rotor, thereby causing the battery to discharge and performing a degradation diagnosis process for the battery on the basis of the output current or output voltage of the battery during discharge.

Description

Technical Field

[0001] The present disclosure relates to a motor control system for an electric vehicle and an electric vehicle.

Background Art

[0002] A battery mounted on an electric vehicle equipped with a drive motor as a drive source of the vehicle deteriorates as it is repeatedly used. When the battery deteriorates, for example, it becomes impossible to supply the necessary power to the drive motor during vehicle acceleration, or the cruising range of the vehicle becomes shorter due to a decrease in the maximum charge capacity of the battery. For this reason, various techniques for diagnosing battery deterioration have been proposed.

[0003] Here, a method of determining the degree of battery deterioration by measuring the internal impedance (internal resistance) of the battery is known. For example, Patent Document 1 discloses a technique for calculating the degree of battery deterioration using the increase rate of the internal resistance of the battery in a power storage system equipped with a battery.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in order to measure the internal impedance of the battery, it is necessary to charge and discharge the battery. In an electric vehicle, in order to charge and discharge the battery that supplies power to the motor, it is necessary to output driving torque from the motor or to regenerate the motor, and the timing for diagnosing the degree of deterioration of the battery is restricted during vehicle travel. Although it is conceivable to connect a discharging device to the system separately from the motor to discharge the battery, it is necessary to provide a load device for discharging in order to diagnose the degree of deterioration of the battery.

[0006] The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide an electric vehicle motor control system and an electric vehicle capable of increasing the degree of freedom in the execution timing of diagnosing the deterioration of a battery that supplies power to a motor without using a load device for discharging.

Means for Solving the Problems

[0007] In order to solve the above problems, according to an aspect of the present disclosure, there is provided an electric vehicle motor control system including a battery, a motor having a rotor and a stator, two inverter circuits connected to the stator for controlling driving and regeneration of the motor respectively, and a control device for controlling driving of the two inverter circuits, wherein the control device At least after starting the running of the electric vehicle, drives the two inverter circuits respectively to apply rotational torques in opposite directions to the rotor being and offset to discharge the battery, and executes a deterioration diagnosis process of the battery based on an output current or an output voltage of the battery during discharging. There is provided an electric vehicle motor control system and an electric vehicle including the motor control system. Additionally by without changing the output torque from the motor from the target output torque, Also, according to another aspect of the present disclosure, in a motor control system for an electric vehicle including a battery, a motor having a rotor and a stator, two inverter circuits connected to the stator for controlling driving and regeneration of the motor respectively, and a control device for controlling driving of the two inverter circuits, the control device drives the two inverter circuits respectively to apply rotational torques in opposite directions to the rotor to discharge the battery, and executes a deterioration diagnosis process of the battery based on the output current or output voltage of the battery during discharge, the motor control system for an electric vehicle, the control device predicts a state in which the target output torque of the motor remains constant for a predetermined time or more, during a period in which the target output torque remains constant for a predetermined time or more, discharges the battery by applying rotational torques in opposite directions to the rotor so that the output torque from the motor is maintained at the target output torque, and a motor control system for an electric vehicle that executes a deterioration diagnosis process of the battery is provided.

Advantages of the Invention

[0008] As described above, according to the present disclosure, the degree of freedom in the timing of executing the degradation diagnosis of the battery that supplies power to the motor can be increased without using a load device for discharging.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 4

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Figure 8

Embodiments for Carrying Out the Invention

[0010] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0011] <1. Configuration of Motor Control System for Electric Vehicle> First, an example of the configuration of a motor control system for an electric vehicle according to an embodiment of the present disclosure will be described.

[0012] FIG. 1 is a schematic diagram showing a configuration example of a vehicle (electric vehicle) 1 equipped with a motor control system 10 according to the present embodiment. As shown in the figure, the vehicle 1 is a four-wheel vehicle including a left front wheel 3LF, a right front wheel 3RF, a left rear wheel 3LR, and a right rear wheel 3RR (hereinafter, the left front wheel 3LF and the right front wheel 3RF may be collectively referred to as "front wheels 3F", and the left rear wheel 3LR and the right rear wheel 3RR may be collectively referred to as "rear wheels 3R"). The vehicle 1 is configured as a rear-wheel drive vehicle including a first motor 11L and a second motor 11R as driving power sources for generating the driving torque of the vehicle 1. The first motor 11L and the second motor 11R independently drive the left rear wheel and the right rear wheel, respectively.

[0013] The motor control system 10 includes a first motor 11L, a second motor 11R, a first inverter unit 13L, a second inverter unit 13R, a battery 20, a cooling water circuit 30, and a control device 50. As the first motor 11L and the second motor 11R, for example, a three-phase AC radial motor or an axial gap motor is used. However, the number of phases is not particularly limited. The first motor 11L outputs a driving torque transmitted to the left rear wheel 3LR via the left rear wheel drive shaft 5L. The second motor 11R outputs a driving torque transmitted to the right rear wheel 3RR via the right rear wheel drive shaft 5R.

[0014] Further, the first motor 11L and the second motor 11R have a function of performing regenerative power generation by receiving the rotational torque of the rear wheels 3R transmitted via the left rear wheel drive shaft 5L and the right rear wheel drive shaft 5R, respectively, when the vehicle 1 decelerates. The driving and regeneration of the first motor 11L and the second motor 11R are controlled by the control device 50. Rated output torques capable of continuously and stably outputting torque are defined for the first motor 11L and the second motor 11R, respectively.

[0015] The first motor 11L is provided with a first motor temperature sensor 15L. The second motor 11R is provided with a second motor temperature sensor 15R. The first motor temperature sensor 15L and the second motor temperature sensor 15R detect the temperature of the motor and transmit the detected temperature information to the control device 50, respectively.

[0016] The battery 20 is configured to include a plurality of battery cells which are rechargeable secondary batteries. The battery 20 may be, for example, a lithium-ion battery with a rated voltage of 200V, but the rated voltage and type of the battery 20 are not particularly limited.

[0017] The battery 20 is connected to the first motor 11L and the second motor 11R via the first inverter unit 13L and the second inverter unit 13R, and stores the electric power supplied to the first motor 11L and the second motor 11R. The battery 20 is provided with a battery management device 21 that detects the remaining capacity, output current, output voltage, battery temperature, etc. of the battery 20 and transmits them to the control device 50.

[0018] The first inverter unit 13L controls the driving and regeneration of the first motor 11L. In this embodiment, the first inverter unit 13L includes a first inverter circuit 13La and a second inverter circuit 13Lb, and controls the first motor 11L by the two inverter circuits 13La and 13Lb. The first inverter circuit 13La and the second inverter circuit 13Lb each convert the DC power swept from the battery 20 into three-phase AC power and supply it to the stator of the first motor 11L. Also, the first inverter circuit 13La and the second inverter circuit 13Lb each convert the three-phase AC power regenerated by the first motor 11L into DC power to charge the battery 20. The driving of the first inverter unit 13L is controlled by the control device 50.

[0019] The second inverter unit 13R controls the driving and regeneration of the second motor 11R. In this embodiment, the second inverter unit 13R includes a first inverter circuit 13Ra and a second inverter circuit 13Rb, and controls the second motor 11R by the two inverter circuits 13Ra and 13Rb. The first inverter circuit 13Ra and the second inverter circuit 13Rb each convert the DC power swept from the battery 20 into three-phase AC power and supply it to the stator of the second motor 11R. Also, the first inverter circuit 13Ra and the second inverter circuit 13Rb each convert the three-phase AC power regenerated by the second motor 11R into DC power to charge the battery 20. The driving of the second inverter unit 13R is controlled by the control device 50.

[0020] The control device 50 functions as a device that controls the driving of the first motor 11L and the second motor 11R by one or more processors executing a computer program. The computer program is a computer program for causing the processor to execute operations described later that the control device 50 should execute. The computer program executed by the processor may be recorded on a recording medium that functions as a storage unit (memory) 53 provided in the control device 50, or may be recorded on a recording medium built into the control device 50 or any recording medium externally attachable to the control device 50.

[0021] Examples of the recording medium for recording the computer program include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROM (Compact Disk Read Only Memory), DVD (Digital Versatile Disk), SSD (Solid State Drive), and Blu-ray (registered trademark); magneto-optical media such as floptical disks; storage elements such as RAM and ROM; flash memories such as USB (Universal Serial Bus) memories; and other media capable of storing programs.

[0022] Connected to the control device 50 are a first motor temperature sensor 15L, a second motor temperature sensor 15R, a battery management device 21, an ambient environment sensor 55, a vehicle state sensor 57, and a GNSS (Global Navigation Satellite System) sensor 59 via dedicated lines or communication means such as CAN (Controller Area Network) and LIN (Local Inter Net). Also connected to the control device 50 are a first inverter unit 13L and a second inverter unit 13R via dedicated lines or communication means such as CAN and LIN. The functional configuration of the control device 50 will be described in detail later.

[0023] The surrounding environment sensor 55 detects the surrounding environment of the vehicle 1. In the present embodiment, the surrounding environment sensor 55 is configured to be able to detect at least the road shape in front of the vehicle 1. In the present embodiment, the vehicle 1 includes front cameras 55LF and 55RF as the surrounding environment sensor 55.

[0024] The front cameras 55LF and 55RF capture the front of the vehicle 1 and generate image data. The front cameras 55LF and 55RF include image sensors such as CCD (Charged-Coupled Devices) or CMOS (Complementary Metal-Oxide-Semiconductor), and transmit the generated image data to the control device 50. In the vehicle 1 shown in FIG. 1, the front cameras 55LF and 55RF are configured as a stereo camera including a pair of left and right cameras, but may be a monocular camera. In addition to the front cameras 55LF and 55RF, the vehicle 1 may include one or more sensors such as a LiDAR (Light Detection And Ranging), a radar sensor such as a millimeter-wave radar, or an ultrasonic sensor.

[0025] The vehicle state sensor 57 consists of one or more sensors that detect the operation state and behavior of the vehicle 1. The vehicle state sensor 57 includes at least an accelerator position sensor that detects the accelerator opening and a vehicle speed sensor that detects the vehicle speed. In addition, the vehicle state sensor 57 may include, for example, a steering angle sensor, a brake stroke sensor, or a brake pressure sensor. Also, the vehicle state sensor 57 may include at least one of, for example, an acceleration sensor or an angular velocity sensor. The vehicle state sensor 57 transmits a sensor signal including the detected information to the control device 50.

[0026] The GNSS sensor 59 receives satellite signals transmitted from a plurality of satellites and detects the position of the GNSS sensor 59, that is, the position of the vehicle 1. The GNSS sensor 59 transmits the detected position information of the vehicle 1 to the control device 50.

[0027] <2. Configuration of the drive circuit of the motor> Next, the configuration of the drive circuit of the motor in the motor control system according to the present embodiment will be described.

[0028] FIG. 2 shows a circuit diagram of the drive circuits of the first motor 11L and the second motor 11R. The drive circuits of the first motor 11L and the second motor 11R have the same configuration. Therefore, in FIG. 2, the drive circuit of one motor is shown.

[0029] In the present embodiment, the first motor 11L has one rotor 41L and two sets of three-phase stator coils 43La, 43Lb. Similarly, the second motor 11R has one rotor 41R and two sets of three-phase stator coils 43Ra, 43Rb. When the motor is a single-stator type radial motor, two sets of three-phase stator coils insulated from each other are assembled for one stator. Also, when the motor is a double-stator type axial gap motor, three-phase stator coils are assembled for two stators arranged on both sides in the axial direction of the rotor, respectively.

[0030] The first inverter circuit 13La (13Ra) and the second inverter circuit 13Lb (13Rb) are each configured to include a plurality of switching elements. The driving of each switching element of the first inverter circuit 13La (13Ra) and the second inverter circuit 13Lb (13Rb) is controlled by the control device 50.

[0031] The first inverter circuit 13La (13Ra) is electrically connected to the first stator coil 43La (43Ra) of the first motor 11L (the second motor 11R). The first inverter circuit 13La (13Ra) includes three arm circuits 45u, 45v, 45w (hereinafter, simply referred to as the arm circuit 45 in general unless otherwise distinguished). The arm circuit 45u is electrically connected to the u-phase coil of the first stator coil 43La (43Ra) of the first motor 11L (the second motor 11R). The arm circuit 45v is electrically connected to the v-phase coil of the first stator coil 43La (43Ra) of the first motor 11L (the second motor 11R). The arm circuit 45w is electrically connected to the w-phase coil of the first stator coil 43La (43Ra) of the first motor 11L (the second motor 11R).

[0032] Each arm circuit 45 has an upper arm on the upstream side of the current and a lower arm on the downstream side of the current. The upper arm is electrically connected to the positive electrode side of the battery 20, and the lower arm is electrically connected to the negative electrode side of the battery 20. Switching elements 47u, 49u, 47v, 49v, 47w, 49w, in which diodes are electrically connected in antiparallel, are provided in the upper arm and the lower arm of each arm circuit 45, respectively. The switching elements 47u, 49u, 47v, 49v, 47w, 49w may be, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors), but other switching elements may also be used.

[0033] The first motor 11L (the second motor 11R) is driven by the first inverter circuit 13La (13Ra) and the second inverter circuit 13Lb (13Rb), and three-phase AC power is supplied to either one or both of the first stator coil 43La (43Ra) and the second stator coil 43Lb (43Rb), so that the rotor 41L (41R) is rotationally driven to output a driving torque. Further, the first motor 11L (the second motor 11R) supplies the regenerative power generated by either one or both of the first stator coil 43La (43Ra) and the second stator coil 43Lb (43Rb) to the battery 20 by the driving of the first inverter circuit 13La (13Ra) and the second inverter circuit 13Lb (13Rb).

[0034] Note that a converter circuit for boosting the voltage may be provided between the battery 20 and each inverter circuit.

[0035] <3. Control device> Subsequently, the configuration of the control device 50 will be described in detail. In the following description, the rotation of the first motor 11L and the second motor 11R in the forward direction of the vehicle 1 is referred to as "forward rotation", and the rotation of the first motor 11L and the second motor 11R in the reverse direction of the vehicle 1 is referred to as "reverse rotation".

[0036] FIG. 3 is a block diagram showing the functional configuration of the control device 50 of the motor control system 10 according to the present embodiment. The control device 50 includes a processing unit 51 and a storage unit 53. The processing unit 51 is configured to include one or more processors such as CPUs. Part or all of the processing unit 51 may be configured with updatable components such as firmware, or may be program modules executed according to instructions from a CPU or the like. The storage unit 53 is composed of a memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), or an SSD (Solid State Drive). However, the number and type of the storage unit 53 are not particularly limited. The storage unit 53 stores computer programs executed by the processing unit 51, various parameters used for arithmetic processing, detection data, arithmetic results, and other information.

[0037] The processing unit 51 of the control device 50 includes a target torque setting unit 61, a motor control unit 63, a surrounding environment detection unit 65, and a battery diagnosis processing unit 67. Each of these units may be a function realized by executing a computer program by a processor such as a CPU, or a part of them may be composed of an analog circuit. Hereinafter, after briefly explaining the functions of each unit of the processing unit 51, specific processing operations will be described.

[0038] (Target Torque Setting Unit) The target torque setting unit 61 sets the target torques of the first motor 11L and the second motor 11R. In the present embodiment, when performing the deterioration diagnosis process of the battery 20, the target torques of the first motor 11L and the second motor 11R are configured to be corrected by the battery diagnosis processing unit 67 described later.

[0039] Specifically, the target torque setting unit 61 sets the target output torques of the first motor 11L and the second motor 11R respectively based on the required driving torque of the vehicle 1. The required driving torque is calculated based on the operation amount of the accelerator pedal and the vehicle speed during manual driving. Also, the required driving torque is calculated based on the required acceleration obtained by arithmetic during automatic driving.

[0040] The target torque setting unit 61 basically sets the ratio of the target output torque of the first motor 11L to the target output torque of the second motor 11R to 5:5. On the other hand, when torque vectoring control for enhancing the turning performance of the vehicle 1 is executed, the target torque setting unit 61 relatively reduces the ratio of the target output torque of the motor in the turning direction of the vehicle 1. In this case, the target torque setting unit 61 determines the ratio of the target output torque of the first motor 11L to the target output torque of the second motor 11R based on, for example, the steering angle and the vehicle speed.

[0041] Further, the target torque setting unit 61 determines whether to drive the first motor 11L and the second motor 11R only by either the first stator coils 43La and 43Ra or the second stator coils 43Lb and 43Rb, respectively, or to drive both of them, according to the magnitudes of the target output torques of the first motor 11L and the second motor 11R, respectively. Thereby, the driving efficiency due to power loss caused by the operation of the switching elements, wiring resistance, etc. can be increased.

[0042] For example, when the target output torque is smaller than a predetermined threshold value, the target torque setting unit 61 determines to drive the first motor 11L and the second motor 11R only by either the first stator coils 43La and 43Ra or the second stator coils 43Lb and 43Rb, respectively. In this case, the target torque setting unit 61 sets the target output torques of the first motor 11L and the second motor 11R to the target output torque by either one of the first stator coils 43La and 43Ra or the second stator coils 43Lb and 43Rb, and sets the target output torque of the other stator coil to zero.

[0043] On the one hand, when the target output torque is equal to or greater than a predetermined threshold value, the target torque setting unit 61 determines to drive the first motor 11L and the second motor 11R by both the first stator coils 43La, 43Ra and the second stator coils 43Lb, 43Rb. In this case, the target torque setting unit 61 sets a value equal to half of the target output torque of each of the first motor 11L and the second motor 11R as the target output torque of each of the first stator coils 43La, 43Ra or the second stator coils 43Lb, 43Rb.

[0044] Note that the target torque setting unit 61 may always drive the first motor 11L and the second motor 11R by both the first stator coils 43La, 43Ra and the second stator coils 43Lb, 43Rb. In this case, the target torque setting unit 61 sets a value equal to half of the target output torque of each of the first motor 11L and the second motor 11R as the target output torque of each of the first stator coils 43La, 43Ra or the second stator coils 43Lb, 43Rb.

[0045] In addition, the target torque setting unit 61 sets the target regeneration torques of the first motor 11L and the second motor 11R based on the required braking torque of the vehicle 1. The required braking torque is calculated based on the operation amount of the accelerator pedal and the vehicle speed during manual driving. Also, the required driving torque is calculated based on the required acceleration obtained by calculation during automatic driving. The target torque setting unit 61 sets the ratio of the target regeneration torque of the first motor 11L to the target regeneration torque of the second motor 11R to 5:5.

[0046] In addition, the target torque setting unit 61 determines whether to regenerate the first motor 11L and the second motor 11R by only one of the first stator coils 43La, 43Ra or the second stator coils 43Lb, 43Rb, or by both, according to the magnitudes of the target regeneration torques of the first motor 11L and the second motor 11R respectively. Thereby, the regeneration efficiency due to power loss caused by the operation of the switching element, wiring resistance, etc. can be increased.

[0047] For example, when the target regeneration torque is less than a predetermined threshold value, the target torque setting unit 61 determines to regenerate the first motor 11L and the second motor 11R only by either the first stator coils 43La and 43Ra or the second stator coils 43Lb and 43Rb. In this case, the target torque setting unit 61 sets the target regeneration torque of each of the first motor 11L and the second motor 11R to the target regeneration torque by either the first stator coils 43La and 43Ra or the second stator coils 43Lb and 43Rb, and sets the target regeneration torque of the other stator coil to zero.

[0048] On the other hand, when the required regeneration torque is equal to or greater than a predetermined threshold value, the target torque setting unit 61 determines to regenerate the first motor 11L and the second motor 11R by both the first stator coils 43La and 43Ra and the second stator coils 43Lb and 43Rb. In this case, the target torque setting unit 61 sets a value equal to half of the target regeneration torque of each of the first motor 11L and the second motor 11R to the target regeneration torque of each of the first stator coils 43La and 43Ra or the second stator coils 43Lb and 43Rb.

[0049] Note that the target torque setting unit 61 may always regenerate the first motor 11L and the second motor 11R by both the first stator coils 43La and 43Ra and the second stator coils 43Lb and 43Rb. In this case, the target torque setting unit 61 sets a value equal to half of the target regeneration torque of each of the first motor 11L and the second motor 11R to the target regeneration torque of each of the first stator coils 43La and 43Ra or the second stator coils 43Lb and 43Rb.

[0050] (Motor control unit) The motor control unit 63 controls the driving of the first inverter unit 13L and the second inverter unit 13R, and controls the driving and regeneration of the first motor 11L and the second motor 11R. Specifically, the motor control unit 63 controls the driving of the first inverter unit 13L and the second inverter unit 13R based on the target output torque and the target regeneration torque set for the first stator coils 43La and 43Ra and the second stator coils 43Lb and 43Rb of the first motor 11L and the second motor 11R, respectively.

[0051] More specifically, the motor control unit 63 sets the drive duty ratios of the switching elements provided in the first inverter circuits 13La and 13Ra and the second inverter circuits 13Lb and 13Rb of the first inverter unit 13L and the second inverter unit 13R, respectively, and controls the operation of the switching elements. Thereby, a drive torque corresponding to the target output torque is output from the first motor 11L and the second motor 11R. Alternatively, a braking torque corresponding to the target regeneration torque is generated by the first motor 11L and the second motor 11R.

[0052] (Surrounding environment detection unit) The surrounding environment detection unit 65 detects the surrounding environment of the vehicle 1 based on the detection data transmitted from the surrounding environment sensor 55. Specifically, the surrounding environment detection unit 65 calculates the type, size (width, height, and depth), position, speed, distance from the vehicle 1 to the obstacle, and relative speed between the vehicle 1 and the obstacle of the obstacles existing around the vehicle 1. The detected obstacles include other vehicles during driving, parked vehicles, pedestrians, bicycles, side walls, curbs, buildings, utility poles, traffic signs, traffic signal devices, natural objects, and any other objects existing around the vehicle 1. In the present embodiment, the surrounding environment detection unit 65 acquires at least information on the road shape in front of the vehicle 1.

[0053] The surrounding environment detection unit 65 may refer to the high-precision map data and acquire information on the road shape ahead in the traveling direction of the vehicle 1 based on the position information of the vehicle 1. Specifically, the surrounding environment detection unit 65 identifies the position and traveling direction of the vehicle 1 on the high-precision map data based on the position information of the vehicle 1 transmitted from the GNSS sensor 59, and acquires information on the road shape ahead in the traveling direction of the vehicle 1. The high-precision map data is associated with data on the gradient and radius of curvature of the road, and the surrounding environment detection unit 65 acquires this information on the road shape.

[0054] (Battery diagnosis processing unit) The battery diagnosis processing unit 67 executes a deterioration diagnosis process for the battery 20. In the present embodiment, the battery diagnosis processing unit 67 discharges the battery 20 by driving the first inverter circuits 13La and 13Ra and the second inverter circuits 13Lb and 13Rb of the first inverter unit 13L and the second inverter unit 13R to apply rotational torques in opposite directions to the rotors 41L and 41R of the first motor 11L and the second motor 11R, respectively (hereinafter also referred to as "reverse torque drive"). The battery diagnosis processing unit 67 executes a deterioration diagnosis process for the battery 20 based on the output current or output voltage of the battery 20 during discharge.

[0055] Taking the drive circuit of the motor shown in Fig. 2 as an example, the battery diagnosis processing unit 67 controls the drive of the first inverter unit 13L (the second inverter unit 13R) such that the rotational torque applied to the rotor 41L (41R) by the first stator coil 43La (43Ra) of the first motor 11L (the second motor 11R) and the rotational torque applied to the rotor 41L (41R) by the second stator coil 43Lb (43Rb) are in opposite directions to each other. Thereby, the current values supplied to the first stator coil 43La (43Ra) and the second stator coil 43Lb (43Rb) of the first motor 11L (the second motor 11R) increase by an amount corresponding to the cancellation of the rotational torque. Therefore, the output current and output voltage from the battery 20 can be instantaneously changed without changing the first motor 11L (11R), and the deterioration diagnosis of the battery 20 can be executed based on this output current or output voltage.

[0056] Fig. 4 is an explanatory diagram showing an example of the deterioration diagnosis process of the battery 20. The battery 20 has an internal resistance Rb. The internal resistance Rb increases as the deterioration of the battery 20 progresses. Therefore, the degree of deterioration of the battery 20 can be diagnosed by evaluating the value of the internal resistance Rb. For example, as shown in Fig. 4, a current of a predetermined magnitude is discharged from the battery 20, and the value of the internal resistance Rb can be obtained based on the fluctuation value of the output voltage (terminal voltage) at that time.

[0057] Specifically, when the current value for discharging for the degradation diagnosis of the battery 20 is Id, the voltage fluctuation amount at the start of discharge is ΔV1, and the voltage fluctuation amount at the end of discharge is ΔV2, the internal resistance Rb can be obtained as ΔV1 / Id or ΔV2 / Id. Data obtained in advance regarding the relationship between the value of the internal resistance Rb and the degree of degradation of the battery 20 is stored in the storage unit 53, and by referring to this data, the degree of degradation corresponding to the internal resistance Rb can be estimated. For example, when the estimated internal resistance Rb is equal to or greater than a predetermined threshold value, the battery diagnosis processing unit 67 may determine that the battery 20 is degraded. However, the method for diagnosing the degradation of the battery 20 is not limited to the example shown in FIG. 4, and any other method may be used as long as it can determine the degradation of the battery 20 by discharging from the battery 20.

[0058] In the present embodiment, when the battery diagnosis processing unit 67 executes the degradation diagnosis processing of the battery 20, with respect to the target output torque of either or both of the first stator coils 43La, 43Ra and the second stator coils 43Lb, 43Rb of the first motor 11L or the second motor 11R set by the target torque setting unit 61, output torques in opposite directions and having the same absolute value are added to correct the respective target output torques. For example, an output torque of a predetermined magnitude in the forward rotation direction is added to the target output torque of the first stator coil 43La (43Ra), and an output torque of the same magnitude in the reverse rotation direction is added to the target output torque of the second stator coil 43Lb (43Rb). Thereby, the output current and output voltage from the battery 20 can be instantaneously changed without changing the drive torque output from the first motor 11L (the second motor 11R).

[0059] The deterioration diagnosis process of the battery 20 is executed by instantaneously changing the output current and output voltage from the battery 20 in a state where the target output torque of the first motor 11L (the second motor 11R) is constant. That is, the battery diagnosis processing unit 67 diagnoses the deterioration of the battery 20 based on the magnitude of the variation in the output current or output voltage when the output current and output voltage from the battery 20 are instantaneously changed in a state where they are constant. Thereby, the instantaneous change amount of the output current or output voltage from the state where the output current or output voltage of the battery 20 is stable can be accurately detected, and the degree of deterioration of the battery 20 can be accurately determined.

[0060] For example, after the motor control system 10 is started and before the vehicle 1 starts running, the target output torques of both the first motor 11L and the second motor 11R are in a zero state. Therefore, the battery diagnosis processing unit 67 discharges from the battery 20 while maintaining the output torque of the first motor 11L (the second motor 11R) at zero by applying rotational torques in opposite directions and of the same magnitude to the rotor 41L (41R). In this case, the battery diagnosis processing unit 67 makes the sum of the rotational torque applied to the rotor 41L (41R) by the first stator coil 43La (43Ra) and the rotational torque applied to the rotor 41L (41R) by the second stator coil 43Lb (43Rb) zero. Thereby, it is possible to discharge from the battery 20 without generating a driving force in the vehicle 1.

[0061] On one hand, after starting the running of the vehicle 1, a state where the target output torque of the first motor 11L or the second motor 11R becomes constant for a predetermined time is predicted, and the first motor 11L or the second motor 11R is driven with reverse torque during a period when the target output torque remains constant for a predetermined time or more. At this time, the battery diagnosis processing unit 67 causes the sum of the rotational torque applied to the rotor 41L (41R) by the first stator coil 43La (43Ra) and the rotational torque applied to the rotor 41L (41R) by the second stator coil 43Lb (43Rb) to match the target output torque of the first motor 11L (the second motor 11R). Thereby, while outputting a driving torque corresponding to the required driving torque of the vehicle 1, the output current and the output voltage from the battery 20 can be instantaneously changed.

[0062] For example, the battery diagnosis processing unit 67 adds (subtracts) a constant reverse rotational torque to the target output torque of the first stator coil 43La (43Ra), and adds a forward rotational torque that cancels out the reverse rotational torque to the target output torque of the second stator coil 43Lb (43Rb). Alternatively, the battery diagnosis processing unit 67 adds (subtracts) a constant reverse rotational torque to the target output torque of the second stator coil 43Lb (43Rb), and adds a forward rotational torque that cancels out the reverse rotational torque to the target output torque of the first stator coil 43La (43Ra). However, the method of setting the respective rotational torques applied to the rotor 41L (41R) by the first stator coil 43La (43Ra) and the second stator coil 43Lb (43Rb) is not limited to the above example.

[0063] The predetermined time used for determining the state where the target output torque is constant is set to an arbitrary value equal to or greater than the time for reversely driving the motor for diagnosing the deterioration of the battery 20. In the present embodiment, during the automatic driving of the vehicle 1, the battery diagnosis processing unit 67 determines that the target output torque remains constant for a predetermined time or more when it is predicted that the vehicle 1 travels straight for a predetermined time or more and the acceleration and deceleration of the vehicle 1 do not change, based on the road shape ahead of the traveling direction of the vehicle 1 detected by the surrounding environment detection unit 65. Alternatively, during the automatic driving of the vehicle 1, the battery diagnosis processing unit 67 may determine that the target output torque remains constant for a predetermined time or more when it is predicted that the vehicle 1 travels straight for a predetermined time or more and the acceleration and deceleration of the vehicle 1 do not change, based on the position information of the vehicle 1 acquired from the GNSS sensor 59 and the information on the road shape and the speed limit of the map data.

[0064] When executing the deterioration diagnosis of the battery 20, the battery diagnosis processing unit 67 may reversely drive either one of the first motor 11L or the second motor 11R, or may reversely drive both the first motor 11L and the second motor 11R. For example, the battery diagnosis processing unit 67 reversely drives either one or both of the first motor 11L and the second motor 11R according to a predetermined diagnostic current value required for the deterioration diagnosis set in advance. For example, when it is desired to increase the current value for instantaneously discharging from the battery 20, the battery diagnosis processing unit 67 reversely drives both the first motor 11L and the second motor 11R. When the current value for instantaneously discharging from the battery 20 may be small, the battery diagnosis processing unit 67 reversely drives either the first motor 11L or the second motor 11R. Thereby, the power loss due to the driving of the switching elements of the first inverter circuits 13La, 13Ra and the second inverter circuits 13Lb, 13Rb can be reduced.

[0065] Alternatively, the battery diagnosis processing unit 67 may vary the ratio of the currents supplied to the first motor 11L and the second motor 11R according to the temperatures of the first motor 11L and the second motor 11R. For example, when the current value increased for the deterioration diagnosis of the battery 20 is Id, if both the temperature Tm1 of the first motor 11L output from the first motor temperature sensor 15L and the temperature Tm2 of the second motor 11R output from the second motor temperature sensor 15R are less than a predetermined reference temperature T0, the ratio of the currents supplied to the first motor 11L and the second motor 11R is set to 5:5. Thereby, while suppressing the rise in the temperature of each of the first motor 11L and the second motor 11R, it is possible to discharge the current necessary for the deterioration diagnosis of the battery 20. On the other hand, when either the temperature Tm1 of the first motor 11L or the temperature Tm2 of the second motor 11R is equal to or higher than the predetermined reference temperature T0, the ratio of the current supplied to the motor with the lower temperature is set to 10. Thereby, a further rise in the temperature of the motor with the higher temperature is suppressed.

[0066] Further, when the remaining capacity of the battery 20 is equal to or greater than a predetermined threshold value, the battery diagnosis processing unit 67 may execute a process of applying rotational torques in opposite directions to the rotor 41L (41R) to perform a deterioration diagnosis of the battery 20. Thereby, it is possible to prevent the remaining capacity of the battery 20 from decreasing due to the deterioration diagnosis process of the battery 20, and prevent the charging of the battery 20 from running out or the cruising range from shortening.

[0067] <4. Processing operation example> So far, the configuration example of the motor control system 10 according to the present embodiment has been described. Subsequently, an example of the battery deterioration diagnosis processing operation by the control device 50 of the motor control system 10 will be described with reference to a flowchart.

[0068] FIG. 5 is a flowchart showing an example of the battery deterioration diagnosis processing operation by the control device 50 according to the present embodiment.

[0069] First, when the drive system of vehicle 1 is activated (step S11), the battery diagnosis processing unit 67 of the processing unit 51 determines whether the remaining capacity SOC of the battery 20 is equal to or greater than a predetermined threshold value SOC_thr (step S13). Specifically, the battery diagnosis processing unit 67 acquires information on the remaining capacity SOC of the battery 20 transmitted from the battery management device 21 and determines whether the remaining capacity SOC is equal to or greater than the predetermined threshold value SOC_thr. Here, it is determined whether it is possible to perform reverse torque drive on the rotors 41L and 41R without causing an output shortage of the battery 20. The predetermined threshold value SOC_thr may be determined according to the set value of the rotational torque to be canceled by the reverse torque drive. That is, the larger the set value of the rotational torque to be canceled, the larger the output current of the battery 20 to be output in the reverse torque drive, so the predetermined threshold value SOC_thr is set to a larger value.

[0070] When it is determined that the remaining capacity SOC of the battery 20 is less than the predetermined threshold value SOC_thr (S13 / No), the battery diagnosis processing unit 67 determines whether the motor control system 10 has stopped (step S15). If it is determined that the motor control system 10 has stopped (S15 / Yes), the deterioration diagnosis process of the battery 20 is terminated. On the other hand, when it is determined that the motor control system 10 has not stopped (S15 / No), the battery diagnosis processing unit 67 repeatedly executes the determination in step S13.

[0071] When it is determined that the remaining capacity SOC of the battery 20 is equal to or greater than the predetermined threshold value SOC_thr (S13 / No), the battery diagnosis processing unit 67 determines whether vehicle 1 is in a state before starting to run (step S17). For example, the battery diagnosis processing unit 67 may determine that vehicle 1 is in a state before starting to run when the required drive torque calculated based on the accelerator opening or the required acceleration information after the activation of the motor control system 10 is not a positive value exceeding zero. However, the method for determining whether vehicle 1 is in a state before starting to run is not limited to the above example.

[0072] When it is determined that the vehicle 1 is in a state before starting running (S17 / Yes), the battery diagnosis processing unit 67 executes pre-start running diagnosis processing (step S19). On the other hand, when it is not determined that the vehicle 1 is in a state before starting running (S17 / No), the battery diagnosis processing unit 67 executes post-start running diagnosis processing (step S21).

[0073] FIG. 6 is a flowchart showing an example of pre-start running diagnosis processing. In a state before starting running of the vehicle 1, at least one of the first motor 11L and the second motor 11R is driven with reverse torque so that no driving torque is output from the first motor 11L and the second motor 11R.

[0074] The battery diagnosis processing unit 67 determines whether or not the temperature Tm1 of the first motor 11L and the temperature Tm2 of the second motor 11R are both less than a predetermined reference temperature Tm_thr (step S31). Specifically, the battery diagnosis processing unit 67 acquires information on the temperature Tm1 of the first motor 11L output from the first motor temperature sensor 15L provided in the first motor 11L and information on the temperature Tm2 of the second motor 11R output from the second motor temperature sensor 15R provided in the second motor 11R, and determines whether or not the temperature Tm1 of the first motor 11L and the temperature Tm2 of the second motor 11R are each less than a predetermined reference temperature Tm_thr set in advance. The predetermined reference temperature Tm_thr is set to an arbitrary appropriate value according to the value of the allowable upper limit temperature.

[0075] When the temperature Tm1 of the first motor 11L and the temperature Tm2 of the second motor 11R are both less than the predetermined reference temperature Tm_thr (S31 / Yes), the battery diagnosis processing unit 67 sets the current value Im1 supplied to the first motor 11L and the current value Im2 supplied to the second motor 11R to half the current value Id required for deterioration diagnosis. Then, the first motor 11L and the second motor 11R are driven with reverse torque so that the output torque of each of the first motor 11L and the second motor 11R becomes zero (step S33).

[0076] Specifically, the battery diagnosis processing unit 67 controls the driving of the first inverter circuit 13La and the second inverter circuit 13Lb of the first inverter unit 13L, and applies rotational torques that are opposite to each other and have the same magnitude to the rotor 41L of the first motor 11L. Similarly, the battery diagnosis processing unit 67 controls the driving of the first inverter circuit 13Ra and the second inverter circuit 13Rb of the second inverter unit 13R, and applies rotational torques that are opposite to each other and have the same magnitude to the rotor 41R of the second motor 11R. Thereby, while suppressing the temperature rise of the first motor 11L and the second motor 11R, it is possible to discharge an instantaneous current for deterioration diagnosis from the battery 20 while maintaining the outputs from the first motor 11L and the second motor 11R at zero.

[0077] When either the temperature Tm1 of the first motor 11L or the temperature Tm2 of the second motor 11R is not less than a predetermined reference temperature Tm_thr (S31 / No), the battery diagnosis processing unit 67 determines whether the temperature Tm1 of the first motor 11L is less than the predetermined reference temperature Tm_thr (step S35). When the temperature Tm1 of the first motor 11L is less than the predetermined reference temperature Tm_thr (S35 / Yes), the battery diagnosis processing unit 67 sets the current value Im1 supplied to the first motor 11L to the current value Id required for deterioration diagnosis, while setting the current value Im2 supplied to the second motor 11R to zero. Then, the first motor 11L is driven with reverse torque so that the output torque of the first motor 11L becomes zero (step S37). Thereby, while suppressing the temperature rise of the second motor 11R, it is possible to discharge an instantaneous current for deterioration diagnosis from the battery 20 while maintaining the outputs from the first motor 11L and the second motor 11R at zero.

[0078] On the other hand, when the temperature Tm1 of the first motor 11L is not less than a predetermined reference temperature Tm_thr (S35 / No), the battery diagnosis processing unit 67 determines whether the temperature Tm2 of the second motor 11R is less than the predetermined reference temperature Tm_thr (step S39). When the temperature Tm2 of the second motor 11R is less than the predetermined reference temperature Tm_thr (S39 / Yes), the battery diagnosis processing unit 67 sets the current value Im1 supplied to the first motor 11L to zero, while setting the current value Im2 supplied to the second motor 11R to the current value Id required for deterioration diagnosis. Then, the second motor 11R is driven with reverse torque so that the output torque of the second motor 11R becomes zero (step S41). Thereby, while suppressing the temperature rise of the first motor 11L, it is possible to discharge the instantaneous current for deterioration diagnosis from the battery 20 while maintaining the output from the first motor 11L and the second motor 11R at zero.

[0079] On the other hand, when the temperature Tm2 of the second motor 11R is not less than the predetermined reference temperature Tm_thr (S39 / No), in order to prevent the first motor 11L and the second motor 11R from entering an overheated state, reverse torque driving is not executed for either the first motor 11L or the second motor 11R. In this case, the battery diagnosis processing unit 67 ends the pre-travel diagnosis processing without calculating the internal resistance Rb of the battery 20.

[0080] When discharging from the battery 20 by reversely torque-driving either one or both of the first motor 11L and the second motor 11R in steps S33, S37, and S41 respectively, the battery diagnosis processing unit 67 calculates the internal resistance Rb of the battery 20 based on the voltage fluctuation value ΔV (ΔV1 or ΔV2) at the start or end of the discharge (step S43). Specifically, the battery diagnosis processing unit 67 acquires information on the output voltage of the battery 20 transmitted from the battery management device 21, and obtains the voltage fluctuation value ΔV1 at the start or the voltage fluctuation value ΔV2 at the end of the reverse torque drive of either one or both of the first motor 11L and the second motor 11R. Then, the battery diagnosis processing unit 67 calculates and records the internal resistance Rb (=ΔV / Id) based on the current value Id discharged from the battery 20 and the voltage fluctuation value ΔV.

[0081] Figs. 7 to 8 are flowcharts showing an example of the diagnosis processing after the start of running. After the start of running of the vehicle 1, the first motor 11L and the second motor 11R are reversely torque-driven so that drive torques corresponding to the target output torques are output from the first motor 11L and the second motor 11R respectively.

[0082] The battery diagnosis processing unit 67 determines whether or not the cruise control function is activated (step S51). The cruise control function is a function that automatically causes the host vehicle to follow a preceding vehicle while maintaining a vehicle-to-vehicle distance corresponding to the vehicle speed when the preceding vehicle is within a predetermined distance, and automatically runs the host vehicle while maintaining the set vehicle speed when the preceding vehicle is not within the predetermined distance. When the cruise control function is not activated (S51 / No), the battery diagnosis processing unit 67 ends the diagnosis processing after the start of running.

[0083] On the other hand, when the cruise control function is activated (S51 / Yes), the battery diagnosis processing unit 67 determines whether it is predicted that the target output torques of the first motor 11L and the second motor 11R will be in a constant state for a predetermined time or more (step S53). For example, the battery diagnosis processing unit 67 determines whether it is predicted that the target output torques of the first motor 11L and the second motor 11R will be in a constant state for a predetermined time or more based on the road shape ahead of the vehicle 1 detected by the ambient environment detection unit 65, the situation of other vehicles around the vehicle 1, the speed of the vehicle 1, etc. Specifically, when the vehicle 1 is traveling straight on a straight road, there is no situation where the traveling of the vehicle 1 is obstructed, and the vehicle 1 is traveling stably at a constant speed, the battery diagnosis processing unit 67 determines whether it is predicted that the target output torques of the first motor 11L and the second motor 11R will be in a constant state for a predetermined time or more.

[0084] Note that the battery diagnosis processing unit 67 specifies the position and traveling direction of the vehicle 1 on the high-precision map data based on the position data of the vehicle 1 transmitted from the GNSS sensor 59, and determines whether it is predicted that the target output torques of the first motor 11L and the second motor 11R will be in a constant state for a predetermined time or more based on the information on the road shape and the speed limit ahead of the traveling direction of the vehicle 1 and the information on the vehicle speed of the vehicle 1. The high-precision map data may be stored in the storage unit 53, or may be stored in an external server that can be connected via wireless communication means. Also, in order to estimate whether the target output torque fluctuates due to the acceleration and deceleration of the vehicle 1, traffic jam information may be acquired from an external system.

[0085] When it is not predicted that the target output torques of the first motor 11L and the second motor 11R will be in a constant state for a predetermined time or more (S53 / No), the battery diagnosis processing unit 67 ends the diagnosis processing after the start of travel. On the other hand, when it is predicted that the target output torques of the first motor 11L and the second motor 11R will be in a constant state for a predetermined time or more (S53 / Yes), the battery diagnosis processing unit 67 acquires information on the target output torques of the first motor 11L and the second motor 11R respectively (step S55). Specifically, the target torque setting unit 61 sets the target output torques of the first motor 11L and the second motor 11R based on the required drive torque of the vehicle 1. The required drive torque is calculated based on the operation amount of the accelerator pedal and the vehicle speed during manual driving. Also, the required drive torque is calculated based on the required acceleration obtained by calculation during automatic driving. The battery diagnosis processing unit 67 acquires the calculation result of the target output torque by the target torque setting unit 61.

[0086] Next, the battery diagnosis processing unit 67 determines, in the same manner as in step S31 described above, whether or not both the temperature Tm1 of the first motor 11L and the temperature Tm2 of the second motor 11R are less than a predetermined reference temperature Tm_thr (step S57). When both the temperature Tm1 of the first motor 11L and the temperature Tm2 of the second motor 11R are less than the predetermined reference temperature Tm_thr (S57 / Yes), the battery diagnosis processing unit 67 sets the current value Im1X to be added to the supply current value to the first motor 11L and the current value Im2X to be added to the supply current value to the second motor 11R to half the value of the current value Id required for deterioration diagnosis. Then, the first motor 11L and the second motor 11R are driven with reverse torque so that the output torques of the first motor 11L and the second motor 11R respectively become the target output torques (step S59).

[0087] Specifically, the battery diagnosis processing unit 67 controls the driving of the first inverter circuit 13La and the second inverter circuit 13Lb of the first inverter unit 13L, and applies additional rotational torques to the rotor 41L of the first motor 11L that are in opposite directions to each other and have the same magnitude. More specifically, for example, a reverse rotational torque corresponding to a value half of the current value Id required for deterioration diagnosis is added (subtracted) to the rotational torque of the first stator coil 43La, and a forward rotational torque corresponding to a value half of the current value Id required for deterioration diagnosis is added to the rotational torque of the second stator coil 43Lb. Similarly, the battery diagnosis processing unit 67 controls the driving of the first inverter circuit 13Ra and the second inverter circuit 13Rb of the second inverter unit 13R, and applies rotational torques to the rotor 41R of the second motor 11R that are in opposite directions to each other and have the same magnitude. Thereby, while using the driving torques output from the first motor 11L and the second motor 11R as the target output torque, an instantaneous current for deterioration diagnosis can be discharged from the battery 20.

[0088] On the other hand, when either the temperature Tm1 of the first motor 11L or the temperature Tm2 of the second motor 11R is not less than a predetermined reference temperature Tm_thr (S57 / No), the battery diagnosis processing unit 67 determines whether the temperature Tm1 of the first motor 11L is less than the predetermined reference temperature Tm_thr in the same manner as in step S35 above (step S61). When the temperature Tm1 of the first motor 11L is less than the predetermined reference temperature Tm_thr (S61 / Yes), the battery diagnosis processing unit 67 sets the current value Im1X added to the supply current value to the first motor 11L to the current value Id required for deterioration diagnosis, while setting the current value Im2X added to the supply current value to the second motor 11R to zero. Then, the first motor 11L is driven with reverse torque so that the output torques of the first motor 11L and the second motor 11R respectively become the target output torque (step S63). Thereby, an increase in the temperature of the second motor 11R can be suppressed, and while using the driving torques output from the first motor 11L and the second motor 11R as the target output torque, an instantaneous current for deterioration diagnosis can be discharged from the battery 20.

[0089] On the other hand, when the temperature Tm1 of the first motor 11L is not less than the predetermined reference temperature Tm_thr (S61 / No), the battery diagnosis processing unit 67 determines whether or not the temperature Tm2 of the second motor 11R is less than the predetermined reference temperature Tm_thr in the same manner as in step S39 described above (step S65). When the temperature Tm2 of the second motor 11R is less than the predetermined reference temperature Tm_thr (S65 / Yes), the battery diagnosis processing unit 67 sets the current value Im1X to be added to the supply current value to the first motor 11L to zero, while setting the current value Im2X to be added to the supply current value to the second motor 11R to the current value Id required for deterioration diagnosis. Then, the second motor 11R is driven with reverse torque so that the output torque of each of the first motor 11L and the second motor 11R becomes the target output torque (step S67). Thereby, it is possible to suppress the temperature rise of the first motor 11L and discharge the instantaneous current for deterioration diagnosis from the battery 20 while making the drive torque output from the first motor 11L and the second motor 11R the target output torque.

[0090] On the other hand, when the temperature Tm2 of the second motor 11R is not less than the predetermined reference temperature Tm_thr (S65 / No), in order to prevent the first motor 11L and the second motor 11R from becoming overheated, reverse torque drive is not executed for either the first motor 11L or the second motor 11R. In this case, the battery diagnosis processing unit 67 ends the diagnosis processing after starting running without calculating the internal resistance Rb of the battery 20.

[0091] When discharging from the battery 20 by driving either one or both of the first motor 11L and the second motor 11R with reverse torque in steps S59, S61, and S65, the battery diagnosis processing unit 67 calculates the internal resistance Rb of the battery 20 based on the voltage fluctuation value ΔV (ΔV1 or ΔV2) at the start or end of discharge in the same manner as in step S43 described above (step S69).

[0092] Returning to FIG. 5, after executing the pre-travel diagnosis process or the post-travel diagnosis process, the battery diagnosis processing unit 67 determines whether or not the calculated internal resistance Rb of the battery 20 is equal to or greater than a predetermined threshold value (step S23). The threshold value is set to an arbitrary value in advance. If the internal resistance Rb of the battery 20 is less than the predetermined threshold value (S23 / No), the battery diagnosis processing unit 67 ends the battery degradation diagnosis process without determining that the battery 20 is degraded. On the other hand, if the internal resistance Rb of the battery 20 is less than the predetermined threshold value (S23 / No), the battery diagnosis processing unit 67 notifies the driver or other passengers that the battery 20 is degraded (step S25), and ends the battery degradation diagnosis process. The notification that the battery 20 is degraded may be a voice notification, or may be a notification by an image display or text display on a warning lamp or a display unit.

[0093] As described above, the motor control system 10 according to the present embodiment drives the first inverter circuits 13La (13Ra) and the second inverter circuits 13Lb (13Rb) respectively connected to the first motor 11L and the second motor 11R, and applies rotational torques in opposite directions to the rotors 41L (41R) of the first motor 11L and the second motor 11R. Thereby, without changing the output torques from the first motor 11L and the second motor 11R from the target output torque (including zero), the current corresponding to the canceling rotational torque is discharged from the battery 20 as an instantaneous current. Then, the battery diagnosis processing unit 67 can diagnose the degradation of the battery 20 based on the fluctuation value of the voltage of the battery 20 when the instantaneous current is discharged from the battery 20. Therefore, the degree of freedom in the execution timing of the degradation diagnosis of the battery 20 can be increased without using a load device for discharging.

[0094] Also, in the motor control system 10 according to the present embodiment, even after the vehicle 1 starts running, the battery diagnosis processing unit 67 predicts a state in which the target output torques of the first motor 11L and the second motor 11R remain constant for a predetermined time, and drives either one or both of the first motor 11L and the second motor 11R in reverse torque during the predicted period. For this reason, from a state where the output voltage is stable, it is possible to detect the voltage fluctuation value due to the discharge of the instantaneous current, accurately detect the internal resistance Rb of the battery 20 based on the voltage fluctuation value, and improve the accuracy of the deterioration diagnosis of the battery 20.

[0095] <5. Modification example> So far, the motor control system according to the present embodiment has been described. However, the above embodiment can be variously modified. Some of the modification examples will be described below.

[0096] In the above embodiment, a two-wheel drive vehicle equipped with a first motor for driving the left rear wheel and a second motor for driving the right rear wheel has been described as an example. However, the drive system of the electric vehicle is not limited to the above example. For example, the electric vehicle may be a four-wheel drive vehicle equipped with two motors capable of independently driving the front wheels or the rear wheels.

[0097] Also, the electric vehicle may be a two-wheel drive vehicle or a four-wheel drive vehicle equipped with one motor for driving either one or both of the front wheels or the rear wheels. In this case, the control device can discharge the instantaneous current from the battery by executing reverse torque drive on one motor, and execute the deterioration diagnosis of the battery.

[0098] As described above, the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. However, the present disclosure is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field to which the present disclosure pertains can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and these are also naturally understood to belong to the technical scope of the present disclosure.

Explanation of reference numerals

[0099] 1: Vehicle, 10: Motor control system, 11L: First motor, 11R: Second motor, 13L: First inverter unit, 13La - 13Ra: First inverter circuit, 13Lb - 13Rb: Second inverter circuit, 13R: Second inverter unit, 15L: First motor temperature sensor, 15R: Second motor temperature sensor, 20: Battery, 21: Battery management device, 41L - 41R: Rotor, 43La - 43Ra: First stator coil, 43Lb - 43Rb: Second stator coil, 50: Control device, 51: Processing unit, 53: Storage unit, 57: Vehicle state sensor, 61: Target torque setting unit, 63: Motor control unit, 65: Surrounding environment detection unit, 67: Battery diagnosis processing unit

Claims

1. In an electric vehicle motor control system comprising a battery, a motor having a rotor and a stator, two inverter circuits connected to the stator for controlling driving and regeneration of the motor respectively, and a control device for controlling driving of the two inverter circuits, after at least starting the running of the electric vehicle, the control device drives the two inverter circuits respectively to additionally apply rotational torques that are opposite to each other and cancel each other out to the rotor, thereby discharging the battery without changing the output torque from the motor from the target output torque, and executes a deterioration diagnosis process of the battery based on the output current or output voltage of the battery during discharging. An electric vehicle motor control system.

2. The control device after starting the motor control system and before starting the running of the electric vehicle, applies rotational torques that are opposite to each other and of the same magnitude to the rotor, thereby discharging the battery while maintaining the output torque of the motor at zero, and executes a deterioration diagnosis process of the battery. The electric vehicle motor control system according to Claim 1.

3. The control device acquires information on the remaining capacity of the battery, and executes a deterioration diagnosis process of the battery when the remaining capacity is equal to or greater than a predetermined threshold. The electric vehicle motor control system according to Claim 1.

4. In an electric vehicle comprising a battery, a motor having a rotor and a stator, two inverter circuits connected to the stator for controlling driving and regeneration of the motor respectively, and a control device for controlling driving of the two inverter circuits, after at least starting the running of the electric vehicle, the control device drives the two inverter circuits respectively to additionally apply rotational torques that are opposite to each other and cancel each other out to the rotor, thereby discharging the battery without changing the output torque from the motor from the target output torque, and executes a deterioration diagnosis process of the battery based on the output current or output voltage of the battery during discharging. An electric vehicle.

5. In a motor control system for an electric vehicle, comprising a battery, a motor having a rotor and a stator, two inverter circuits connected to the stator for controlling driving and regeneration of the motor respectively, and a control device for controlling driving of the two inverter circuits, the control device drives the two inverter circuits respectively to apply rotational torques in opposite directions to the rotor to discharge the battery, and executes a deterioration diagnosis process of the battery based on an output current or an output voltage of the battery during discharge; A motor control system for an electric vehicle, the control device predicts a state in which a target output torque of the motor remains constant for a predetermined time or more, during a period in which the target output torque remains constant for a predetermined time or more, discharges the battery by applying rotational torques in opposite directions to the rotor so that an output torque from the motor is maintained at the target output torque, and executes a deterioration diagnosis process of the battery; A motor control system for an electric vehicle.

6. The control device predicts that the target output torque of the motor is in a state of remaining constant for a predetermined time or more when it is predicted that the electric vehicle travels straight for a predetermined time or more and the acceleration and deceleration do not change during automatic driving of the electric vehicle; The motor control system for an electric vehicle according to claim 5.

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