Motor control system for electric vehicle and electric vehicle

Abstract

This motor control system for an electric automobile comprising a battery, a motor having a rotor and a stator, two inverter circuits that are connected to the stator and respectively control the driving and regeneration of the motor, and a control device that controls the driving of the two inverter circuits, comprises a cooling water circuit for circulation at least through the battery and the motor, wherein the control device executes a process for driving a cooling water pump and causing cooling water to circulate, respectively drives the two inverter circuits to apply rotation torques in opposite directions to the rotor, and warms up the battery with the cooling water heated up by the heating of the motor.

Description

[Technical field]

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

[0002] It is known that the charge / discharge performance of a battery mounted on an electric vehicle equipped with a drive motor as a drive source for the vehicle is degraded in a low-temperature environment such as in a cold region. For this reason, a process of warming up the battery is performed by a means for heating the battery.

[0003] For example, Patent Document 1 discloses a battery temperature control device that includes a motor for running a vehicle, a battery that supplies power to the motor and has an optimal operating temperature near room temperature, a heat-generating component that generates heat when the vehicle is started, a radiator that dissipates heat generated by the battery to the outside of the vehicle, a heater core that dissipates heat generated by the battery into the vehicle, a battery temperature detection sensor that detects the temperature of the battery, and a control circuit that heats the battery using heat generated by the heat-generating component when the battery temperature is lower than the appropriate range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 06-24238 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the battery temperature control device of Patent Document 1 uses a motor and an inverter as heat generating members that generate heat when the vehicle is started, but the heat generated when the motor and the inverter are used in normal use after the vehicle is started does not continue at a high temperature. In particular, in a low temperature environment such as a cold region, the heat generated when the motor and the inverter are used in normal use does not easily become high. For this reason, it takes time to warm up the battery, and it takes time for the battery's charge and discharge performance to recover.

[0006] The present disclosure has been made in consideration of the above problems, and an object of the present disclosure is to provide a motor control system for an electric vehicle and an electric vehicle that can shorten the time required to warm up the battery that supplies power to the motor. [Means for solving the problem]

[0007] In order to solve the above problems, according to one aspect of the present disclosure, there is provided 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 and respectively controlling drive and regeneration of the motor, and a control device controlling drive of the two inverter circuits, a cooling water circuit having a cooling water pump and circulating through at least the battery and the motor; The control device includes: The present invention provides a motor control system for an electric vehicle, which drives the cooling water pump to circulate the cooling water, and drives the two inverter circuits to apply rotational torque in opposite directions to the rotor, thereby warming up the battery with the cooling water that is heated by heat generated by the motor, and an electric vehicle equipped with the motor control system. Effect of the Invention

[0008] As described above, according to the present disclosure, it is possible to reduce the time required to warm up a battery that supplies power to a motor of an electric vehicle. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a configuration example of an electric vehicle equipped with a motor control system according to an embodiment of the present disclosure. [Diagram 2] 2 is a circuit diagram showing a motor drive circuit of the motor control system according to the embodiment. FIG. [Diagram 3] FIG. 2 is a block diagram showing an example of the configuration of a control device of the motor control system according to the embodiment. [Figure 4] 6 is a flowchart showing an example of an operation of a battery warm-up process performed by the motor control system according to the embodiment; [Diagram 5] 5 is a flowchart showing an example of an operation of a pre-travel start warm-up process performed by the motor control system according to the embodiment; [Figure 6] 4 is an explanatory diagram showing the temperature of the motor during pre-travel warm-up processing by the motor control system according to the embodiment; FIG. [Figure 7] 5 is a flowchart showing an example of an operation of a warm-up process after starting traveling performed by the motor control system according to the embodiment; [Figure 8] FIG. 13 is a schematic diagram showing a configuration example of a vehicle equipped with a motor control system according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0011] <1. Motor control system configuration> 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 this embodiment. As shown in the figure, the vehicle 1 is a four-wheeled vehicle equipped with 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 four-wheel drive vehicle equipped with a first motor 11F and a second motor 11R as a driving force source that generates a driving torque for the vehicle 1. The first motor 11F and the second motor 11R drive the front wheels and the rear wheels independently, respectively.

[0013] The motor control system 10 includes a first motor 11F, a second motor 11R, a first inverter unit 13F, a second inverter unit 13R, a battery 20, a coolant circuit 30, and a control device 50. The first motor 11F and the second motor 11R are, for example, three-phase AC radial motors or axial gap motors. However, the number of phases is not particularly limited. The first motor 11F outputs a drive torque transmitted to the left and right front wheels 3F via the differential mechanism 7F and the left front wheel drive shaft 5LF or the right front wheel drive shaft 5RF. The second motor 11R outputs a drive torque transmitted to the left and right rear wheels 3R ​​via the differential mechanism 7R and the left rear wheel drive shaft 5LR and the right rear wheel drive shaft 5RR.

[0014] Furthermore, the first motor 11F and the second motor 11R have a function of performing regenerative power generation by receiving the rotational torque of the front wheels 3F or the rear wheels 3R ​​transmitted via the left front drive shaft 5LF, the right front drive shaft 5RF, the left rear drive shaft 5LR, and the right rear drive shaft 5RR during deceleration of the vehicle 1. The drive and regeneration of the first motor 11F and the second motor 11R are controlled by the control device 50.

[0015] The first motor 11F and the second motor 11R are each determined to have a rated output torque capable of continuously outputting a stable torque. The rated output torques of the first motor 11F and the second motor 11R may be the same or different. For example, when emphasis is placed on the running stability of the vehicle 1, the rated output torque of the first motor 11F is set to be larger than the rated output torque of the second motor 11R. Also, when emphasis is placed on the turning performance of the vehicle 1, the rated output torque of the second motor 11R is set to be larger than the rated output torque of the first motor 11F.

[0016] The first motor 11F is equipped with a first motor temperature sensor 15F. The second motor 11R is equipped with a second motor temperature sensor 15R. The first motor temperature sensor 15F and the second motor temperature sensor 15R each detect the temperature of the motor and transmit information on the detected temperature to the control device 50.

[0017] The battery 20 is configured to include a plurality of battery cells that are chargeable and dischargeable secondary batteries. The battery 20 may be, for example, a lithium ion battery rated at 200 V, but the rated voltage and type of the battery 20 are not particularly limited.

[0018] The battery 20 is connected to the first motor 11F and the second motor 11R via the first inverter unit 13F and the second inverter unit 13R, and stores the power to be supplied to the first motor 11F and the second motor 11R. The battery 20 is provided with a battery management device 21 that detects the output current, output voltage, battery temperature, etc. of the battery 20 and transmits them to the control device 50.

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

[0020] The second inverter unit 13R controls the drive and regeneration of the second motor 11R. In this embodiment, the second inverter unit 13R has 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. In addition, 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 and charge the battery 20. The drive of the second inverter unit 13R is controlled by the control device 50.

[0021] The coolant circuit 30 includes a coolant pump 31, a radiator 33, a coolant circulation passage 35, and a coolant temperature sensor 37. The coolant pump 31 is driven by a current supply and pumps the coolant. The radiator 33 cools the coolant passing through it by heat exchange. The coolant temperature sensor 37 detects the temperature of the coolant, and outputs a sensor signal including information indicating the coolant temperature to the control device 50.

[0022] In the illustrated coolant circuit 30, the coolant discharged by the coolant pump 31 passes through the battery 20, the second motor 11R, the second inverter unit 13R, the first inverter unit 13F, the first motor 11F, and the radiator 33 in this order, and then circulates to the coolant pump 31. The coolant receives heat from the battery 20, the second motor 11R, the second inverter unit 13R, the first inverter unit 13F, and the first motor 11F, and cools the battery 20, the second motor 11R, the second inverter unit 13R, the first inverter unit 13F, and the first motor 11F by heat exchange. The coolant is also cooled by discharging heat while passing through the radiator 33.

[0023] The position of the coolant temperature sensor 37 is not limited to the example shown in the figure. However, in order to detect the temperature of the coolant supplied to the battery 20, it is desirable to place the coolant temperature sensor 37 between the radiator 33 and the battery 20. In addition, as will be described later, the coolant circuit 30 is also used for warm-up control of the battery 20.

[0024] The control device 50 functions as a device that controls the driving of the first motor 11F 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 the operation to be performed by the control device 50, which will be described later. 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 that can be externally attached to the control device 50.

[0025] The recording medium for recording a computer program may be a magnetic medium such as a hard disk, a floppy disk, or a magnetic tape; an optical recording medium such as a CD-ROM (Compact Disk Read Only Memory), a DVD (Digital Versatile Disk), an SSD (Solid State Drive), or a Blu-ray (registered trademark); a magnetic optical medium such as a floptical disk; a memory element such as a RAM or a ROM; a flash memory such as a USB (Universal Serial Bus) memory; or any other medium capable of storing a program.

[0026] The first motor temperature sensor 15F, the second motor temperature sensor 15R, the battery management device 21, the coolant temperature sensor 37, and the vehicle condition sensor 57 are connected to the control device 50 via a dedicated line or a communication means such as a controller area network (CAN) or a local inter net (LIN). The first inverter unit 13F and the second inverter unit 13R are also connected to the control device 50 via a dedicated line or a communication means such as a CAN or a local inter net. The functional configuration of the control device 50 will be described in detail later.

[0027] The vehicle state sensor 57 is composed 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. The vehicle state sensor 57 may also include, for example, at least one of 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.

[0028] <2. Motor drive circuit configuration> Next, the configuration of a motor drive circuit of the motor control system according to this embodiment will be described.

[0029] Fig. 2 shows a circuit diagram of the drive circuits of the first motor 11F and the second motor 11R. The drive circuit of the first motor 11F and the drive circuit of the second motor 11R have the same configuration. Therefore, Fig. 2 shows the drive circuit of one motor.

[0030] In this embodiment, the first motor 11F has one rotor 41F and two sets of three-phase stator coils 43Fa, 43Fb. 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 to one stator. When the motor is a double stator type axial gap motor, a three-phase stator coil is assembled to each of two stators arranged on both sides of the rotor in the axial direction.

[0031] The first inverter circuit 13Fa (13Ra) and the second inverter circuit 13Fb (13Rb) each include a plurality of switching elements. The driving of each switching element of the first inverter circuit 13Fa (13Ra) and the second inverter circuit 13Fb (13Rb) is controlled by the control device 50.

[0032] The first inverter circuit 13Fa (13Ra) is electrically connected to the first stator coil 43Fa (43Ra) of the first motor 11F (second motor 11R). The first inverter circuit 13Fa (13Ra) includes three arm circuits 45u, 45v, and 45w (hereinafter, collectively referred to as arm circuits 45 unless otherwise specified). The arm circuit 45u is electrically connected to the u-phase coil of the first stator coil 43Fa (43Ra) of the first motor 11F (second motor 11R). The arm circuit 45v is electrically connected to the v-phase coil of the first stator coil 43Fa (43Ra) of the first motor 11F (second motor 11R). The arm circuit 45w is electrically connected to the w-phase coil of the first stator coil 43Fa (43Ra) of the first motor 11F (second motor 11R).

[0033] 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. The upper arm and the lower arm of each arm circuit 45 are provided with switching elements 47u, 49u, 47v, 49v, 47w, and 49w to which diodes are electrically connected in anti-parallel. The switching elements 47u, 49u, 47v, 49v, 47w, and 49w may be, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors), but may also be other switching elements.

[0034] In the first motor 11F (second motor 11R), three-phase AC power is supplied to either or both of the first stator coil 43Fa (43Ra) and the second stator coil 43Fb (43Rb) by driving the first inverter circuit 13Fa (13Ra) and the second inverter circuit 13Fb (13Rb), so that the rotor 41F (41R) is rotated and driven to output a drive torque. In addition, in the first motor 11F (second motor 11R), regenerative power is supplied to the battery 20 by either or both of the first stator coil 43Fa (43Ra) and the second stator coil 43Fb (43Rb) by driving the first inverter circuit 13Fa (13Ra) and the second inverter circuit 13Fb (13Rb).

[0035] In addition, a voltage is applied between the battery 20 and each inverter circuit. Buck-boost A converter circuit may be provided for this purpose.

[0036] <3. Control device> Next, the configuration of the control device 50 will be described in detail. In the following description, rotation of the first motor 11F and the second motor 11R in the forward direction of the vehicle 1 is referred to as "forward rotation," and rotation of the first motor 11F and the second motor 11R in the backward direction of the vehicle 1 is referred to as "reverse rotation."

[0037] FIG. 3 is a block diagram showing the functional configuration of the control device 50 of the motor control system 10 according to this embodiment. The control device 50 includes a processing unit 51 and a storage unit 53. The processing unit 51 includes one or more processors such as CPUs. A part or all of the processing unit 51 may be configured with an updatable firmware or the like, or may be a program module or the like executed by a command from the CPU or the like. The storage unit 53 includes 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 units 53 are not particularly limited. The storage unit 53 stores information such as computer programs executed by the processing unit 51, various parameters used in the calculation process, detection data, and calculation results.

[0038] The processing unit 51 of the control device 50 includes a target torque setting unit 61, a motor control unit 63, a cooling water circuit control unit 65, and a battery warm-up control unit 67. Each of these units may have a function realized by a processor such as a CPU executing a computer program, or may be partially configured by an analog circuit. Below, the function of each unit of the processing unit 51 will be briefly described, and then specific processing operations will be described.

[0039] (Target torque setting section) The target torque setting unit 61 sets the target torques of the first motor 11F and the second motor 11R when the warm-up process of the battery 20 is stopped. In this embodiment, when the warm-up process of the battery 20 is being executed, the target torques of the first motor 11F and the second motor 11R are set by a battery warm-up control unit 67, which will be described later.

[0040] Specifically, when the warm-up process of the battery 20 is stopped, the target torque setting unit 61 sets the target output torques of the first motor 11F and the second motor 11R based on the required driving torque of the vehicle 1. The required driving torque is calculated based on the accelerator pedal operation amount 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.

[0041] The target torque setting unit 61 sets the ratio between the target output torque of the first motor 11F and the target output torque of the second motor 11R to a preset driving torque ratio, for example. The driving torque ratio is set in a range of, for example, 4:6 to 6:4 depending on the desired driving performance. For example, when emphasis is placed on the driving stability of the vehicle 1, the target output torque of the first motor 11F is made larger than the target output torque of the second motor 11R. Also, for example, when emphasis is placed on the turning performance of the vehicle 1, the target output torque of the second motor 11R is made larger than the target output torque of the first motor 11F. The driving torque ratio may be variable depending on the driving state of the vehicle 1.

[0042] Furthermore, the target torque setting unit 61 determines whether to drive the first motor 11F and the second motor 11R only by the first stator coils 43Fa, 43Ra or the second stator coils 43Fb, 43Rb, or both, depending on the magnitude of the target output torque of each of the first motor 11F and the second motor 11R. This makes it possible to improve the driving efficiency caused by power loss due to the operation of switching elements, wiring resistance, etc.

[0043] For example, when the target output torque is smaller than a predetermined threshold, the target torque setting unit 61 determines that the first motor 11F and the second motor 11R are driven by only either the first stator coils 43Fa, 43Ra or the second stator coils 43Fb, 43Rb. In this case, the target torque setting unit 61 sets the target output torque of each of the first motor 11F and the second motor 11R to the target output torque by either the first stator coils 43Fa, 43Ra or the second stator coils 43Fb, 43Rb, and sets the target output torque of the other stator coil to zero.

[0044] On the other hand, when the target output torque is equal to or greater than a predetermined threshold, the target torque setting unit 61 determines that the first motor 11F and the second motor 11R are driven by both the first stator coils 43Fa and 43Ra and the second stator coils 43Fb and 43Rb, respectively. In this case, the target torque setting unit 61 sets half the target output torque of each of the first motor 11F and the second motor 11R to the target output torque of each of the first stator coils 43Fa and 43Ra or the second stator coils 43Fb and 43Rb.

[0045] The target torque setting unit 61 may constantly drive the first motor 11F and the second motor 11R by both the first stator coils 43Fa, 43Ra and the second stator coils 43Fb, 43Rb, respectively. In this case, the target torque setting unit 61 sets half the target output torque of each of the first motor 11F and the second motor 11R to the target output torque of each of the first stator coils 43Fa, 43Ra or the second stator coils 43Fb, 43Rb.

[0046] Furthermore, when the warm-up process of the battery 20 is stopped, the target torque setting unit 61 sets the target regenerative torques of the first motor 11F and the second motor 11R based on the required braking torque of the vehicle 1. The required braking torque is calculated based on the accelerator pedal operation amount and the vehicle speed during manual driving. Moreover, the required driving torque is calculated based on the required acceleration obtained by calculation during automatic driving.

[0047] The target torque setting unit 61 sets a preset regenerative torque ratio, for example, a ratio between the target regenerative torque of the first motor 11F and the target regenerative torque of the second motor 11R. The regenerative torque ratio is set to, for example, 6:4. The regenerative torque ratio may be variable depending on the driving state of the vehicle 1.

[0048] Furthermore, the target torque setting unit 61 determines whether the first motor 11F and the second motor 11R should regenerate using only the first stator coils 43Fa and 43Ra or the second stator coils 43Fb and 43Rb, or both, depending on the magnitude of the target regenerative torque of each of the first motor 11F and the second motor 11R. This makes it possible to increase the regenerative efficiency caused by power loss due to the operation of switching elements, wiring resistance, etc.

[0049] For example, when the target regenerative torque is smaller than a predetermined threshold, the target torque setting unit 61 determines that the first motor 11F and the second motor 11R are to be regenerated only by either the first stator coils 43Fa, 43Ra or the second stator coils 43Fb, 43Rb. In this case, the target torque setting unit 61 sets the target regenerative torque of each of the first motor 11F and the second motor 11R to the target regenerative torque by either the first stator coils 43Fa, 43Ra or the second stator coils 43Fb, 43Rb, and sets the target regenerative torque of the other stator coil to zero.

[0050] On the other hand, when the required regenerative torque is equal to or greater than a predetermined threshold, the target torque setting unit 61 determines that the first motor 11F and the second motor 11R are to be regenerated by both the first stator coils 43Fa and 43Ra and the second stator coils 43Fb and 43Rb, respectively. In this case, the target torque setting unit 61 sets half the target regenerative torque of each of the first motor 11F and the second motor 11R to the target regenerative torque of each of the first stator coils 43Fa and 43Ra or the second stator coils 43Fb and 43Rb.

[0051] The target torque setting unit 61 may always cause the first motor 11F and the second motor 11R to regenerate by both the first stator coils 43Fa, 43Ra and the second stator coils 43Fb, 43Rb, respectively. In this case, the target torque setting unit 61 sets a half of the target regenerative torque of each of the first motor 11F and the second motor 11R to the target regenerative torque of each of the first stator coils 43Fa, 43Ra or the second stator coils 43Fb, 43Rb.

[0052] (Motor control unit) The motor control unit 63 controls the driving of the first inverter unit 13F and the second inverter unit 13R, and controls the driving and regeneration of the first motor 11F and the second motor 11R. Specifically, the motor control unit 63 controls the driving of the first inverter unit 13F and the second inverter unit 13R based on the target output torque and the target regenerative torque set in the first stator coils 43Fa, 43Ra and the second stator coils 43Fb, 43Rb of the first motor 11F and the second motor 11R, respectively.

[0053] More specifically, the motor control unit 63 sets the drive duty ratios of the switching elements provided in the first inverter circuits 13Fa, 13Ra and the second inverter circuits 13Fb, 13Rb of the first inverter unit 13F and the second inverter unit 13R, respectively, and controls the operation of the switching elements. As a result, a drive torque equivalent to a target output torque is output from the first motor 11F and the second motor 11R. Alternatively, a braking torque equivalent to a target regenerative torque is generated by the first motor 11F and the second motor 11R.

[0054] (Cooling water circuit control unit) The coolant circuit control unit 65 controls the operation of the coolant circuit 30, and controls the circulation of the coolant in the coolant circulation passage 35. The coolant circuit control unit 65 acquires battery temperature information transmitted from the battery management unit 21, and when the battery temperature is equal to or higher than a predetermined cooling start threshold, starts the operation of the coolant pump 31, and circulates the coolant in the coolant circulation passage 35. This makes it possible to suppress an increase in the battery temperature and a decrease in the charge / discharge performance of the battery 20.

[0055] Furthermore, when a command to start driving the coolant circuit 30 is generated by the battery warm-up control unit 67 described later, the coolant circuit control unit 65 controls the driving of the coolant circuit 30 and controls the circulation of the coolant in the coolant circulation passage 35. This increases the battery temperature and improves the charging and discharging performance of the battery 20.

[0056] (Battery warm-up control unit) The battery warm-up control unit 67 executes control to warm up the battery 20 when the temperature of the battery 20 is low. In this embodiment, the battery warm-up control unit 67 drives the cooling water pump 31 to circulate the cooling water in the cooling water circulation passage 35. The battery warm-up control unit 67 also drives the first inverter circuits 13Fa, 13Ra and the second inverter circuits 13Fb, 13Rb of the first inverter unit 13F and the second inverter unit 13R, respectively, to apply rotational torques in the opposite directions to the rotors 41F, 41R of the first motor 11F and the second motor 11R. As a result, the first motor 11F and the second motor 11R generate heat, the cooling water is heated by heat exchange, and the battery 20 is warmed by the cooling water.

[0057] Taking the motor drive circuit shown in FIG. 2 as an example, the battery warm-up control unit 67 controls the drive of the first inverter unit 13F (second inverter unit 13R) so that the rotational torque given to the rotor 41F (41R) by the first stator coil 43Fa (43Ra) of the first motor 11F (second motor 11R) and the rotational torque given to the rotor 41F (41R) by the second stator coil 43Fb (43Rb) are in the opposite directions. As a result, the current value supplied to the first stator coil 43Fa (43Ra) and the second stator coil 43Fb (43Rb) of the first motor 11F (second motor 11R) increases by an amount corresponding to the offset of the rotational torque, and the energy loss of the offset rotational torque is consumed as heat energy. Therefore, the temperature of the first motor 11F (second motor 11R) is quickly increased and the coolant is efficiently heated, so that the battery 20 can be efficiently warmed.

[0058] The battery warm-up control unit 67 makes the sum of the rotational torque imparted to the rotor 41F (41R) by the first stator coil 43Fa (43Ra) and the rotational torque imparted to the rotor 41F (41R) by the second stator coil 43Fb (43Rb) coincide with the target output torque of the first motor 11F (second motor 11R). The target output torques of the first motor 11F and the second motor 11R are calculated by the same method as the calculation process by the target torque setting unit 61.

[0059] For example, when warming up the battery 20 before the vehicle 1 starts traveling after the motor control system 10 is started, the battery warm-up control unit 67 applies rotational torques of the same magnitude and in opposite directions to the rotor 41F (41R) to cause the first motor 11F (second motor 11R) to generate heat while maintaining the output torque of the first motor 11F (second motor 11R) at zero. In this case, the battery warm-up control unit 67 makes the sum of the rotational torque applied to the rotor 41F (41R) by the first stator coil 43Fa (43Ra) and the rotational torque applied to the rotor 41F (41R) by the second stator coil 43Fb (43Rb) zero. This makes it possible to warm up the battery 20 without generating a driving force for the vehicle 1.

[0060] On the other hand, after the vehicle 1 starts traveling, the battery warm-up control unit 67 makes the sum of the rotational torque given to the rotor 41F (41R) by the first stator coil 43Fa (43Ra) and the rotational torque given to the rotor 41F (41R) by the second stator coil 43Fb (43Rb) coincide with the target output torque of the first motor 11F (second motor 11R). This makes it possible to warm up the battery 20 while outputting a drive torque corresponding to the required drive torque of the vehicle 1. For example, the first stator coil 43Fa (43Ra) gives a constant reverse rotation torque to the rotor 41F (41R), and the second stator coil 43Fb (43Rb) gives the sum of a forward rotation torque that offsets the reverse rotation torque and a forward rotation torque corresponding to the target output torque. However, the method of setting the rotational torques applied to the rotor 41F (41R) by the first stator coil 43Fa (43Ra) and the second stator coil 43Fb (43Rb) is not limited to the above example.

[0061] The battery warm-up control unit 67 may switch the motor that generates heat at a predetermined timing while warming up the battery 20. The timing to switch the motor that generates heat may be determined based on, for example, the temperature of the motor, the elapsed time since the motor started to generate heat, or the amount of current supplied to the stator coil. By warming up the battery 20 while alternately switching the motor that generates heat, it is possible to continue warming up the battery 20 while preventing the temperature of each motor from exceeding a predetermined temperature.

[0062] Furthermore, after starting up the motor control system 10, the battery warm-up control unit 67 may repeatedly switch the motor to be heated and alternately heat up the first motor 11F and the second motor 11R before starting to output driving torque from the first motor 11F and the second motor 11R. By alternately switching the motor to be heated and increasing the temperature of the motor, the temperature difference between the motors at the time when the warm-up of the battery 20 is completed can be reduced. Therefore, it is possible to prevent the output performance of the first motor 11F and the second motor 11R from being changed due to the temperature difference between the motors.

[0063] Furthermore, when the battery warm-up control unit 67 causes the motors to generate heat by alternately switching between the motors to generate heat, the motors may be caused to generate heat in sequence, starting from the first motor 11F closest to the battery 20, toward the upstream side of the battery 20 in the circulation direction of the coolant circulating through the coolant circuit 30. This makes it possible to prevent the heat from being transferred to other devices before the coolant heated by the heat generated by the motors reaches the battery 20, thereby preventing a decrease in the cooling efficiency of the battery 20.

[0064] For example, when heat is generated from the second motor 11R, the heated coolant passes through the second inverter unit 13R, the first inverter unit 13F, the first motor 11F, and the radiator 33 before reaching the battery 20, and the heat of the coolant is released to the second inverter unit 13R, the first inverter unit 13F, the first motor 11F, and the radiator 33. On the other hand, when heat is generated from the first motor 11F, the heated coolant does not pass through the second inverter unit 13R, the first inverter unit 13F, and the first motor 11F, so the amount of heat release can be reduced.

[0065] Furthermore, when the rated output torques of the first motor 11F and the second motor 11R are different, the battery warm-up control unit 67 may cause the motors to generate heat in order from the motor with the largest rated output torque. The larger the rated output torque of the motor, the larger the torque that can be applied to the rotor 41F (41R) in the opposite directions to cancel each other out. Therefore, the larger the rated output torque of the motor, the larger the amount of heat that can be generated, and the faster the temperature of the cooling water can be raised.

[0066] The battery warm-up control unit 67 may acquire information on the temperature of the coolant output from the coolant temperature sensor 37 while the battery 20 is being warmed up, and when the temperature of the coolant reaches a predetermined upper threshold, stop the process of applying rotational torque in the opposite directions to the rotor 41F (41R). This keeps the temperature of the coolant supplied to the battery 20 below a predetermined temperature, and prevents damage to the battery 20 due to overheating.

[0067] Furthermore, the battery warm-up control unit 67 may execute a process of applying a rotational torque in the opposite directions to the rotor 41F (41R) when the output voltage of the battery 20 is equal to or higher than a predetermined threshold. This suppresses an increase in power consumption due to the process of applying a rotational torque in the opposite directions to the rotor 41F (41R) when the output voltage of the battery 20 is less than the threshold, and prevents a voltage drop in the battery 20.

[0068] <4. Processing operation example> So far, an example of the configuration of the motor control system 10 according to this embodiment has been described. Next, an example of the battery warm-up process operation by the control device 50 of the motor control system 10 will be described with reference to a flowchart.

[0069] 4 is a flowchart showing an example of a battery warm-up process operation by the control device 50 according to this embodiment. In the following, an example will be described in which the battery 20 is warmed up while switching the motor to be heated based on the temperatures of the first motor 11F and the second motor 11R.

[0070] First, when the drive system of the vehicle 1 is started (step S11), the battery warm-up control unit 67 of the processing unit 51 determines whether or not the battery 20 needs to be warmed up (step S13). Specifically, the battery warm-up control unit 67 acquires information on the battery temperature Tb transmitted from the battery management device 21, and determines that the battery 20 needs to be warmed up when the battery temperature Tb is less than a predetermined warm-up start threshold Tb_0. However, the method of determining whether or not the battery 20 needs to be warmed up is not limited to the above example. For example, the battery warm-up control unit 67 may determine whether or not the battery 20 needs to be warmed up based on the outside air temperature, or may determine whether or not the battery 20 needs to be warmed up based on the outside air temperature and the elapsed time since the motor control system 10 was stopped.

[0071] When it is determined that the battery 20 needs to be warmed up (S13 / No), the battery warm-up control unit 67 ends the warm-up control process for the battery 20. On the other hand, when it is determined that the battery 20 needs to be warmed up (S13 / Yes), the battery warm-up control unit 67 starts the coolant circuit 30 (step S15). Specifically, the battery warm-up control unit 67 generates a command to start the coolant circuit 30, and the coolant circuit control unit 65 starts driving the coolant pump 31. The driving amount of the coolant pump 31 may be constant, but may also be controlled based on the discharge pressure, discharge flow rate, etc.

[0072] Next, the battery warm-up control unit 67 judges whether the output voltage Vb of the battery 20 is equal to or higher than a predetermined threshold Vb_thr (step S17). Here, it is judged whether a process of applying rotational torques in mutually opposite directions to the rotors 41F, 41R (hereinafter also referred to as "reverse torque driving") can be executed without causing a voltage drop in the battery 20. The predetermined threshold Vb_thr may be determined according to a set value of the rotational torques to be offset by the reverse torque driving. In other words, the larger the set value of the rotational torques to be offset, the larger the output current of the battery 20 to be output in the reverse torque driving, and therefore the predetermined threshold Vb_thr is set to a large value.

[0073] If the output voltage Vb of the battery 20 is not equal to or greater than the predetermined threshold Vb_thr (S17 / No), the battery warm-up control unit 67 ends the warm-up control process for the battery 20. On the other hand, if the output voltage Vb of the battery 20 is equal to or greater than the predetermined threshold Vb_thr (S17 / Yes), the battery warm-up control unit 67 determines whether the coolant temperature Tw is less than a predetermined upper threshold Tw_thr (step S19). Here, it is determined whether the coolant temperature Tw is already in a high temperature state. The predetermined upper threshold Tw_thr may be determined according to the compensation temperature of the battery 20.

[0074] If the coolant temperature Tw is not less than the predetermined upper threshold Tw_thr (S19 / No), the battery warm-up control unit 67 ends the warm-up control process for the battery 20. This can prevent the battery 20 from being damaged due to overheating. On the other hand, if the coolant temperature Tw is less than the predetermined upper threshold Tw_thr (S19 / Yes), the battery warm-up control unit 67 determines whether the vehicle 1 is in a state before starting to run (step S21). For example, the battery warm-up control unit 67 may determine that the vehicle 1 is in a state before starting to run if the required drive torque calculated based on the accelerator opening or the required acceleration information is not a positive value exceeding zero after the motor control system 10 is started. However, the method of determining whether the vehicle 1 is in a state before starting to run is not limited to the above example.

[0075] When it is determined that the vehicle 1 is in a pre-traveling state (S21 / Yes), the battery warm-up control unit 67 executes pre-traveling warm-up processing (step S23). On the other hand, when it is not determined that the vehicle 1 is in a pre-traveling state (S21 / No), the battery warm-up control unit 67 executes post-traveling warm-up processing (step S25).

[0076] FIG. 5 is a flowchart showing an example of a pre-travel warm-up process. Before the vehicle 1 starts traveling, the first motor 11F and the second motor 11R are driven with a counter torque so that no driving torque is output from the first motor 11F and the second motor 11R.

[0077] The battery warm-up control unit 67 determines whether the temperature Tm1 of the first motor 11F is equal to or lower than a predetermined reference temperature Tm1_thr (step S31). Specifically, the battery warm-up control unit 67 acquires information on the temperature Tm1 of the first motor 11F output from the first motor temperature sensor 15F provided on the first motor 11F, and determines whether the temperature Tm1 of the first motor 11F is equal to or lower than a predetermined reference temperature Tm1_thr set in advance. The predetermined reference temperature Tm1_thr is set to an allowable temperature value in consideration of the internal resistance of the first motor 11F that depends on the temperature Tm1 of the first motor 11F, etc.

[0078] If the temperature Tm1 of the first motor 11F is equal to or lower than the predetermined reference temperature Tm1_thr (S31 / Yes), the battery warm-up control unit 67 drives the first motor 11F with a reverse torque (step S33). Specifically, the battery warm-up control unit 67 controls the driving of the first inverter circuit 13Fa and the second inverter circuit 13Fb of the first inverter unit 13F to apply rotational torques of the same magnitude and in the opposite directions to each other to the rotor 41F of the first motor 11F. As a result, the offset rotational torques are consumed as thermal energy, and the temperature of the first motor 11F rises. Then, the heat of the first motor 11F is transferred to the battery 20 via the coolant circulating in the coolant circuit 30, and the battery 20 is heated (warmed up).

[0079] On the other hand, if the temperature Tm1 of the first motor 11F is not equal to or lower than the predetermined reference temperature Tm1_thr (S31 / No), the battery warm-up control unit 67 judges whether or not the temperature Tm2 of the second motor 11R is equal to or lower than the predetermined reference temperature Tm2_thr (step S35). Specifically, the battery warm-up control unit 67 acquires information on the temperature Tm2 of the second motor 11R output from the second motor temperature sensor 15R provided on the second motor 11R, and judges whether or not the temperature Tm2 of the second motor 11R is equal to or lower than the predetermined reference temperature Tm2_thr set in advance. The predetermined reference temperature Tm2_thr is set to an allowable temperature value in consideration of the internal resistance of the second motor 11R that depends on the temperature Tm2 of the second motor 11R, etc. When the first motor 11F and the second motor 11R are the same motor, the reference temperatures Tm1_thr and Tm2_thr may be the same value.

[0080] If the temperature Tm2 of the second motor 11R is equal to or lower than the predetermined reference temperature Tm2_thr (S35 / Yes), the battery warm-up control unit 67 drives the second motor 11R with a reverse torque (step S37). Specifically, the battery warm-up control unit 67 controls the driving of the first inverter circuit 13Ra and the second inverter circuit 13Rb of the second inverter unit 13R to apply rotational torques of the same magnitude and in the opposite directions to each other to the rotor 41R of the second motor 11R. As a result, the offset rotational torques are consumed as thermal energy, and the temperature of the second motor 11R increases. Then, the heat of the second motor 11R is transferred to the battery 20 via the coolant circulating in the coolant circuit 30, and the battery 20 is heated (warmed up).

[0081] On the other hand, if the temperature Tm2 of the second motor 11R is not equal to or lower than the predetermined reference temperature Tm2_thr (S35 / No), in order to prevent the first motor 11F and the second motor 11R from overheating, the reverse torque driving is not executed for either the first motor 11F or the second motor 11R. Even in this case, the heat of the first motor 11F and the second motor 11R is transferred to the battery 20 via the cooling water circulating in the cooling water circuit 30, and the battery 20 is heated (warmed up).

[0082] As long as the vehicle 1 is in a state before starting to travel, the process shown in FIG. 5 is repeatedly executed for each predetermined process cycle. Therefore, when the reverse torque drive of the first motor 11F continues and the temperature Tm1 of the first motor 11F reaches a predetermined reference temperature Tm1_thr, the drive is switched to the reverse torque drive of the second motor 11R. When the reverse torque drive of the second motor 11R continues and the temperature Tm2 of the second motor 11R reaches a predetermined reference temperature Tm2_thr, the drive is switched to the reverse torque drive of the first motor 11F. While the first motor 11F is reverse torque driven, the temperature of the second motor 11R decreases, and while the second motor 11R is reverse torque driven, the temperature of the first motor 11F decreases.

[0083] As a result, before the vehicle 1 starts traveling, the first motor 11F and the second motor 11R are alternately driven with reverse torque, and the first motor 11F and the second motor 11R are alternately heated. This reduces the risk that either the first motor 11F or the second motor 11R will overheat, and prevents the difference between the temperature Tm1 of the first motor 11F and the temperature Tm2 of the second motor 11R from becoming significantly large.

[0084] Fig. 6 is an explanatory diagram showing temperature changes of the first motor 11F and the second motor 11R due to the pre-travel warm-up process. In the example shown in Fig. 6, the first motor 11F and the second motor 11R are the same motor with the same rated output torque, and the predetermined reference temperatures Tm1_thr, Tm2_thr are the same value Tm_thr. Furthermore, at the start of the motor control system 10, the first motor 11F and the second motor 11R are each at a temperature equivalent to the outside air temperature.

[0085] After starting up the motor control system 10, if it is determined that warming up of the battery 20 is necessary, first, the reverse torque driving of the first motor 11F is executed in the first period Pr1(m1). Although the reverse torque driving may be started from the second motor 11R, in this embodiment, the reverse torque driving is started from the first motor 11F, which is located closer to the battery 20 than the second motor 11R toward the upstream side of the flow of the cooling water from the battery 20. In the first period Pr(m1), the temperature Tm1 of the first motor 11F rises, and the heat of the first motor 11F is transferred to the battery 20 via the cooling water, and the battery 20 is heated.

[0086] When the temperature Tm1 of the first motor 11F reaches a predetermined reference temperature Tm_thr, the second motor 11R is driven with a reverse torque in the following second period Pr2(m2). In the second period Pr2(m2), the temperature Tm2 of the second motor 11R rises, and the heat of the second motor 11R, together with the heat of the first motor 11F, is transferred to the battery 20 via the cooling water, and the battery 20 is heated. In the second period Pr2(m2), the temperature Tm1 of the first motor 11F falls, but the rate at which the temperature Tm1 of the first motor 11F falls is slower than the rate at which the temperature Tm2 of the second motor 11R rises. Therefore, at the time when the temperature Tm2 of the second motor 11R reaches the predetermined reference temperature Tm_thr, the temperature Tm1 of the first motor 11F does not fall to the outside air temperature.

[0087] When the temperature Tm2 of the second motor 11R reaches a predetermined reference temperature Tm_thr, the first motor 11F is driven with a reverse torque in the following third period Pr3(m1). In the third period Pr3(m1), the temperature Tm1 of the first motor 11F rises again, and the heat of the first motor 11F together with the heat of the second motor 11R is transferred to the battery 20 via the cooling water, heating the battery 20. In the third period Pr3(m1), the temperature Tm2 of the second motor 11R falls, but the rate at which the temperature Tm2 of the second motor 11R falls is slower than the rate at which the temperature Tm1 of the first motor 11F rises.

[0088] When the temperature Tm1 of the first motor 11F reaches the predetermined reference temperature Tm_thr again, the second motor 11R is driven with reverse torque in the following fourth period Pr4(m2). In the fourth period Pr4(m2), the temperature Tm2 of the second motor 11R rises again, and the heat of the second motor 11R together with the heat of the first motor 11F is transferred to the battery 20 via the coolant, heating the battery 20.

[0089] In this way, by alternately generating heat from the first motor 11F and the second motor 11R to warm up the battery 20, the temperature Tm1 of the first motor 11F and the temperature Tm2 of the second motor 11R alternately rise, thereby reducing the temperature difference between the motors at the end of warming up the battery 20. Therefore, it is possible to prevent the output performance of the first motor 11F and the second motor 11R from being changed due to the temperature difference between the motors.

[0090] FIG. 7 is a flowchart showing an example of a warm-up process after starting running. After the vehicle 1 starts traveling, the first motor 11F and the second motor 11R are driven with counter torque so that the first motor 11F and the second motor 11R each output a driving torque equivalent to a target output torque.

[0091] The battery warm-up control unit 67 calculates the target output torque of each of the first motor 11F and the second motor 11R (step S41). Specifically, the battery warm-up control unit 67 sets the target output torque of each of the first motor 11F and the second motor 11R based on the required driving torque of the vehicle 1. The required driving torque is calculated based on the accelerator pedal operation amount and the vehicle speed during manual driving. Furthermore, the required driving torque is calculated based on the required acceleration obtained by calculation during automatic driving. Furthermore, the battery warm-up control unit 67 sets, for example, the ratio between the target output torque of the first motor 11F and the target output torque of the second motor 11R to a driving torque ratio set in advance. The driving torque ratio may be variable depending on the driving state of the vehicle 1. The target output torque may be calculated by the target torque setting unit 61, and the battery warm-up control unit 67 may acquire the calculation result.

[0092] Next, the battery warm-up control unit 67 determines whether the temperature Tm1 of the first motor 11F is equal to or lower than the predetermined reference temperature Tm1_thr (step S43), similar to the above-mentioned step S31. If the temperature Tm1 of the first motor 11F is equal to or lower than the predetermined reference temperature Tm1_thr (S43 / Yes), the battery warm-up control unit 67 drives the first motor 11F with a counter torque (step S45). In this case, the battery warm-up control unit 67 drives the first motor 11F with a counter torque so that the drive torque output from the first motor 11F becomes the target output torque.

[0093] Specifically, the battery warm-up control unit 67 makes the sum of the rotation torque given to the rotor 41F by the first stator coil 43Fa of the first motor 11F and the rotation torque given to the rotor 41F by the second stator coil 43Fb coincide with the target output torque of the first motor 11F. For example, the first stator coil 43Fa gives a certain reverse rotation torque to the rotor 41F, and the second stator coil 43Fb gives the sum of the forward rotation torque that cancels out the reverse rotation torque and the forward rotation torque that corresponds to the target output torque. However, the method of setting the rotation torques given to the rotor 41F by the first stator coil 43Fa and the second stator coil 43Fb is not limited to the above example. As a result, the rotation torques that are cancelled out are consumed as thermal energy, and the temperature of the first motor 11F rises. Then, the heat of the first motor 11F is transferred to the battery 20 via the coolant circulating in the coolant circuit 30, and the battery 20 is heated (warmed up).

[0094] On the other hand, if the temperature Tm1 of the first motor 11F is not equal to or lower than the predetermined reference temperature Tm1_thr (S43 / No), the battery warm-up control unit 67 judges whether or not the temperature Tm2 of the second motor 11R is equal to or lower than the predetermined reference temperature Tm2_thr, as in the above-mentioned step S35 (step S47). If the temperature Tm2 of the second motor 11R is equal to or lower than the predetermined reference temperature Tm2_thr (S47 / Yes), the battery warm-up control unit 67 drives the second motor 11R with a counter torque (step S49). In this case, the battery warm-up control unit 67 drives the second motor 11R with a counter torque so that the drive torque output from the second motor 11R becomes the target output torque. As a result, the offset rotation torque is consumed as heat energy, and the temperature of the second motor 11R rises. Then, the heat of the second motor 11R is transferred to the battery 20 via the coolant circulating through the coolant circuit 30, and the battery 20 is heated (warmed up).

[0095] On the other hand, if the temperature Tm2 of the second motor 11R is not equal to or lower than the predetermined reference temperature Tm2_thr (S47 / No), in order to prevent the first motor 11F and the second motor 11R from being in an overheated state, the reverse torque driving is not executed for either the first motor 11F or the second motor 11R. Even in this case, the heat of the first motor 11F and the second motor 11R is transferred to the battery 20 via the cooling water circulating in the cooling water circuit 30, and the battery 20 is heated (warmed up).

[0096] After the vehicle 1 starts traveling, the process shown in FIG. 6 is repeatedly executed for each predetermined processing cycle. Therefore, when the temperature Tm1 of the first motor 11F reaches a predetermined reference temperature Tm1_thr, the second motor 11R is switched to reverse torque driving. When the temperature Tm2 of the second motor 11R reaches a predetermined reference temperature Tm2_thr, the first motor 11F is switched to reverse torque driving. As a result, before the vehicle 1 starts traveling, the first motor 11F and the second motor 11R are alternately reverse torque driven, and the risk of either the first motor 11F or the second motor 11R becoming overheated can be reduced.

[0097] 7 is an example of executing reverse torque driving of the first motor 11F or the second motor 11R when the first motor 11F and the second motor 11R generate a driving torque for the vehicle 1 after the vehicle 1 starts traveling. However, the battery warm-up control unit 67 can also execute reverse torque driving of the first motor 11F or the second motor 11R when the first motor 11F and the second motor 11R generate a braking torque for the vehicle 1.

[0098] In this case, the battery warm-up control unit 67 calculates the target regenerative torques of the first motor 11F and the second motor 11R in accordance with the required deceleration in step S41 in Fig. 7. In addition, the battery warm-up control unit 67 drives the first motor 11F or the second motor 11R with a reverse torque so that the regenerative torque generated by the first motor 11F or the second motor 11R becomes the target regenerative torque in step S45 or step S49 in Fig. 7. As a result, even when the vehicle 1 is decelerating after the vehicle 1 starts traveling, the heat of the first motor 11F and the second motor 11R is transferred to the battery 20 via the coolant circulating in the coolant circuit 30, and the battery 20 is heated (warmed up).

[0099] Returning to FIG. 4, after executing the pre-travel warm-up process or the post-travel warm-up process, the battery warm-up control unit 67 acquires the temperature Tb of the battery 20 and determines whether the temperature Tb of the battery 20 has reached a predetermined end threshold Tb_1 (step S27). The predetermined end threshold Tb_1 is set to an arbitrary value in order to determine whether the warm-up of the battery 20 has been completed. If the temperature Tb of the battery 20 has not reached the predetermined end threshold Tb_1 (S27 / No), the battery warm-up control unit 67 returns to step S17 and repeatedly executes the processes of the above-mentioned steps. On the other hand, if the temperature Tb of the battery 20 has reached the predetermined end threshold Tb_1 (S27 / Yes), the battery warm-up control unit 67 ends the warm-up process of the battery 20.

[0100] As described above, the motor control system 10 according to this embodiment drives the first inverter circuit 13Fa (13Ra) and the second inverter circuit 13Fb (13Rb) connected to the first motor 11F and the second motor 11R, respectively, and applies rotational torques in opposite directions to the rotors 41F (41R) of the first motor 11F and the second motor 11R. As a result, the energy loss of the offset rotational torque is consumed as heat energy, and the first motor 11F and the second motor 11R are quickly heated. Then, the heat of the first motor 11F and the second motor 11R is transferred to the battery 20 via the coolant, and the battery 20 is heated. Therefore, the time required to warm up the battery 20 can be shortened.

[0101] Furthermore, in the motor control system 10 according to this embodiment, the coolant circuit 30 is also provided in the first inverter unit 13F and the second inverter unit 13R. Therefore, heat generated by the switching elements when driving the first inverter unit 13F and the second inverter unit 13R is also transferred to the battery 20 via the coolant. As the amount of rotational torque that is offset increases, the number of times that the switching elements are driven also increases, and the amount of heat generated by the first inverter unit 13F and the second inverter unit 13R also increases, so that the time required to warm up the battery 20 can be further shortened.

[0102] <5. Modifications> Although the motor control system according to the present embodiment has been described above, various modifications of the above embodiment are possible. Some of the modifications will be described below.

[0103] In the above embodiment, the timing to switch the motor that performs the reverse torque drive is determined based on whether or not the temperature of the motor has reached a predetermined reference temperature. However, instead of the temperature of the motor, it may be determined based on whether or not the time that has elapsed since the start of the reverse torque drive has reached a predetermined reference time. For example, the motor that performs the reverse torque drive may be switched every 30 to 120 seconds. The reference time is set in advance so that the temperature of each motor does not exceed the predetermined reference temperature before the warm-up of the battery is completed. This allows the battery to be warmed up by the heat generated by the motor without each motor becoming overheated, and the time required for warming up the battery can be shortened.

[0104] In addition, the timing to switch the motor that performs reverse torque driving is determined based on whether the temperature of the motor has reached a predetermined reference temperature, but instead of the motor temperature, it may be determined based on whether the integrated value of the current supplied to the motor since the start of reverse torque driving has reached a predetermined reference value. The reference value of the integrated value of the current supplied is set in advance so that the temperature of each motor does not exceed the predetermined reference temperature until warming up of the battery is completed. This makes it possible to warm up the battery by the heat generated by the motor without each motor becoming overheated, and shortens the time required to warm up the battery.

[0105] In addition, in the above embodiment, the coolant circulating through the coolant circuit always passes through the radiator, but the coolant circuit may be configured to be capable of switching the flow path of the coolant so that the coolant does not pass through the radiator.

[0106] FIG. 8 is an explanatory diagram showing the configuration of a motor control system 100 according to a modified example. The coolant circuit 110 of the motor control system 100 includes a bypass passage 39 that connects the upstream side and downstream side of the radiator 33, and a flow path switching device 38 that switches between a first state in which the coolant passes through the radiator 33 and a second state in which the coolant passes through the bypass passage 39. The flow path switching device 38 is driven by the control device 50 to switch between the first state and the second state. The flow path switching device 38 may be, for example, a three-way valve that is driven by energization to switch the flow path, but may have other configurations. For example, the flow path switching device 38 may be an opening / closing valve that is provided in the middle of the bypass passage 39 and opens and closes the bypass passage 39.

[0107] In the motor control system 100 according to the modified example, while executing the warm-up process of the battery 20, the control device 50 drives the flow path switching device 38 to set the second state in which the coolant does not pass through the radiator 33. As a result, the coolant that has passed through the first motor 11F, the second motor 11R, the first inverter unit 13F, and the second inverter unit 13R and is heated is supplied to the battery 20 without being cooled by the radiator 33. Therefore, the heating efficiency of the battery 20 is improved, and the time required to warm up the battery 20 can be further shortened.

[0108] In the above embodiment, a four-wheel drive vehicle having a first motor and a second motor for driving the front wheels is taken as an example, but the drive system of the electric vehicle is not limited to the above example. For example, the electric vehicle may be a two-wheel drive vehicle having two motors capable of independently driving the left and right wheels of the front or rear wheels.

[0109] The electric vehicle may be a two-wheel drive vehicle or a four-wheel drive vehicle equipped with a single motor that drives either the front wheels or the rear wheels, or both. In this case, the control device can warm up the battery by repeatedly starting and stopping the reverse torque drive of the single motor, thereby shortening the time required to warm up the battery.

[0110] Although the preferred embodiment of the present disclosure has been described in detail above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person having ordinary knowledge in the technical field to which the present disclosure belongs can conceive of various modified or amended examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure. [Explanation of symbols]

[0111] 1: vehicle, 10: motor control system, 11F: first motor, 11R: second motor, 13F: first inverter unit, 13Fa·13Ra: first inverter circuit, 13Fb·13Rb: second inverter circuit, 13R: second inverter unit, 15F: first motor temperature sensor, 15R: second motor temperature sensor, 20: battery, 21: battery management device, 30: cooling water circuit, 31: cooling water pump, 33: radiator, 35: cooling water circulation passage, 37: cooling water temperature sensor, 38: flow path switching device, 39: bypass passage, 41F·41R: rotor, 43Fa·43Ra: first stator coil, 43Fb·43Rb: second stator coil, 50: control device, 51: processing unit, 53: memory unit, 57: vehicle state sensor, 61: target torque setting unit, 63: motor control unit, 65: cooling water circuit control unit, 67: battery warm-up control unit

Claims

1. A motor control system for an electric vehicle includes a battery, a motor having a rotor and a stator, two inverter circuits connected to the stator and controlling the driving and regeneration of the motor, respectively, and a control device that controls the driving of the two inverter circuits, a plurality of the motors are provided, and the two inverter circuits are connected to the stators of the respective motors; a cooling water circuit having a cooling water pump and circulating through at least the battery and the motor; The control device includes: a process of driving the cooling water pump to circulate the cooling water and driving the two inverter circuits to apply rotational torques in opposite directions to each other to the rotor, thereby warming up the battery with the cooling water whose temperature is increased by heat generated by the motor; switching the motor that generates heat at a predetermined timing while the battery is being warmed up; Motor control system for electric vehicles.

2. The control device includes:

2. The motor control system for an electric vehicle according to claim 1, wherein a sum of rotational torques applied to said rotor in mutually opposite directions is made to coincide with a target output torque of said motor.

3. The control device includes:

2. The motor control system for an electric vehicle according to claim 1, wherein after startup of the motor control system, and before starting to output drive torque from the motor, rotational torques of the same magnitude and in opposite directions are applied to the rotors to cause the motor to generate heat while maintaining the output torque of the motor at zero, thereby warming up the battery.

4. The cooling water circuit includes: a radiator for cooling the cooling water; a bypass passage connecting the upstream side and the downstream side of the radiator; a flow path switching device that switches between a first state in which the cooling water passes through the radiator and a second state in which the cooling water passes through the bypass passage, The control device includes: warming up the battery by setting the flow path switching device in the second state; 2. The electric vehicle motor control system according to claim 1.

5. The control device includes: When the temperature of the motor that is generating heat reaches a predetermined reference temperature, the motor stops generating heat and the motor that generates heat is switched to another motor.

2. The electric vehicle motor control system according to claim 1.

6. The control device includes: when an elapsed time from when a rotation torque in the opposite directions is applied to the rotor of the motor that is generating heat reaches a predetermined reference time, the generation of heat from the motor is stopped and the motor that is generating heat is switched to another motor; 2. The electric vehicle motor control system according to claim 1.

7. The control device includes: when an amount of current supplied to the stator after a rotational torque in mutually opposite directions is applied to the rotor of the motor being heated reaches a predetermined reference value, the generation of heat from the motor is stopped and the motor being heated is switched to another motor; 2. The electric vehicle motor control system according to claim 1.

8. The control device includes: After the motor control system is started, and before output of drive torque from the plurality of motors is started, Repeatedly switching the motors to be heated, and alternately raising the temperatures of the plurality of motors.

2. The electric vehicle motor control system according to claim 1.

9. The control device includes: and heating the motor in a direction toward an upstream side of the battery in a circulation direction of the cooling water circulating through the cooling water circuit, starting from the motor closest to the battery.

2. The electric vehicle motor control system according to claim 1.

10. The control device includes: The motors with the largest rated output torque are heated in order.

2. The electric vehicle motor control system according to claim 1.

11. The control device includes: when the temperature of the cooling water circulating through the cooling water circuit reaches a predetermined upper threshold, the process of driving the two inverter circuits to apply rotational torques in opposite directions to each other to the rotor is stopped.

2. The electric vehicle motor control system according to claim 1.

12. An electric vehicle including a battery, a motor having a rotor and a stator, two inverter circuits connected to the stator and controlling the driving and regeneration of the motor, respectively, and a control device controlling the driving of the two inverter circuits, a plurality of the motors are provided, and the two inverter circuits are connected to the stators of the respective motors; a cooling water circuit having a cooling water pump and circulating through at least the battery and the motor; The control device includes: a process of driving the cooling water pump to circulate the cooling water and driving the two inverter circuits to apply rotational torques in opposite directions to each other to the rotor, thereby warming up the battery with the cooling water whose temperature is increased by heat generated by the motor; switching the motor that generates heat at a predetermined timing while the battery is being warmed up; Electric car.

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