Control method for electric vehicle and control system for electric vehicle

Abstract

The present invention is a control method for an electric vehicle, wherein: a first torque command value is output to a first motor for driving a first drive wheel; a second torque command value is output to a second motor for driving a second drive wheel different from the first drive wheel; and driving is performed by the first motor and the second motor receiving power supply from a battery. In the control method, when the temperature of the battery is lower than a predetermined first threshold temperature, a total torque command value obtained by adding the first torque command value and the second torque command value is output to the first motor, a three-phase short-circuit command for bringing the second motor into a three-phase short-circuit state is output to the second motor, a three-phase short-circuit torque generated in the second motor is estimated on the basis of a rotation state of the second motor, and the total torque command value is corrected on the basis of the three-phase short-circuit torque.

Description

Electric vehicle control method and electric vehicle control system

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

[0002] JP2015-116872A discloses a hybrid vehicle that runs on driving force generated by an engine or a motor, in which three-phase short-circuit control is performed on the motor to raise the temperature of the battery.

[0003] By executing three-phase short circuit control, a three-phase short circuit torque is generated in the motor. However, in JP2015-116872A, the three-phase short circuit torque generated during the three-phase short circuit control of the hybrid vehicle is supplemented by engine torque, making it difficult to improve torque accuracy and torque responsiveness during three-phase short circuit control.

[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control method for an electric vehicle and a control system for an electric vehicle that improves torque accuracy and torque responsiveness during three-phase short circuit control.

[0005] According to one aspect of the present invention, there is provided a control method for an electric vehicle in which a first torque command value is output to a first motor that drives first drive wheels and a second torque command value is output to a second motor that drives second drive wheels different from the first drive wheels, and the first motor and second motor are driven by power supplied from a battery. In this control method, when the temperature of the battery is lower than a predetermined first threshold temperature, a combined torque command value obtained by combining the first torque command value and the second torque command value is output to the first motor, a three-phase short-circuit command is output to the second motor to place the second motor in a three-phase short-circuit state, a three-phase short-circuit torque generated by the second motor is estimated based on the rotational state of the second motor, and the combined torque command value is corrected based on the three-phase short-circuit torque.

[0006] FIG. 1 is a diagram showing the main configuration of an electric vehicle to which the control system for an electric vehicle of this embodiment is applied. FIG. 2 is a diagram showing an example of the configuration of an electric unit. FIG. 3 is a diagram showing the configuration of the control system for an electric vehicle of this embodiment. FIG. 4 is a block diagram of a final torque calculator. FIG. 5 is a block diagram of a rear current control unit. FIG. 6 is a diagram showing the control flow of the control system for an electric vehicle of this embodiment. FIG. 7 is a diagram showing the relationship between the motor rotation speed and magnet temperature for three-phase short-circuit torque. FIG. 8 is a diagram showing the relationship between the motor rotation speed and magnet temperature for three-phase short-circuit current. FIG. 9 is a time chart of three-phase short-circuit execution determination performed by a modified three-phase short-circuit execution determiner. FIG. 10 is a block diagram of a modified front current control unit. FIG. 11 is a block diagram of a modified final torque calculator. FIG. 12 is a block diagram of a modified front current command generation unit. FIG. 13 is a time chart of d-axis discharge control performed by a modified front current command generation unit.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] [Electric vehicle 100] The electric vehicle 100 to be controlled includes a front electric unit 4F that drives the front wheels 8F, a rear electric unit 4R that drives the rear wheels 8R, a vehicle controller 1 (VCM) that controls the front electric unit 4F and the rear electric unit 4R, a battery 3, and a battery management system 2 (BMS), which are connected by a CAN (Controller Area Network).

[0009] The front electric unit 4F (front motor 43F (FIG. 2)) is connected to a drive shaft 7F that supports the front wheels 8F via a front reduction gear 5F and a differential gear 6F. Torque generated by the front electric unit 4F (front motor 43F) is transmitted to the front wheels 8F via the front reduction gear 5F, the differential gear 6F, and the drive shaft 7F.

[0010] The rear electric unit 4R (rear motor 43R (FIG. 2)) is connected to a drive shaft 7R that supports a rear wheel 8R via a rear reduction gear 5R and a differential gear 6R. Torque generated by the rear electric unit 4R (rear motor 43R) is transmitted to the rear wheel 8R via the rear reduction gear 5R, the differential gear 6R, and the drive shaft 7R.

[0011] In the following embodiments, the front electric unit 4F is disposed on the drive shaft 7F of the front wheels 8F, and the rear electric unit 4R is disposed on the drive shaft 7R of the rear wheels 8R, but any configuration including two or more electric units may be used, and the arrangement of the electric units may be different. Furthermore, multiple electric units may be disposed in parallel on the same axis of either the front or rear wheels.

[0012] The battery 3 supplies electric power to the front electric unit 4F and the rear electric unit 4R, and also charges the battery 3 when regenerated electric power is generated in the front electric unit 4F or the rear electric unit 4R.

[0013] Although not shown in the drawings, the electric vehicle 100 is provided with a refrigerant circulation path that circulates a refrigerant (cooling water) between the front electric unit 4F (front reduction gear 5F), the rear electric unit 4R (rear reduction gear 5R), and the battery 3. The refrigerant circulation path supplies exhaust heat generated in the front electric unit 4F or the rear electric unit 4R to the battery 3 via the refrigerant.

[0014] The battery management unit 2 (BMS) calculates the remaining battery capacity (SOC) based on the terminal voltage and charge / discharge current integration of the battery 3, which serves as the vehicle power source, and acquires the battery temperature using a temperature sensor 31 attached to the battery 3, and manages the charge / discharge current etc. according to the acquired temperature. It also outputs information such as the remaining battery capacity (SOC), battery temperature, and battery warm-up request to the vehicle controller 1 (VCM) via the CAN.

[0015] The vehicle controller 1 (VCM) receives information from the accelerator pedal sensor, brake pedal sensor, e-PKB switch, shift position signal, etc., and outputs the required torque, shift position, brake depression amount, and e-PKB switch signal to the front electric unit 4F and rear electric unit 4R.

[0016] [Electric Unit] Fig. 2 is a diagram showing an example of the configuration of the electric unit. The front electric unit 4F includes a front motor controller 41F (Fig. 3), a front inverter 42F, and a front motor 43F.

[0017] The rear electric unit 4R includes a rear motor controller 41R (FIG. 3), a rear inverter 42R, and a rear motor 43R.

[0018] The front inverter 42F and the rear inverter 42R are connected in parallel to the battery 3.

[0019] The front electric unit 4F and the rear electric unit 4R operate independently of each other. That is, the front electric unit 4F converts the DC voltage input from the battery 3 into a three-phase AC voltage and applies it to the front motor 43F to drive the front motor 43F. Similarly, the rear electric unit 4R converts the DC voltage input from the battery 3 into a three-phase AC voltage and applies it to the rear motor 43R to drive the rear motor 43R. Note that in the following embodiments, the front wheels 8F of the four-wheel drive electric vehicle are drive wheels and the rear wheels 8R are three-phase short-circuit wheels, but the front wheels 8F may also be three-phase short-circuit wheels and the rear wheels 8R may also be drive wheels.

[0020] 3 is a diagram showing the configuration of the control system for the electric vehicle 100 of this embodiment. The control system for the electric vehicle 100 of this embodiment is divided into a vehicle controller 1 (torque distributor 11, final torque calculator 12), a battery management unit 2 (battery warm-up determination unit 21), a front motor controller 41F (front current command generation unit 411F, front current control unit 412F, front PWM modulation control unit 413F), and a rear motor controller 41R (rear current command generation unit 411R, rear current control unit 412R, rear PWM modulation control unit 413R, three-phase short-circuit execution determiner 414, speed calculation unit 415, three-phase short-circuit torque estimator 416).

[0021] The torque distributor 11 distributes a driving force command to the front and rear wheels based on the accelerator operation of the driver. The torque distributor 11 distributes a front torque command value (Tmf*) for the front wheels and a rear torque command value (Tmr*) for the rear wheels based on the accelerator operation. ＊ ) is output.

[0022] When the temperature of the battery 3 falls below a predetermined threshold temperature (first threshold temperature), the battery warm-up determination unit 21 outputs a battery warm-up request (battery warm-up flag in the ON state (Fbw = 1)) to the final torque calculator 12, and when the temperature of the battery 3 becomes equal to or higher than the threshold temperature, the battery warm-up request is stopped (battery warm-up flag in the OFF state (Fbw = 0) is output to the final torque calculator 12).

[0023] When the battery warm-up flag is in the OFF state (Fbw=0), the final torque calculator 12 calculates the front torque command value (Tmf ＊ ) is used as the front final torque command value (Tmff ＊ ) to the front current command generating unit 411F, and the rear torque command value (Tmr ＊ ) is used as the rear final torque command value (Tmrf ＊ ) to the rear current command generating unit 411R.

[0024] When the battery warm-up flag is in the ON state (Fbw=1), the final torque calculator 12 calculates the front torque command value (Tmf ＊ ) and rear torque command value (Tmr ＊) (to be described later, the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc)) to the front final torque command value (Tmff ＊ ) to the front current command generating unit 411F.

[0025] The final torque calculator 12 outputs the battery warm-up flag (Fbw) as is to the three-phase short circuit execution determiner 414. Furthermore, when three-phase short circuit control is possible in the rear inverter 42R, the final torque calculator 12 outputs an on-state three-phase short circuit command flag (Fsc=1) to the rear current control unit 412R. Details of the final torque calculator 12 will be described later.

[0026] The front current command generating unit 411F generates the front final torque command value (Tmff ＊ ) and the rotation speed (ωf) of the front motor 43F (FIG. 12) are input to the current table 409F (FIG. 12) to obtain the d-axis current command value (idf) in the rotating coordinate system that maximizes the torque efficiency. ＊ ) and q-axis current command value (iqf ＊ ) is calculated.

[0027] The front current control unit 412F determines the d-axis current command value (idf ＊ ) and the d-axis current detection value (idf) of the front motor 43F. ＊ ) and calculates the q-axis current command value (iqf ＊ ) and the q-axis current detection value (iqf) of the front motor 43F, the q-axis voltage command value (vqf ＊ ) is calculated.

[0028] The front PWM modulation control unit 413F controls the d-axis voltage command value (vdf ＊ ), q-axis current detection value (iqf ＊ ), and a front PWM signal (D ＊ uuf, D ＊ ulf, D ＊ vuf, D ＊ vlf, D ＊ wuf, D ＊ wlf) and output it to the front inverter 42F.

[0029] The rear current command generating unit 411R generates the rear final torque command value (Tmrf ＊ ) and the rotation speed (ω) of the rear motor 43R (FIG. 3) are input into a current table (not shown) to obtain the d-axis current command value (idr ＊ ) and the q-axis current command value (iqr ＊ When the three-phase short circuit command flag (Fsc=1) in the ON state is input from the final torque calculator 12, the rear current command generator 411R calculates the d-axis current command value (idr ＊ ) and the q-axis current command value (iqr ＊ ) may be stopped.

[0030] The rear current control unit 412R determines the d-axis current command value (idr ＊ ) and the d-axis current detection value (idr) of the rear motor 43R, the d-axis voltage command value (vdr ＊ ) and calculates the q-axis current command value (iqr ＊ ) and the q-axis current detection value (iqr) of the rear motor 43R, the q-axis voltage command value (vqr ＊ ) is calculated.

[0031] When the three-phase short circuit command flag (Fsc=1) in the ON state is input from the final torque calculator 12, the rear current control unit 412R sets the d-axis voltage command value (vdr ＊ The rear current control unit 412R calculates the q-axis voltage command value (vqr*) and the q-axis voltage command value (vqr*). Details of the rear current control unit 412R will be described later.

[0032] The rear PWM modulation control unit 413R controls the d-axis voltage command value (vdr ＊ ), q-axis current detection value (irf ＊ ), and a rear PWM signal (D ＊ uur, D ＊ ulr, D ＊ vur, D ＊ vlr, D ＊ wur, D ＊ wlr) and output it to the rear inverter 42R.

[0033] The rear motor 43R is equipped with a resolver 417 that detects the rotational position of the rotor of the rear motor 43R, and a temperature sensor 418 that detects the temperature of the magnet in the rotor of the rear motor 43R.

[0034] The speed calculation unit 415 calculates the rotation speed (ω) (or electrical angular velocity) of the rear motor 43R (rotor) from the period of the ABZ pulses (up / down counter pulses A, B, and origin signal pulse Z) output from the resolver 417, and outputs this to the three-phase short-circuit implementation determiner 414 and the three-phase short-circuit torque estimator 416.

[0035] The three-phase short circuit execution determiner 414 receives a PM temperature indicating the temperature of the power module from a temperature sensor (not shown) attached to the rear inverter 42R (power module), and also receives the rotation speed (ω) of the rear motor 43R from a speed calculation unit 415. The three-phase short circuit execution determiner 414 also receives a battery warm-up flag (Fbw).

[0036] The three-phase short circuit implementation determiner 414 outputs an off three-phase short circuit implementation determination flag (Fscj = 0) when the battery warm-up flag (Fbw) is on (Fbw = 1) and, for example, the rotation speed (ω) is less than a predetermined rotation speed (e.g., 4000 rpm) or when the PM temperature is equal to or higher than a predetermined threshold temperature (second threshold temperature).

[0037] The three-phase short circuit execution determiner 414 outputs an ON three-phase short circuit execution determination flag (Fscj=1) when the battery warm-up flag (Fbw) is ON (Fbw=1), the rotation speed (ω) is equal to or higher than a predetermined rotation speed (e.g., 4000 rpm), and the PM temperature is lower than a predetermined threshold temperature (second threshold temperature). Details of the three-phase short circuit execution determination by the three-phase short circuit execution determiner 414 will be described later.

[0038] When the battery warm-up flag (Fbw) is in the OFF state (Fbw=0), the three-phase short-circuit execution determiner 414 outputs the OFF three-phase short-circuit execution determination flag (Fscj=0) regardless of the rotation speed (ω) and PM temperature.

[0039] The three-phase short-circuit torque estimator 416 receives as input the three-phase short-circuit execution determination flag (Fscj=), the rotation speed (ω) of the rear motor 43R, and the magnet temperature.

[0040] When the three-phase short circuit execution determination flag is in the on state (Fscj=1), the three-phase short circuit torque estimator 416 estimates the three-phase short circuit torque (Tsc) (negative value) generated in the rear motor 43R based on the rotation speed (ω) or the magnet temperature, and outputs the three-phase short circuit torque (Tsc) to the final torque calculator 12. The method of estimating the three-phase short circuit torque (Tsc) in the three-phase short circuit torque estimator 416 will be described later.

[0041] [Final Torque Calculator 12] Fig. 4 is a block diagram of the final torque calculator 12. The final torque calculator 12 includes an AND circuit 121, an adder 122, a subtractor 123, a comparator 124, a switch 125, and a switch 126. The final torque calculator 12 calculates a rear torque command value (Tmr ＊ ) is used as the rear final torque command value (Tmrf ＊ ) to the rear current command generating section 411R (FIG. 3).

[0042] The AND circuit 121 outputs an ON state determination signal (Fsc1 = 1) to the switch 125 when the battery warm-up flag is ON (Fbw = 1) and the three-phase short circuit implementation determination flag is ON (Fcsj = 1), and outputs an OFF state determination signal (Fsc1 = 0) to the switch 125 in all other cases.

[0043] The adder 122 calculates the front torque command value (Tmf ＊ ) and rear torque command value (Tmr ＊ ) is added together to calculate a value (total torque command value) and output to the subtractor 123.

[0044] The subtractor 123 subtracts the output of the adder 122 (total torque command value (Tmf ＊ +Tmr ＊ )) minus the three-phase short-circuit torque (negative value) (corrected total torque command value (Tmf ＊ +Tmr ＊ −Tsc)) is output to the switch 126.

[0045] The comparator 124 receives the maximum torque (Tmax) that the front motor 43F can tolerate and the output of the subtractor 123 (the corrected total torque command value (Tmf ＊ +Tmr ＊−Tsc) is input.

[0046] The comparator 124 calculates the output of the subtractor 123 (the corrected total torque command value (Tmf ＊ +Tmr ＊ If the torque (−Tsc) is lower than the maximum torque (Tmax), the output signal “1” is output to the switch 125 .

[0047] The comparator 124 calculates the output of the subtractor 123 (the corrected total torque command value (Tmf ＊ +Tmr ＊ If the torque (−Tsc) is equal to or greater than the maximum torque (Tmax), the output signal “0” is output to the switch 125 .

[0048] The switch 125 receives the determination signal (Fsc1) and the input signal "0", and also receives the output signal ("0" or "1").

[0049] When the output signal "1" is input from the comparator 124, the switch 125 selects the determination signal (Fsc1) and outputs it as a three-phase short circuit command flag (Fsc = 0 or 1) to the switch 126 and the rear current control unit 412R (FIG. 3). Therefore, when the battery warm-up flag (Fbw) and the three-phase short circuit execution determination flag (Fscj) are both in the on state (Fbw = 1, Fscj = 1) and the output of the subtractor 123 (the corrected total torque command value (Tmf ＊ +Tmr ＊ When the torque (Tsc) is lower than the maximum torque (Tmax), the three-phase short circuit command flag (Fsc) is turned on (Fsc=1), and otherwise is turned off (Fsc=0).

[0050] When the output signal "1" is input from the comparator 124, the switch 125 selects the input signal "0" and outputs this as a three-phase short circuit command flag (Fsc=0) to the switch 126 and the rear current control unit 412R (FIG. 3).

[0051] The switch 126 receives the front torque command value (Tmf ＊ ) and the output of the subtractor 123 (the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc) is input, and further, a three-phase short circuit command flag (Fsc) is input.

[0052] When the three-phase short circuit command flag (Fsc) is in the OFF state (Fsc=0), the switch 126 switches the front torque command value (Tmf ＊ ) is selected and used as the front final torque command value (Tmff ＊ ) to the front current command generating unit 411F.

[0053] When the three-phase short circuit command flag (Fsc) is in the on state (Fsc=1), the switch 126 selects the output of the subtractor 123 (the corrected total torque command value) and converts it into the front final torque command value (Tmff ＊ ) to the front current command generating unit 411F.

[0054] [Rear Current Control Unit 412R] Figure 5 is a block diagram of the rear current control unit 412R. The rear current control unit 412R includes a decoupling voltage table 401R, a low-pass filter 402R, a subtractor 403R, a subtractor 404R, a PI controller 405R, an adder 406R, an adder 407R, a switch 408R, and a switch 409R. The front current control unit 412F has a configuration similar to that of the rear current control unit 412R (see Figure 10), but the switch 408R and the switch 409R are omitted.

[0055] The non-interference voltage table 401R contains the d-axis current command value (idr ＊ ) and the q-axis current command value (iqr ＊ ) is input. The non-interference voltage table 401R is ＊ ) and the q-axis current command value (iqr ＊ ) to cancel out the interference voltage between the d-q orthogonal coordinate axes based on ＊ ＿ｄｃｐｌ ) and q-axis decoupling voltage (vqr ＊ ＿ｄｃｐｌ ) is calculated.

[0056] The low-pass filter 402R receives the d-axis decoupling voltage (vdr ＊ ＿ｄｃｐｌ ) and q-axis decoupling voltage (vqr ＊ ＿ｄｃｐｌ ) is input to the low-pass filter 402R. The low-pass filter 402R removes high-frequency components from the d-axis non-interference voltage (vdr ＊＿ｄｃｐｌ＿ｆｌｔ ) and q-axis decoupling voltage (vqr ＊ ＿ｄｃｐｌ＿ｆｌｔ ) to generate the

[0057] The subtractor 403R calculates the d-axis voltage command value (idr ＊ The difference is calculated by subtracting the d-axis voltage detection value (idr) of the rear motor 43R from the calculated value (idr), and is output to the PI controller 405R.

[0058] The subtractor 404R calculates the q-axis voltage command value (iqr ＊ The difference is calculated by subtracting the q-axis voltage detection value (iqr) of the rear motor 43R from the calculated value (iqr), and is output to the PI controller 405R.

[0059] The PI controller 405R multiplies the output of the subtractor 403R by a predetermined gain and then integrates it to obtain the d-axis FB voltage (vdr ＊ ｆｂ ) is calculated, and the output of the subtractor 404R is multiplied by the gain and integrated to obtain the q-axis FB voltage (vqr ＊ ｆｂ ) is calculated.

[0060] The adder 406R calculates the d-axis decoupling voltage (vdr ＊ ＿ｄｃｐｌ＿ｆｌｔ ) and d-axis FB voltage (vdr ＊ ｆｂ ) to obtain the d-axis voltage (Vdr1 ＊ ) is calculated, and the d-axis voltage (Vdr1 ＊ ) is output to the switch 408R.

[0061] The adder 407R calculates the q-axis non-interacting voltage (vqr ＊ ＿ｄｃｐｌ＿ｆｌｔ ) and q-axis FB voltage (vqr ＊ ｆｂ ) to obtain the q-axis voltage (vqr1 ＊ ) and calculate the q-axis voltage (vdr1 ＊ ) is output to the switch 409R.

[0062] The switch 408R receives the d-axis voltage (vdr1 ＊ ) and an input voltage of "0", and further a three-phase short circuit command flag (Fsc) is input.

[0063] When the three-phase short circuit command flag is in the OFF state (Fsc=0), the switch 408R switches the d-axis voltage (vdr1 ＊ ) is selected and used as the d-axis voltage command value (vdr ＊ ) to the front PWM modulation control section 413F (FIG. 3).

[0064] When the three-phase short circuit command flag is in the on state (Fsc=1), the switch 408R selects the input voltage "0" and sets it as the d-axis voltage command value (vdr ＊ ) to the front PWM modulation control section 413F (FIG. 3).

[0065] The switch 409R receives the q-axis voltage (vqr1 ＊ ) and an input voltage of "0", and further a three-phase short circuit command flag (Fsc) is input.

[0066] When the three-phase short circuit command flag is in the OFF state (Fsc=0), the switch 409R switches the q-axis voltage (vqr1 ＊ ) is selected and used as the q-axis voltage command value (vqr ＊ ) to the front PWM modulation control section 413F (FIG. 3).

[0067] When the three-phase short circuit command flag is in the on state (Fsc=1), the switch 409R selects the input voltage "0" and sets it as the q-axis voltage command value (vdr ＊ ) to the front PWM modulation control section 413F (FIG. 3).

[0068] Therefore, when the three-phase short circuit command flag is in the on state (Fsc=1), the rear current control unit 412R sets the d-axis voltage command value (vdr ＊ ) and the q-axis voltage command value (vqr ＊ ) are set to zero and output to the rear PWM modulation control section 413R. ＊ uur, D ＊ ulr, D ＊ vur, D ＊ vlr, D ＊ wur, D ＊ wlr), "D ＊ uur, D ＊ vur, D ＊ The switching element to which "wur" is input is fully open, and "D ＊ulr, D ＊ vlr, D ＊ The switching element to which "wlr" is input is fully closed, or "D ＊ uur, D ＊ vur, D ＊ The switching element to which "wur" is input is fully closed, and "D ＊ ulr, D ＊ vlr, D ＊ The switching element to which "wlr" is input is fully open.

[0069] 6 is a diagram showing a control flow of the control system of the electric vehicle 100 of this embodiment. In step S601, the vehicle controller 1 (final torque calculator 12) determines whether or not there is a battery warm-up request from the battery management unit 2 (whether the battery warm-up flag (Fbw) is on (Fbw=1) or off (Fbw=0)), and if the determination is YES, the process proceeds to step S602, and if the determination is NO, the process proceeds to step S606.

[0070] In step S602, the vehicle controller 1 (final torque calculator 12) determines whether or not three-phase short-circuit control is possible (whether the three-phase short-circuit implementation determination flag (Fscj) is on (Fscj = 1) or off (Fscj = 0)), and if YES, proceeds to step S603, and if NO, proceeds to step S606.

[0071] In step S603, the vehicle controller 1 (final torque calculator 12) calculates the total torque command value (Tmf ＊ +Tmr ＊ ) and corrects the combined torque command value by the three-phase short-circuit torque (Tsc) to obtain a corrected combined torque command value (Tmf ＊ +Tmr ＊ -Tsc) is calculated.

[0072] In step S604, the vehicle controller 1 (final torque calculator 12) calculates the corrected total torque command value (Tmf ＊ +Tmr ＊If the result is NO, the process proceeds to step S605, and if the result is NO, the process proceeds to step S606.

[0073] In step S605, the vehicle controller 1 (final torque calculator 12) sets the three-phase short circuit command flag to the on state (Fsc=1) and executes three-phase short circuit control on the rear inverter 42R and the rear motor 43R.

[0074] In step S606, the vehicle controller 1 (final torque calculator 12) sets the three-phase short circuit command flag to the off state (Fsc = 0), prohibits three-phase short circuit control for the rear inverter 42R and the rear motor 43R, and stops the three-phase short circuit control if it is already being performed.

[0075] [Three-phase short-circuit torque estimator 416] The following describes the calculation for estimating the three-phase short-circuit torque in the three-phase short-circuit torque estimator 416. Generally, the dq-axis voltage equation of a three-phase Y-connection synchronous motor can be expressed as the following equation (1). where R: winding resistance Ld: d-axis inductance Lq: q-axis inductance φa: magnet magnetic flux ω: motor rotation speed

[0076] By solving equation (1) for id and iq, the following equation (2) can be derived.

[0077] However, Gn(s) in equation (2) satisfies the relationship of the following equation (3).

[0078] From equations (2) and (3), in three-phase short-circuit control in which vd and vq are controlled to 0, the following equations (4) and (5) hold.

[0079] Generally, the torque generated by a three-phase Y-connection synchronous motor can be calculated from id and iq using the following equation (6). where p: number of pole pairs

[0080] From equations (4), (5), and (6), it can be seen that the three-phase short-circuit torque (Tsc) generated during three-phase short-circuit control is uniquely determined by the motor rotation speed, winding resistance, and magnet magnetic flux.

[0081] FIG. 7 is a diagram showing the relationship between the motor rotation speed (ω) and the magnet temperature in relation to the three-phase short-circuit torque (Tsc).

[0082] As shown in FIG. 7 , the three-phase short-circuit torque (Tsc) was measured when the magnet temperature was −40° C., 60° C., and 160° C. In each case, as the rotation speed (ω) was increased from zero, the torque monotonically decreased, reaching a minimum value at a predetermined rotation speed where the absolute value was maximized, and then as the rotation speed was further increased, the torque monotonically increased, converging to become a substantially constant and minute deceleration torque.

[0083] The three-phase short-circuit torque (Tsc) reaches a minimum value when the magnet temperature is -40°C and the rotation speed is approximately 200 rpm, when the magnet temperature is 60°C and the rotation speed is approximately 250 rpm, and when the magnet temperature is 160°C and the rotation speed is approximately 450 rpm, and the minimum value decreases as the temperature rises. Furthermore, in the rotation speed range where the three-phase short-circuit torque (Tsc) reaches a minimum value, the three-phase short-circuit torque (Tsc) changes significantly with changes in magnet temperature.

[0084] On the other hand, in an operating region where the rotation speed is sufficiently larger than the rotation speed at which the three-phase short-circuit torque (Tsc) reaches its minimum value (for example, a region of 4000 rpm or more), the change in the three-phase short-circuit torque (Tsc) due to magnet temperature is small.

[0085] Therefore, if three-phase short-circuit control is performed in the above operating region, the three-phase short-circuit torque (Tsc) can be estimated independently of the magnet temperature.

[0086] Therefore, a one-dimensional lookup table is created in advance that represents the relationship between the rotation speed and the three-phase short-circuit torque (Tsc) in the above operating range of the rear motor 43R. The three-phase short-circuit torque estimator 416 can then easily estimate the three-phase short-circuit torque (Tsc) by applying the input rotation speed (ω) to the one-dimensional lookup table.

[0087] In this embodiment, a two-dimensional lookup table showing the relationship between the three-phase short-circuit torque (Tsc), the magnet temperature, and the rotational speed (ω) is created in advance. The three-phase short-circuit torque estimator 416 may then estimate the three-phase short-circuit torque (Tsc) by applying the input rotational speed (ω) and magnet temperature to the two-dimensional lookup table. This makes it possible to expand the operating range in which battery temperature control by three-phase short-circuit control is possible (for example, the range in which the rotational speed (ω) is 4000 rpm or less), maximizing the effect. Furthermore, the estimation accuracy of the three-phase short-circuit torque (Tsc) can be improved.

[0088] [Determination of Three-Phase Short Circuit Implementation by Three-Phase Short Circuit Implementation Determinator 414] Figure 8 is a diagram showing the relationship between the motor rotation speed (ω) and magnet temperature for the three-phase short circuit current. As shown in Figure 8, the three-phase short circuit current rises sharply as the motor rotation speed (ω) increases from zero, and converges to a predetermined upper limit current according to the motor magnet temperature (-40°C, 60°C, 160°C in Figure 8).

[0089] As described above, the three-phase short circuit execution determiner 414 (FIG. 3) determines whether or not three-phase short circuit control can be executed when the battery warm-up flag is in the on state (Fbw=1).

[0090] During three-phase short circuit control, a large current continues to circulate between the inverter and the motor. For this reason, the three-phase short circuit execution determiner 414 (FIG. 3) monitors the PM temperature of the inverter (rear inverter 42R in this embodiment), and when it reaches a predetermined threshold temperature (second threshold temperature (hysteresis setting), for example, 120°C), it sets the three-phase short circuit execution determination flag to the OFF state (Fscj=0) and stops the three-phase short circuit control. When it falls below the predetermined threshold temperature (second threshold temperature (hysteresis setting), for example, 80°C), it sets the three-phase short circuit execution determination flag to the ON state (Fscj=1) and resumes the three-phase short circuit control. While the three-phase short circuit control is stopped, the rear final torque command value (Tmrf ＊ ) is used to execute current control for the rear motor 43R.

[0091] 9 is a time chart of a three-phase short circuit implementation determination performed by a modified example of the three-phase short circuit implementation determiner 414. The basic three-phase short circuit implementation determiner 414 (FIG. 3) sets the three-phase short circuit implementation determination flag to the OFF state (Fscj=0) when the PM temperature reaches a predetermined threshold temperature (second threshold temperature) under the condition that the rotation speed (ω) of the rear motor 43R is equal to or greater than a predetermined rotation speed (for example, 4000 rpm), and then sets the three-phase short circuit implementation determination flag to the ON state (Fscj=1) when the PM temperature falls below the threshold temperature (second threshold temperature).

[0092] On the other hand, in the modified example, the three-phase short-circuit implementation determination flag is alternately set to the ON state (Fscj=1) and the OFF state (Fscj=0) by time control.

[0093] More specifically, the three-phase short circuit implementation determiner 414 includes a first counter (not shown) that sets the three-phase short circuit implementation determination flag to an on state (Fscj = 1), and a second counter (not shown) that sets the three-phase short circuit implementation determination flag to an off state (Fscj = 0).

[0094] The first counter and the second counter count up at predetermined time intervals.

[0095] The first counter counts up from an initial value (e.g., zero) to a predetermined first full count value (FC1), and when the count value reaches the first full count value (FC1), it outputs a signal to the second counter to prompt it to count up and resets the count value. Here, the time it takes for the first counter to count up from zero to the first full count value (FC1) is defined as T1 (FIG. 9).

[0096] The second counter counts up from an initial value (e.g., zero) to a predetermined second full count value (FC2), and when the count value reaches the second full count value (FC2), it outputs a signal to the first counter to prompt it to count up and resets the count value. Here, the time it takes for the second counter to count up from zero to the second full count value (FC2) is defined as T2 (FIG. 9).

[0097] As shown in FIG. 9 , when the battery warm-up flag switches from the off state (Fbw=0) to the on state (Fbw=1) at time t0, the three-phase short-circuit implementation determiner 414 drives the first counter (or the second counter) to count up the first counter, sets the three-phase short-circuit implementation determination flag to the on state (Fscj=1) while the counter value of the first counter is lower than the first full count, and when the count value of the first counter reaches the first full count value, sets the three-phase short-circuit implementation determination flag to the off state (Fscj=0), outputs a signal to the second counter to prompt it to count up, and resets the count value of the first counter.

[0098] The second counter counts up when it receives the signal, and maintains the three-phase short-circuit implementation determination flag in the off state (Fscj = 0) while the count value of the second counter is lower than the second full count value. When the count value of the second counter reaches the second full count value, the second counter sets the three-phase short-circuit implementation determination flag to the on state (Fscj = 1), outputs a signal to the first counter to prompt it to count up, and resets the count value of the second counter.

[0099] Therefore, when the battery warm-up flag is on (Fbw = 1), the three-phase short-circuit implementation determiner 414 alternately counts up the first counter and the second counter, and alternates between the on state (Fscj = 1) and the off state (Fscj = 0) of the three-phase short-circuit implementation determination flag at times T1 and T2, respectively.

[0100] Then, at time t1, when the battery warm-up flag is turned off (Fbw = 0), the three-phase short-circuit implementation determination flag is set to the off state (Fscj = 0) regardless of the states of the first counter and the second counter, the count-up of the counters (first counter, second counter) that are currently counting up is stopped, and the count values ​​are reset.

[0101] The first full count value (FC1) (T1) and the second full count value (FC2) (T2) may be the same value or may be set to different values, and may be dynamically changed depending on peripheral conditions.

[0102] As described above, the processing load can be reduced by alternately setting the three-phase short circuit implementation determination flag to the on state (Fscj=1) and the off state (Fscj=0) in the first counter and the second counter. Furthermore, excellent redundancy is achieved because control can be performed as intended even if the temperature sensor that detects the PM temperature fails.

[0103] [Modification of Front Current Control Section 412F] Fig. 10 is a block diagram of a modification of the front current control section 412F. Fig. 11 is a time chart of the d-axis discharge control executed by the modification of the front current control section 412F.

[0104] The front current control unit 412F includes a decoupling voltage table 401F, a low-pass filter 402F, a subtractor 403F, a subtractor 404F, a PI controller 405F, an adder 406F, an adder 407F, and a low-pass filter 408F.

[0105] The non-interference voltage table 401F contains the d-axis current command value (idf ＊ ) and q-axis current command value (iqf ＊ ) is input. The non-interference voltage table 401F is a d-axis current command value (idf ＊ ) and q-axis current command value (iqf ＊ ) to cancel out the interference voltage between the d-q orthogonal coordinate axes based on ＊ ＿ｄｃｐｌ ) and q-axis decoupling voltage (vqf ＊ ＿ｄｃｐｌ ) is calculated.

[0106] The low-pass filter 402F receives the d-axis decoupling voltage (vdf ＊ ＿ｄｃｐｌ ) and q-axis decoupling voltage (vqf ＊ ＿ｄｃｐｌ ) is input to the low-pass filter 402F. The low-pass filter 402F removes high-frequency components from the d-axis non-interacting voltage (vdf ＊ ＿ｄｃｐｌ＿ｆｌｔ ) and q-axis decoupling voltage (vqf ＊ ＿ｄｃｐｌ＿ｆｌｔ ) to generate the

[0107] The subtractor 403F calculates the d-axis voltage command value (idf ＊The difference obtained by subtracting the d-axis voltage detection value (idf) of the front motor 43F from the calculated value (idf) is calculated and output to the PI controller 405F.

[0108] The subtractor 404F calculates the q-axis voltage command value (iqf ＊ The difference is calculated by subtracting the q-axis voltage detection value (iqf) of the front motor 43F from the calculated value (iqf), and is output to the PI controller 405F.

[0109] The PI controller 405F multiplies the output of the subtractor 403F by a predetermined gain and then integrates it to obtain the d-axis FB voltage (vdf ＊ ｆｂ ) is calculated, and the output of the subtractor 404F is multiplied by the gain and integrated to obtain the q-axis FB voltage (vqf ＊ ｆｂ ) is calculated.

[0110] The adder 406F calculates the d-axis decoupling voltage (vdf ＊ ＿ｄｃｐｌ＿ｆｌｔ ) and d-axis FB voltage (vdf ＊ ｆｂ ) to obtain the d-axis voltage (vdf1 ＊ ) and calculate the d-axis voltage (vdf1 ＊ ) is output to low pass filter 408F.

[0111] The adder 407F calculates the q-axis non-interacting voltage (vqf ＊ ＿ｄｃｐｌ＿ｆｌｔ ) and q-axis FB voltage (vqf ＊ ｆｂ ) to obtain the q-axis voltage (vqf1 ＊ ) and calculate the q-axis voltage (vdf1 ＊ ) is output to low pass filter 408F.

[0112] The low-pass filter 408F calculates the filtered d-axis voltage (vdf1 ＊ ＿ｆｌｔ ), and the filtered q-axis voltage (vqf1 ＊ ＿ｆｌｔ ) is calculated.

[0113] Incidentally, the front final torque command value (Tmff＊ When the three-phase short circuit command control flag is switched from the OFF state (Fsc=0) to the ON state (Fsc=1), the first torque command value (Tmf ＊ ) to the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc), and the d-axis voltage command value (vdf ＊ ) and the q-axis voltage command value (vqf ＊ ) also switches instantly.

[0114] On the other hand, when the driving state of the rear inverter 42R (rear motor 43R) is a three-phase driving state (first state), it takes a predetermined time from when the three-phase short circuit control command flag switches from the off state (Fsc = 0) to the on state (Fsc = 1) until the driving state of the rear inverter 42R (rear motor 43R) transitions from the three-phase driving state to the three-phase short circuit state.

[0115] Therefore, before the rear inverter 42R (rear motor 43R) switches to the three-phase short-circuit state, the operating state of the front inverter 42F (front motor 43F) changes, causing torque fluctuations and giving the driver a sense of discomfort.

[0116] Therefore, in the modified example, the front motor 43F (front inverter 42F) is set to the first torque command value (Tmf ＊ ) to the first state in which the motor is driven based on the corrected total torque command value (Tmf ＊ +Tmr ＊ The output of the adder 406F and the output of the adder 407F are filtered by a low-pass filter 408F so as not to immediately transition to the second state in which the output is driven based on the output voltage (−Tsc).

[0117] Then, in the low-pass filter 408F, the time constants (τ) of equations (7) and (8) are set corresponding to the predetermined time. As a result, the operating state of the front inverter 42F (front motor 43F) is changed from the first state to the second state in accordance with the transition time when the rear inverter 42R (rear motor 43R) changes from the three-phase drive state (first state) to the three-phase short-circuit state (second state), thereby suppressing torque fluctuations and reducing the sense of discomfort felt by the driver. Similarly, the operating state of the front inverter 42F (front motor 43F) is changed from the second state to the first state in accordance with the transition time when the rear inverter 42R (rear motor 43R) changes from the three-phase short-circuit state (second state) to the three-phase drive state (first state), thereby suppressing torque fluctuations and reducing the sense of discomfort felt by the driver.

[0118] The low-pass filter 408F outputs the filtered d-axis voltage (vdf1 ＊ ＿ｆｌｔ ) is output as it is to the front PWM modulation control unit 413F (FIG. 3) as the d-axis voltage command value, and the filtered q-axis voltage (vqf1 ＊ ＿ｆｌｔ ) is used as the q-axis voltage command value (vqf ＊ ) to the front PWM modulation control section 413F (FIG. 3).

[0119] 11 is a block diagram of a modified final torque calculator 12. The modified final torque calculator 12 has the AND circuit 121, the comparator 124, and the switch 125 of the final torque calculator 12 in the basic form (FIG. 4), and further has a subtractor 127, an adder 128, a switch 129, a low-pass filter 130, and an adder 131. The modified final torque calculator 12 has a purpose similar to that of the modified front current control unit 412F.

[0120] The subtractor 127 calculates the rear torque command value (Tmr ＊ The value obtained by subtracting the three-phase short-circuit torque (negative value) from the torque saturation torque (saturation torque) is output to the adder 128.

[0121] The adder 128 subtracts the output of the subtracter 127 from the front torque command value (Tmf ＊ ) and the corrected total torque command value (Tmf＊ +Tmr ＊ −Tsc) is calculated and output to the comparator 124.

[0122] The switch 129 receives the input torque "0" and the output of the subtractor 127 (Tmr ＊ -Tsc) and further a three-phase short circuit control flag (Fsc) are input.

[0123] When the three-phase short circuit control flag is in the OFF state (Fsc=0), the switch 129 selects the input torque “0” and outputs it to the low-pass filter 130 .

[0124] When the three-phase short circuit control flag is in the ON state (Fsc=1), the switch 129 outputs the output (Tmr ＊ −Tsc) and outputs it to the low-pass filter 130.

[0125] The low-pass filter 130 is a filter having the same time constant (τ) as the low-pass filter 408 F, and outputs a filtered value to an adder 131 .

[0126] The adder 131 calculates the front torque command value (Tmf ＊ ) and the output of the low-pass filter 130 are added together to obtain the front final torque command value (Tmff ＊ ) to the front current command generating unit 411F (FIG. 3).

[0127] In the above configuration, when the three-phase short circuit control flag is in the OFF state (Fsc=0), the switch 129 selects the input torque "0", so the front final torque command value (Tmff ＊ ) is the front torque command value (Tmf ＊ ) is the same value.

[0128] On the other hand, when the three-phase short circuit control flag is in the ON state (Fsc=1), the switch 129 outputs the output (Tmr ＊ -Tsc), the front final torque command value (Tmff ＊ ) is the corrected total torque command value (Tmf ＊ +Tmr ＊ −Tsc).

[0129] When the three-phase short circuit control flag is switched from the OFF state (Fsc=0) to the ON state (Fsc=1), the switch 129 outputs the output (Tmr ＊ -Tsc), the output of the low-pass filter 130 is a first-order response due to the time constant (τ). ＊ ) is the front torque command value (Tmf ＊ ) to the corrected total torque command value (Tmf ＊ +Tmr ＊ −Tsc) with a time constant (τ).

[0130] This allows the operating state of the front inverter 42F (front motor 43F) to be changed from the first state to the second state in accordance with the transition time when the rear inverter 42R (rear motor 43R) changes from a three-phase drive state (first state) to a three-phase short-circuit state (second state), thereby suppressing torque fluctuations and reducing the driver's discomfort.

[0131] Conversely, when the three-phase short circuit control flag is switched from the ON state (Fsc=1) to the OFF state (Fsc=0), the switch 129 selects the input torque "0" as described above. In this case, the output of the low-pass filter 130 also becomes a first-order response due to the time constant (τ). Therefore, the final torque command value (Tmff ＊ ) is the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc) to the front torque command value (Tmf ＊ ) with a time constant (τ).

[0132] This allows the operating state of the front inverter 42F (front motor 43F) to be changed from the second state to the first state in accordance with the transition time when the rear inverter 42R (rear motor 43R) changes from a three-phase short-circuit state (second state) to a three-phase drive state (first state), thereby suppressing torque fluctuations and reducing the driver's discomfort.

[0133] [Modification of Front Current Command Generator 411F] Fig. 12 is a block diagram of a modification of the front current command generator 411F. Fig. 13 is a time chart of the d-axis discharge control executed by the modification of the front current command generator 411F.

[0134] As shown in FIG. 12, a front current command generating section 411F of the modified example includes a current table 409F, a switch 410F, a switch 414F, and an adder 415F.

[0135] The current table 409F contains the front final torque command value (Tmff ＊ ) and the rotation speed (ωf) of the front motor 43F are input.

[0136] The current table 409F is a front final torque command value (Tmff ＊ ) and the rotation speed (ωf) of the front motor 43F, the d-axis current value (idf1) (negative value) and the q-axis current value (iqf1) that maximize the torque efficiency are output. ＊ ) to the front current control section 412F (FIG. 3).

[0137] The switch 410F receives the input current "0" and the addition value (idf2) (negative value) for d-axis discharge control, as well as the three-phase short circuit control flag (Fsc).

[0138] When the three-phase short circuit control flag is in the on state (Fsc=1), the switch 410F selects the input current "0" and outputs it to the switch 414F.

[0139] When the three-phase short circuit control flag is in the OFF state (Fsc=0), the switch 410F selects the addition value (idf2) and outputs it to the switch 414F.

[0140] The switch 414F receives the input current "0" and the output of the switch 410F, and also receives the battery warm-up flag (Fbw).

[0141] When the battery warm-up flag is in the OFF state (Fbw=0), the switch 414F selects the input current "0" and outputs it to the adder 415F.

[0142] When the battery warm-up flag is in the on state (Fbw=1), the switch 414F selects the output of the switch 410F and outputs it to the adder 415F.

[0143] The adder 415F adds the d-axis current value (idf1) and the output of the switch 414F, and outputs the sum as a d-axis current command value (idf ＊ ) to the front current control section 412F (FIG. 3).

[0144] In the above configuration, when the battery warm-up flag is on (Fbw=1) and the three-phase short circuit control flag is off (Fsc=0), the adder 415F adds the d-axis current value (idf1) and the addition value (idf2), and calculates this as the d-axis current command value (idf ＊ ) to the front current control unit 412F (FIG. 3). In other cases, the adder 415F outputs the d-axis current value (idf1) as it is to the d-axis current command value (idf ＊ ) to the front current control section 412F (FIG. 3).

[0145] As shown in FIG. 13, when the battery warm-up flag is on (Fbw=1) and the three-phase short circuit control flag is on (Fsc=1), the d-axis discharge control is set to the off state, and when the battery warm-up flag is on (Fbw=1) and the three-phase short circuit control flag is off (Fsc=0), the d-axis discharge control is set to the on state (the state where the additional value (idf2) is added to the d-axis current command value (d-axis current value (idf1)) (idf ＊ As a result, when three-phase short circuit control cannot be performed even if there is a battery warm-up request, the d-axis discharge control is used to heat the front inverter 42F (front motor 43F), thereby improving the heating efficiency of the refrigerant (refrigerant circulation path) that heats the battery 3.

[0146] In addition, the switch 410F may be configured to select an input current of "0" when the three-phase short circuit control flag is in the off state (Fsc = 0), and to select an additional value (idf2) when the three-phase short circuit control flag is in the on state (Fsc = 1).

[0147] In this case, when the battery warm-up flag is on (Fbw=1) and the three-phase short circuit control flag is on (Fsc=1), the d-axis discharge control is turned on (the state (idf1) in which the additional value (idf2) is added to the d-axis current command value (d-axis current value (idf1))). ＊ = idf1 + idf2), and when the battery warm-up flag is on (Fbw = 1) and the three-phase short circuit control flag is off (Fsc = 0), the d-axis discharge control is set to the off state. As a result, the d-axis discharge control is executed when the three-phase short circuit control is executed, which improves the heating efficiency of the refrigerant (refrigerant circulation path) that heats the battery 3, and further reduces the load on the rear inverter 42R (rear motor 43R) that is in a three-phase short circuit state.

[0148] [Effects of this embodiment] The control method for the electric vehicle 100 of this embodiment is a method for controlling the electric vehicle 100 by supplying a first torque command value (front torque command value (Tmf ＊ )) to a second motor (rear motor 43R) that drives a second drive wheel (rear wheel 8R) different from the first drive wheel (front wheel 8F), and outputs a second torque command value (rear torque command value (Tmr ＊ )) to the first motor (front motor 43F) and the second motor (rear motor 43R) are driven by receiving power supply from a battery 3, and when the temperature of the battery 3 is lower than a predetermined first threshold temperature, a first torque command value (front torque command value (Tmf ＊ )) and the second torque command value (rear torque command value (Tmr ＊ )) and the combined torque command value (Tmf ＊ +Tmr ＊ ), and outputs a three-phase short circuit command (three-phase short circuit command flag (Fsc=1)) to the second motor (rear motor 43R) to place the second motor (rear motor 43R) in a three-phase short circuit state, and estimates the three-phase short circuit torque (Tsc) generated in the second motor (rear motor 43R) based on the rotation state (rotation speed (ω)) of the second motor (rear motor 43R), and calculates a combined torque command value (Tmf ＊ +Tmr ＊) is corrected based on the three-phase short-circuit torque (Tsc) (the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc).

[0149] By using the above method, the three-phase short-circuit torque (Tsc) generated in the second motor (rear motor 43R) can be offset with high precision by the torque of the first motor (front motor 43F), so that the battery 3 can be warmed up while ensuring torque precision and responsiveness throughout the electric vehicle.

[0150] In this embodiment, when the temperature of the battery 3 becomes lower than the first threshold temperature, the driving states of the first motor (front motor 43F) and the second motor (rear motor 43R) are controlled so that the first motor (front motor 43F) is driven at a first torque command value (front torque command value (Tmf ＊ The second motor (rear motor 43R) is driven based on the second torque command value (rear torque command value (Tmr ＊ )), the first motor (front motor 43F) is driven by the corrected total torque command value (Tmf ＊ +Tmr ＊ When switching to a second state in which the second motor (rear motor 43R) is driven based on a three-phase short circuit command (Fsc=1)) and the second motor (rear motor 43R) is in a three-phase short circuit state, the time constant (τ) for transitioning from the first state to the second state is set based on a predetermined time from when a three-phase short circuit command (three-phase short circuit command flag (Fsc=1)) is output to the second motor (rear motor 43R) until the second motor (rear motor 43R) transitions to the three-phase short circuit state.

[0151] By using the above method, the operating states of the first motor (front motor 43F) and the second motor (rear motor 43R) are changed from the first state to the second state in accordance with the transition time when the second motor (rear motor 43R) changes from a three-phase drive state to a three-phase short circuit state, thereby suppressing torque fluctuations and reducing the sense of discomfort felt by the driver.

[0152] In this embodiment, when the temperature of the battery 3 becomes lower than the first threshold temperature, the driving states of the first motor (front motor 43F) and the second motor (rear motor 43R) are controlled so that the first motor (front motor 43F) is driven at a first torque command value (front torque command value (Tmf ＊ )) and driven by the second motor (rear motor (Tmr ＊ )) is the second torque command value (rear torque command value (Tmr ＊ )), the first motor (front motor 43F) is driven by the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc) and the second motor (rear motor 43R) is switched to the second state in which the second motor is in a three-phase short-circuit state, the corrected total torque command value (Tmf ＊ +Tmr ＊ When the torque command value (Tmf -Tsc) is lower than the maximum torque (Tmax) allowed by the first motor (front motor 43F), the switching from the first state to the second state is permitted (a three-phase short circuit flag (Fsc = 1) is output), and the corrected total torque command value (Tmf ＊ +Tmr ＊ When the torque (Fsc-Tsc) is equal to or greater than the maximum torque (Tmax), switching from the first state to the second state is prohibited (a three-phase short circuit control flag (Fsc=0) is output).

[0153] By using the above method, excessive strain on the first motor (front motor 43F) can be avoided.

[0154] In this embodiment, when the temperature of the battery 3 becomes lower than the first threshold temperature, the driving states of the first motor (front motor 43F) and the second motor (rear motor 43R) are controlled so that the first motor (front motor 43F) is driven at a first torque command value (front torque command value (Tmf ＊ The second motor (rear motor 43R) is driven based on the second torque command value (rear torque command value (Tmr ＊ )), the first motor (front motor 43F) is driven by the corrected total torque command value (Tmf ＊ +Tmr ＊-Tsc) and is switched to a second state in which the second motor (rear motor 43R) is in a three-phase short-circuit state, when the temperature of the inverter (rear inverter 42R) that exchanges power between the second motor (rear motor 43R) and the battery 3 reaches a predetermined second threshold temperature, the driving state is set to the first state, and when the temperature of the inverter (rear inverter 42R) thereafter becomes lower than the second threshold temperature, the driving state is set to the second state.

[0155] The above method can prevent the inverter (rear inverter 42R) from being damaged due to overheating.

[0156] In this embodiment, when the temperature of the battery 3 becomes lower than the first threshold temperature, the driving states of the first motor (front motor 43F) and the second motor (rear motor 43R) are controlled so that the first motor (front motor 43F) is driven at a first torque command value (front torque command value (Tmf ＊ The second motor (rear motor 43R) is driven based on the second torque command value (rear torque command value (Tmr ＊ )), the first motor (front motor 43F) is driven by the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc) and the second motor (rear motor 43R) is switched to a second state in which the driving state is set to a three-phase short circuit state. After the driving state is switched to the second state, a state in which the driving state is set to the second state for a predetermined first predetermined time (T1) and a state in which the driving state is set to the first state for a predetermined second predetermined time (T2) are alternately repeated.

[0157] The above method can prevent damage to the inverter (rear inverter 42R) due to overheating, and can also reduce the processing load.

[0158] In this embodiment, when the driving state is the first state, the first torque command value (front torque command value (Tmf ＊ )) based on the d-axis current command value (idf ＊ (idf1)) and q-axis current command value (iqf ＊(iqf1)) is calculated and output to the first motor (front motor 43F), and a value (idf1+idf2=idf) obtained by adding a predetermined addend (idf2) to the d-axis current command value (idf1) is obtained. ＊ ) toward the first motor (front motor 43F).

[0159] By using the above method, when three-phase short circuit control is not possible even if there is a request to warm up the battery, the first motor (front motor 43F) is heated using d-axis discharge control, thereby improving the heating efficiency of the refrigerant (refrigerant circulation path) that heats the battery 3.

[0160] In this embodiment, when the driving state is the second state, the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc), the d-axis current command value (idf) of the first motor (front motor 43F) in the rotation coordinate system is calculated. ＊ (idf1)) and q-axis current command value (iqf ＊ (iqf1)) is calculated and output to the first motor (front motor 43F), and a value (idf1+idf2=idf) obtained by adding a predetermined addend (idf2) to the d-axis current command value (idf1) is obtained. ＊ ) toward the first motor (front motor 43F).

[0161] By using the above method, d-axis discharge control is performed when three-phase short circuit control is performed, thereby improving the heating efficiency of the refrigerant (refrigerant circulation path) that heats the battery 3, and further reducing the burden on the second motor (rear motor 43R) (and rear inverter 42R) that is in a three-phase short circuit state.

[0162] In this embodiment, the three-phase short-circuit torque (Tsc) is estimated based on the rotation speed (ω) of the second motor (rear motor 43R) and the magnet temperature of the rotor of the second motor (rear motor 43R).

[0163] The above method can expand the operating range in which battery temperature can be controlled by three-phase short-circuit control (for example, the range in which the rotation speed (ω) is 4000 rpm or less), maximizing the effect. Furthermore, it can improve the estimation accuracy of the three-phase short-circuit torque (Tsc).

[0164] The control system for the electric vehicle 100 of this embodiment includes a first motor (front motor 43F) that drives a first drive wheel (8F), a second motor (rear motor 43R) that drives a second drive wheel (8R) different from the first drive wheel (8F), a battery 3 that supplies power to the first motor (front motor 43F) and the second motor (rear motor 43R), and a first torque command value (front torque command value (Tmf ＊ )) to the second motor (rear motor 43R), and outputs a second torque command value (rear torque command value (Tmr ＊ and a control unit (vehicle controller 1) that outputs a first torque command value (front torque command value (Tmf)) to a first motor (front motor 43F) when the temperature of the battery 3 is lower than a predetermined first threshold temperature. ＊ ) and the second torque command value (Tmr ＊ ) and the combined torque command value (Tmf ＊ +Tmr ＊ ), and outputs a three-phase short circuit command (three-phase short circuit command flag (Fsc=1)) to the second motor (rear motor 43R) to place the second motor (rear motor 43R) in a three-phase short circuit state, and estimates the three-phase short circuit torque (Tsc) generated in the second motor (rear motor 43R) based on the rotation state (rotation speed (ω)) of the second motor (rear motor 43R), and calculates a combined torque command value (Tmf ＊ +Tmr ＊ ) is corrected based on the three-phase short-circuit torque (Tsc) (the corrected total torque command value (Tmf ＊ +Tmr ＊ -Tsc).

[0165] With the above configuration, the three-phase short-circuit torque (Tsc) generated in the second motor (rear motor 43R) can be offset with high precision by the torque of the first motor (front motor 43F), so that the battery 3 can be warmed up while ensuring torque precision and responsiveness throughout the electric vehicle.

[0166] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

A control method for an electric vehicle, comprising: outputting a first torque command value to a first motor that drives a first drive wheel; outputting a second torque command value to a second motor that drives a second drive wheel different from the first drive wheel; and wherein the first motor and the second motor are driven by receiving power supply from a battery, When the temperature of the battery is lower than a predetermined first threshold temperature, outputting a combined torque command value obtained by combining the first torque command value and the second torque command value to the first motor; outputting a three-phase short circuit command to the second motor to place the second motor in a three-phase short circuit state; estimating a three-phase short-circuit torque generated in the second motor based on a rotation state of the second motor; a control method for an electric vehicle, the control method comprising correcting the combined torque command value based on the three-phase short-circuit torque; 　 When the temperature of the battery becomes lower than the first threshold temperature, the drive states of the first motor and the second motor are switched from a first state in which the first motor is driven based on the first torque command value and the second motor is driven based on the second torque command value to a second state in which the first motor is driven based on the corrected total torque command value and the second motor is in the three-phase short-circuit state, 2. The control method for an electric vehicle according to claim 1, wherein a time constant for transitioning from the first state to the second state is set based on a predetermined time from when the three-phase short circuit command is output to the second motor until when the second motor transitions to the three-phase short circuit state. 　 When the temperature of the battery becomes lower than the first threshold temperature, the drive states of the first motor and the second motor are switched from a first state in which the first motor is driven based on the first torque command value and the second motor is driven based on the second torque command value to a second state in which the first motor is driven based on the corrected total torque command value and the second motor is in the three-phase short-circuit state, permitting switching from the first state to the second state when the corrected total torque command value is lower than a maximum torque allowable by the first motor; The method for controlling an electric vehicle according to claim 1 , wherein switching from the first state to the second state is prohibited when the corrected total torque command value is equal to or greater than the maximum torque. 　 When the temperature of the battery becomes lower than the first threshold temperature, the drive states of the first motor and the second motor are switched from a first state in which the first motor is driven based on the first torque command value and the second motor is driven based on the second torque command value to a second state in which the first motor is driven based on the corrected total torque command value and the second motor is in the three-phase short-circuit state, 2. The control method for an electric vehicle according to claim 1, wherein the driving state is set to the first state when the temperature of an inverter that exchanges power between the second motor and the battery reaches a predetermined second threshold temperature, and the driving state is set to the second state when the temperature of the inverter thereafter becomes lower than the second threshold temperature. 　 When the temperature of the battery becomes lower than the first threshold temperature, the drive states of the first motor and the second motor are switched between a first state in which the first motor is driven based on the first torque command value and the second motor is driven based on the second torque command value, and a second state in which the first motor is driven based on the corrected total torque command value and the second motor is in the three-phase short-circuit state, 2. The method for controlling an electric vehicle according to claim 1, wherein, after the drive state is switched to the second state, a state in which the drive state is set to the second state for a predetermined first predetermined time and a state in which the drive state is set to the first state for a predetermined second predetermined time are alternately repeated. 　 When the driving state is the first state, a d-axis current command value and a q-axis current command value in a rotating coordinate system of the first motor are calculated based on the first torque command value, and the calculated values ​​are output to the first motor; The method for controlling an electric vehicle according to claim 4 or 5, wherein a value obtained by adding a predetermined additional value to the d-axis current command value is output to the first motor. 　 when the driving state is the second state, calculating a d-axis current command value and a q-axis current command value in a rotating coordinate system of the first motor based on the corrected total torque command value, and outputting the calculated values ​​to the first motor; The method for controlling an electric vehicle according to claim 4 or 5, wherein a value obtained by adding a predetermined additional value to the d-axis current command value is output to the first motor.

2. The method for controlling an electric vehicle according to claim 1, wherein the three-phase short-circuit torque is estimated based on a rotational speed of the second motor and a magnet temperature of a rotor of the second motor. 　 a first motor that drives a first drive wheel; a second motor that drives a second drive wheel different from the first drive wheel; a battery that supplies power to the first motor and the second motor; a control unit that outputs a first torque command value to the first motor and a second torque command value to the second motor, When the temperature of the battery is lower than a predetermined first threshold temperature, The control unit outputting a combined torque command value obtained by combining the first torque command value and the second torque command value to the first motor; outputting a three-phase short circuit command to the second motor to place the second motor in a three-phase short circuit state; estimating a three-phase short-circuit torque generated in the second motor based on a rotation state of the second motor; A control system for an electric vehicle that corrects the combined torque command value based on the three-phase short-circuit torque.

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