A motor torque control method for a dual-motor electric vehicle

Abstract

The application belongs to the technical field of electric vehicles, and particularly relates to a motor torque control method for a double-motor electric vehicle, comprising the following steps: obtaining a motor end demand torque, determining a main drive motor and an auxiliary drive motor, performing main drive motor and auxiliary drive motor torque distribution, and performing torque control on the main drive motor and the auxiliary drive motor; the application considers the actual capacity of the two motors, motor temperature, and motor aging factors caused by load rate, proposes a main / auxiliary drive switching principle, effectively improves vehicle power and prolongs motor service life, effectively avoids motor operation in a low economic zone under the premise of meeting vehicle power, and improves vehicle economy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electric vehicles, and particularly relates to a motor torque control method for a double-motor electric vehicle. BACKGROUND

[0002] At present, most pure electric vehicles adopt single motors, that is, a driving motor, a transmission and a power battery pack. In order to improve the power performance of the whole vehicle, double-motor electric vehicles emerge as the times require. Compared with single-motor driving systems, double-motor driving systems have more flexible torque distribution modes, and the economy and power performance are greatly improved.

[0003] In the current double-motor electric vehicles, during normal driving, the double motors mostly adopt the mode of average torque distribution. However, in the actual driving process, the torque demand of the whole vehicle constantly changes with complex driving conditions. If the average distribution method is used for torque distribution, the demand torque cannot be distributed to the two motors according to the principle of optimal economy, and the energy consumption of the whole vehicle cannot be guaranteed to be the lowest, that is, the economy of the whole vehicle cannot be ensured. In addition, when the capacity of a single motor is limited, the average distribution will cause the "barrel effect", and the full capacity of the other motor cannot be exerted, that is, the optimal power performance of the whole vehicle cannot be achieved. Therefore, the existing double-motor torque average distribution method cannot meet the requirements of users for the economy and power performance of double-motor electric vehicles. SUMMARY

[0004] The application provides a motor torque control method for a double-motor electric vehicle, considers the actual capacity of the two motors, the motor temperature and the motor aging factors caused by the load rate, proposes a main / auxiliary drive switching principle, effectively improves the power performance of the whole vehicle and prolongs the service life of the motor, and under the premise of meeting the power performance of the whole vehicle, effectively avoids the motor working in the low economy zone, and improves the economy of the whole vehicle.

[0005] To achieve the above-mentioned purpose, the application provides a motor torque control method for a double-motor electric vehicle, comprising the following steps:

[0006] S100: obtaining a demand torque at the motor end;

[0007] S200: determining a main drive motor and an auxiliary drive motor;

[0008] S300: performing torque distribution of the main drive motor and the auxiliary drive motor;

[0009] S400: performing torque control on the main drive motor and the auxiliary drive motor.

[0010] The application comprehensively considers the actual capacity of the two motors, the motor temperature and the motor aging factors caused by the load rate of the double-motor power system, performs main / auxiliary drive switching, effectively improves the power performance of the whole vehicle and prolongs the service life of the motor.

[0011] Specifically, the method for obtaining the motor end demand torque in step S100 of the application comprises the following steps:

[0012] Step S110: obtaining the vehicle wheel end demand torque according to the vehicle speed and the accelerator pedal opening degree by searching a MAP;

[0013] Step S120: obtaining the limited vehicle wheel end demand torque by considering the battery allowable discharge power, accessory consumption and other vehicle energy management;

[0014] Step S130: calculating the motor end demand torque according to the limited vehicle wheel end demand torque and in combination with the current gearbox speed ratio and rear axle speed ratio.

[0015] Specifically, the method for determining the main drive motor and the auxiliary drive motor in step S200 of the application, i.e., the main / auxiliary drive switching principle of the application, comprises the following steps: the power system of the application comprises a first motor and a second motor, the first motor is the main drive motor by default after the vehicle is powered on, the second auxiliary motor is the auxiliary motor by default, if any of the following conditions is met, the main drive motor and the auxiliary drive motor are switched, if not met, the first motor remains the main drive motor and the first motor remains the auxiliary motor; the specific conditions are as follows:

[0016] (1) the integral value of the actual torque of the first motor with respect to time minus the integral value of the actual torque of the second motor with respect to time is greater than or equal to A;

[0017] (2) the actual temperature of the first motor minus the actual temperature of the second motor is greater than or equal to t1;

[0018] (3) the actual temperature of the first motor controller minus the actual temperature of the second motor controller is greater than or equal to t2;

[0019] (4) the maximum available torque of the second motor minus the maximum available torque of the first motor is greater than or equal to T1;

[0020] (5) the minimum available torque of the first motor minus the minimum available torque of the second motor is greater than or equal to T2.

[0021] Specifically in step S200 of the application, it is specified that the vehicle power-on to power-off is one driving cycle, the main drive motor and the auxiliary drive motor are set when the vehicle is powered on, and the switching of the main drive motor and the auxiliary drive motor is not performed within the driving cycle.

[0022] Specifically in step S200 of the application, A=638400 N·min, t1=60℃, t2=50℃, T1=500 Nm, and T2=500 Nm.

[0023] Specifically, the torque distribution of the main drive motor and the auxiliary drive motor in step S300 of the application comprises the following steps:

[0024] Step S310: The motor end demand torque is preferentially distributed to the main drive motor, and when the main drive motor distributed torque reaches a set limit, the remaining torque is distributed to the auxiliary drive motor.

[0025] Step S320: The main drive motor is set to 0 torque, main drive motor torque economic lower limit, main drive motor torque economic upper limit and main drive motor maximum torque; and the auxiliary drive motor is set to 0 torque, auxiliary drive motor torque economic lower limit, auxiliary drive motor torque economic upper limit and auxiliary drive motor maximum torque.

[0026] Step S330: Torque loading, first main drive motor loading torque, then auxiliary drive motor loading, in turn alternating loading torque, until the main drive motor is loaded to the main drive motor maximum torque and the auxiliary drive motor is loaded to the auxiliary drive motor maximum torque, torque loading is completed.

[0027] Step S340: Torque unloading, first auxiliary drive motor unloading torque, then main drive motor unloading torque, in turn alternating unloading torque, until the main drive motor and the auxiliary drive motor are unloaded to 0 torque, torque unloading is completed.

[0028] Specifically, the torque loading in step S330 of the present application, i.e. the main / auxiliary drive torque loading strategy, the steps are as follows: S331, main drive motor loading torque is performed until the main drive motor torque is loaded to the main drive motor torque economic upper limit; S332, when the main drive motor torque is loaded to the main drive motor torque economic upper limit, the auxiliary drive motor loading torque is switched; S333, when the auxiliary drive motor torque is loaded to the auxiliary drive motor torque economic upper limit, the main drive motor loading torque is switched; S334, when the main drive motor loading torque reaches the main drive motor maximum torque, the auxiliary drive motor loading torque is switched; S335, in turn alternating loading torque, until the main drive motor is loaded to the main drive motor maximum torque and the auxiliary drive motor is loaded to the auxiliary drive motor maximum torque, torque loading is completed.

[0029] Specifically, the torque unloading in step S340 of the present application, i.e. the main / auxiliary drive torque unloading strategy, the steps are as follows: S341, auxiliary drive motor unloading torque is performed until the auxiliary drive motor torque is unloaded to the auxiliary drive motor torque economic upper limit; S342, when the auxiliary drive motor torque is unloaded to the torque economic upper limit, the main drive motor unloading torque is switched; S343, when the main drive motor torque is unloaded to the main drive motor torque economic upper limit, the auxiliary drive motor unloading torque is switched; S344, when the auxiliary drive motor unloading torque reaches the auxiliary drive motor torque economic lower limit, the main drive motor unloading torque is switched; S345, when the main drive motor unloading torque reaches the main drive motor torque economic lower limit, the auxiliary drive motor unloading torque is switched; S346, when the auxiliary drive motor unloading torque reaches 0 torque, the main drive motor unloading torque is switched; S347, in turn alternating unloading torque, until the main drive motor and the auxiliary drive motor are unloaded to 0 torque, torque unloading is completed.

[0030] Specifically, the application also includes an abnormal situation processing method: if the maximum allowable torque of the motor is limited due to motor failure, the maximum allowable torque of the motor is less than the preset upper limit or lower limit of the motor torque, if the maximum allowable torque of the motor is limited before the motor torque is loaded, step S510 is entered, if the maximum allowable torque of the motor is limited after the motor torque is loaded, step S520 is entered, and if the maximum allowable torque of the limited motor is restored, step S530 is entered.

[0031] Step S510: According to the alternate loading sequence of step S330, the limited motor is loaded to the maximum allowable torque, and then the loading of the limited motor is stopped, and another motor is switched to be loaded until the maximum allowable torque of the limited motor is loaded, and the torque loading is completed.

[0032] Step S520: Adjust the torque of the limited motor to the maximum allowable torque after limitation, and load the down-regulated part of the torque to another motor, and the torque loaded by another motor will not exceed the capacity of the limited motor, i.e. the maximum allowable torque of the limited motor.

[0033] Step S530: The loading sequence is performed according to step S330.

[0034] Specifically, in step S320 of the application, the lower limit of the main drive motor torque economy is 500 Nm, and the upper limit of the main drive motor torque economy is 1000 Nm; the lower limit of the auxiliary drive motor torque economy is 500 Nm, and the upper limit of the auxiliary drive motor torque economy is 1000 Nm.

[0035] Compared with the prior art, the application has the following beneficial effects:

[0036] 1. The actual capacity of the two motors, the motor temperature and the motor aging factors caused by the load rate are comprehensively considered, the main / auxiliary drive switching principle is proposed, the overload or overheating of a single motor is avoided, the vehicle power is effectively improved, and the service life of the motor is prolonged;

[0037] 2. The main / auxiliary drive torque loading and unloading strategy is proposed, the torque output of the dual motor is deployed under the premise of meeting the vehicle power, the motor works in the torque economy lower limit and the torque economy upper limit range, the motor working in the low economy zone is effectively avoided, and the vehicle economy is improved. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a step flow chart of a motor torque control method of a dual motor electric vehicle according to the application.

[0039] Figure 2 is a loading and unloading process schematic diagram of the first case in the specific embodiment of the application.

[0040] Figure 3 is a loading and unloading process schematic diagram of the second case in the specific embodiment of the present application

[0041] Figure 4 is a loading and unloading process schematic diagram of the third case in the specific embodiment of the present application

[0042] Figure 5 is a loading and unloading process schematic diagram of the fourth case in the specific embodiment of the present application DETAILED DESCRIPTION

[0043] The present application will be further described below in conjunction with the accompanying drawings and specific embodiments, and the schematic embodiments of the present application and the description thereof are used to explain the present application and do not constitute an improper limitation on the present application.

[0044] To achieve the above object, the present application provides a motor torque control method for a dual-motor electric vehicle, comprising the following steps:

[0045] S100: obtaining motor end demand torque;

[0046] S200: determining a main drive motor and an auxiliary drive motor;

[0047] S300: performing main drive motor and auxiliary drive motor torque distribution;

[0048] S400: performing torque control on the main drive motor and the auxiliary drive motor.

[0049] The method for obtaining motor end demand torque in step S100 in the embodiment comprises:

[0050] Step S110: obtaining vehicle wheel end demand torque according to vehicle speed and accelerator pedal opening degree by searching a MAP;

[0051] Step S120: obtaining limited vehicle wheel end demand torque by considering battery allowable discharge power, accessory consumption and vehicle energy management;

[0052] Step S130: calculating motor end demand torque according to the limited vehicle wheel end demand torque, in combination with current gearbox speed ratio and rear axle speed ratio.

[0053] The determination method for the main drive motor and the auxiliary drive motor in step S200 in the embodiment, i.e. the main / auxiliary drive switching principle of the present application, comprises the following steps: the power system of the present application comprises a first motor and a second motor, the first motor is the main drive motor by default after the vehicle is powered on, the second auxiliary motor is the auxiliary motor by default, if any of the following conditions is met, the main drive motor and the auxiliary drive motor are switched, if not met, the first motor remains the main drive motor and the first motor remains the auxiliary drive motor; the specific conditions are as follows:

[0054] (1) The integral value of the actual torque of the first motor with respect to time minus the integral value of the actual torque of the second motor with respect to time is greater than or equal to A;

[0055] (2) The actual temperature of the first motor minus the actual temperature of the second motor is greater than or equal to t1;

[0056] (3) The actual temperature of the first motor controller minus the actual temperature of the second motor controller is greater than or equal to t2;

[0057] (4) The maximum available torque of the second motor minus the maximum available torque of the first motor is greater than or equal to T1;

[0058] (5) The minimum available torque of the first motor minus the minimum available torque of the second motor is greater than or equal to T2.

[0059] In step S200 in this embodiment, the power-on to power-off of the whole vehicle is defined as one driving cycle, the main drive motor and the auxiliary drive motor are set when the whole vehicle is powered on, and the switching of the main drive motor and the auxiliary drive motor is not performed within the driving cycle.

[0060] In step S200 in this embodiment, A = 638400 N·min, t1 = 60℃, t2 = 50℃,

[0061] T1 = 500 Nm, and T2 = 500 Nm.

[0062] The torque distribution of the main drive motor and the auxiliary drive motor in step S300 in this embodiment includes the following steps:

[0063] Step S310: The motor end demand torque is preferentially distributed to the main drive motor, and when the main drive motor distributed torque reaches a set limit, the remaining torque is distributed to the auxiliary drive motor.

[0064] Step S320: The main drive motor is set to 0 torque, a main drive motor torque economic lower limit, a main drive motor torque economic upper limit, and a main drive motor maximum torque; and the auxiliary drive motor is set to 0 torque, an auxiliary drive motor torque economic lower limit, an auxiliary drive motor torque economic upper limit, and an auxiliary drive motor maximum torque.

[0065] Step S330: Torque loading, first loading torque of the main drive motor, then loading torque of the auxiliary drive motor, and alternately loading torque in turn, until the main drive motor is loaded to the main drive motor maximum torque and the auxiliary drive motor is loaded to the auxiliary drive motor maximum torque, and the torque loading is ended.

[0066] Step S340: Torque unloading, first unloading torque of the auxiliary drive motor, then unloading torque of the main drive motor, and alternately unloading torque in turn, until the main drive motor and the auxiliary drive motor are both unloaded to 0 torque, and the torque unloading is ended.

[0067] The torque loading in step S330 in the embodiment, i.e., the main / auxiliary drive torque loading strategy, has the following steps: S331, the main drive motor is loaded with torque until the main drive motor torque is loaded to the main drive motor torque economic upper limit; S332, when the main drive motor torque is loaded to the main drive motor torque economic upper limit, the auxiliary drive motor is switched to load torque; S333, when the auxiliary drive motor torque is loaded to the auxiliary drive motor torque economic upper limit, the main drive motor is switched to load torque; S334, when the main drive motor loading torque reaches the main drive motor maximum torque, the auxiliary drive motor is switched to load torque; S335, the torque is loaded alternately in turn until the main drive motor is loaded to the main drive motor maximum torque and the auxiliary drive motor is loaded to the auxiliary drive motor maximum torque, and the torque loading is ended.

[0068] The torque unloading in step S340 in the embodiment, i.e., the main / auxiliary drive torque unloading strategy, has the following steps: S341, the auxiliary drive motor is unloaded with torque until the auxiliary drive motor torque is unloaded to the auxiliary drive motor torque economic upper limit; S342, when the auxiliary drive motor torque is unloaded to the torque economic upper limit, the main drive motor is switched to unload torque; S343, when the main drive motor torque is unloaded to the main drive motor torque economic upper limit, the auxiliary drive motor is switched to unload torque; S344, when the auxiliary drive motor unloading torque is to the auxiliary drive motor torque economic lower limit, the main drive motor is switched to unload torque; S345, when the main drive motor unloading torque is to the main drive motor torque economic lower limit, the auxiliary drive motor is switched to unload torque; S346, when the auxiliary drive motor unloading torque is to 0 torque, the main drive motor is switched to unload torque; S347, the torque is unloaded alternately in turn until the main drive motor and the auxiliary drive motor are both unloaded to 0 torque, and the torque unloading is ended.

[0069] The embodiment further includes an abnormal situation processing method: if the maximum allowable torque of the motor is limited due to motor failure, the maximum allowable torque of the motor is less than the preset motor torque upper limit or the motor torque lower limit, if the maximum allowable torque of the motor is limited before the motor torque is loaded, step S510 is entered, if the maximum allowable torque of the motor is limited after the motor torque is loaded, step S520 is entered, and if the maximum allowable torque of the limited motor is restored, step S530 is entered.

[0070] Step S510: according to the alternate loading sequence of step S330, the limited motor is loaded to the maximum allowable torque, and then the loading of the limited motor is stopped, another motor is switched to load, until the limited motor is loaded to the maximum allowable torque, and the torque loading is ended.

[0071] Step S520: adjust the torque of the limited motor to the maximum allowable torque after limitation, load the down-regulated part of the torque to another motor, and the torque loaded to another motor will not exceed the capacity of the limited motor, i.e., the maximum allowable torque of the limited motor.

[0072] Step S530: Load sequence is performed according to step S330.

[0073] Step S320 in this embodiment: the main drive motor torque economy lower limit is 500 Nm, and the main drive motor torque economy upper limit is 1000 Nm; the auxiliary drive motor torque economy lower limit is 500 Nm, and the auxiliary drive motor torque economy upper limit is 1000 Nm.

[0074] The motor torque loading / unloading strategy is described in detail as follows:

[0075] The main drive motor torque economy lower limit is set to 500 Nm, and the main drive motor torque economy upper limit is set to 1000 Nm; the auxiliary drive motor torque economy lower limit is set to 500 Nm, and the auxiliary drive motor torque economy upper limit is set to 1000 Nm.

[0076] The first case: when 0 Nm≤ required motor total torque≤ main drive motor torque economy upper limit 1000 Nm; if the above condition is met, as shown in Figure 2 The vehicle controller VCU only loads and unloads the main drive motor. Figure 2 The process of loading torque of the main drive motor is shown in sequence from left to right, in which the main drive motor is preferentially loaded torque until the main drive motor torque is loaded to the main drive motor torque economy upper limit 1000 Nm; Figure 2 The sequence from right to left is the sequence of the unloading process.

[0077] The second case: main drive motor torque economy upper limit 1000 Nm < required motor total torque < main drive motor torque economy upper limit 1000 Nm + auxiliary drive motor torque economy lower limit 500 Nm; if the above condition is met, as shown in Figure 3 Torque loading (loading route from left to right): the vehicle controller VCU preferentially loads the main drive motor to the main drive motor torque upper limit 1000 Nm, and loads the remaining required torque to the auxiliary drive motor, and the auxiliary drive motor is loaded to the auxiliary drive motor torque economy lower limit 500 Nm; torque unloading (unloading route from right to left): the vehicle controller VCU preferentially unloads the auxiliary drive motor torque, and then unloads the main drive motor torque.

[0078] The third case: main drive motor torque economy upper limit 1000 Nm + auxiliary drive motor torque lower limit economy 500 Nm≤ required motor total torque≤ main drive motor torque upper limit economy 1000 Nm + auxiliary drive motor torque economy upper limit 1000 Nm, if the above condition is met, as shown in Figure 4As shown, torque loading: the vehicle controller VCU firstly loads the main drive motor to the main drive motor torque economic upper limit 1000Nm, and then loads the remaining demand torque to the auxiliary drive motor, and the auxiliary drive motor is loaded to the auxiliary drive motor torque economic upper limit 1000Nm; torque unloading: the vehicle controller VCU firstly performs auxiliary drive motor torque unloading, and when the auxiliary drive motor torque unloading is to the auxiliary drive motor torque economic lower limit 500Nm, it is switched to the main drive motor torque unloading; when the main drive motor torque unloading is to the main drive motor torque economic lower limit 500Nm, it is switched to the auxiliary drive motor torque unloading; when the auxiliary drive motor torque unloading is to 0Nm, it is switched to the main drive torque unloading again, until the main drive torque is also unloaded to 0Nm.

[0079] The fourth case: main drive motor torque economic upper limit 1000Nm + auxiliary drive motor torque economic upper limit 1000Nm < demand motor total torque ≤ main drive motor maximum allowable torque + auxiliary drive motor maximum allowable torque, such as Figure 4 As shown, torque loading: firstly, the vehicle controller VCU loads the main drive motor to the main drive motor torque economic upper limit 1000Nm, and then loads the auxiliary drive motor to the auxiliary drive motor torque economic upper limit 1000Nm; the vehicle controller VCU loads the main drive motor to the main drive motor maximum allowable torque, and then loads the remaining demand torque to the auxiliary drive motor; torque unloading: the vehicle controller VCU firstly performs auxiliary drive motor torque unloading, and when the auxiliary drive motor torque unloading is to the auxiliary drive motor torque upper limit 1000Nm, it is switched to the main drive motor torque unloading; when the main drive motor torque unloading is to the main drive motor torque economic upper limit 1000Nm, it is switched to the auxiliary drive motor torque unloading; when the auxiliary drive motor torque unloading is to the auxiliary drive motor torque economic lower limit 500Nm, it is switched to the main drive motor torque unloading; when the main drive motor torque unloading is to the main drive motor torque economic lower limit 500Nm, it is switched to the auxiliary drive motor torque unloading; when the auxiliary drive motor torque unloading is to 0Nm, it is switched to the main drive torque unloading again, until the main drive torque is also unloaded to 0Nm.

Claims

1. A method of motor torque control for a dual-motor electric vehicle, characterized by Comprising the following steps: S100: Obtain motor end demand torque; S200: Determine the main drive motor and auxiliary drive motor; S300: Perform main drive motor and auxiliary drive motor torque distribution; S400: Perform torque control on the main drive motor and auxiliary drive motor; The determination method of the main drive motor and the auxiliary drive motor in step S200 comprises the following steps: comprising a first motor and a second motor, the first motor is the main drive motor by default after the vehicle is powered on, and the second motor is the auxiliary drive motor by default; if any of the following conditions is met, the main drive motor and the auxiliary drive motor are switched, and if not, the first motor remains the main drive motor and the second motor remains the auxiliary drive motor; (1) The actual torque of the first motor is integrated with respect to time minus the actual torque of the second motor integrated with respect to time ≥ A; (2) The first motor actual temperature minus the second motor actual temperature ≥ t ; (3) First motor controller actual temperature minus second motor controller actual temperature ≥ t ; (4) The second motor maximum available torque minus the first motor maximum available torque ≥ T ; (5) The first motor minimum available torque minus the second motor minimum available torque ≥ T ; The torque distribution of the main drive motor and the auxiliary drive motor in step S300 comprises the following steps: Step S310: Preferentially distribute the motor end demand torque to the main drive motor, and when the main drive motor distribution torque reaches a set limit, the remaining torque is distributed to the auxiliary drive motor; Step S320: Set 0 torque, main drive motor torque economic lower limit, main drive motor torque economic upper limit and main drive motor maximum torque for the main drive motor; set 0 torque, auxiliary drive motor torque economic lower limit, auxiliary drive motor torque economic upper limit and auxiliary drive motor maximum torque for the auxiliary drive motor; Step S330: Torque loading, first perform main drive motor loading torque, then perform auxiliary drive motor loading, and alternately load torque in turn until the main drive motor is loaded to the main drive motor maximum torque and the auxiliary drive motor is loaded to the auxiliary drive motor maximum torque, and torque loading is completed; Step S340: Torque unloading, first perform auxiliary drive motor unloading torque, then perform main drive motor unloading torque, and alternately unload torque in turn until the main drive motor and the auxiliary drive motor are both unloaded to 0 torque, and torque unloading is completed; The torque loading step in step S330 is as follows: S331, perform main drive motor loading torque until the main drive motor torque is loaded to the main drive motor torque economic upper limit; S332, when the main drive motor torque is loaded to the main drive motor torque economic upper limit, switch to auxiliary drive motor loading torque; S333, when the auxiliary drive motor torque is loaded to the auxiliary drive motor torque economic upper limit, switch to main drive motor loading torque; S334, when the main drive motor loading torque reaches the main drive motor maximum torque, switch to auxiliary drive motor loading torque; S335, alternately load torque in turn until the main drive motor is loaded to the main drive motor maximum torque and the auxiliary drive motor is loaded to the auxiliary drive motor maximum torque, and torque loading is completed; Step S320: The main drive motor torque economic lower limit is 500 Nm, and the main drive motor torque economic upper limit is 1000 Nm; the auxiliary drive motor torque economic lower limit is 500 Nm, and the auxiliary drive motor torque economic upper limit is 1000 Nm.

2. The motor torque control method of a dual-motor electric vehicle according to claim 1, characterized by In step S200, it is specified that the vehicle power-on to power-off is one driving cycle, the main drive motor and the auxiliary drive motor are set when the vehicle is powered on, and the main drive motor and the auxiliary drive motor are not switched within the driving cycle.

3. The motor torque control method for a dual-motor electric vehicle according to claim 1: characterized in that: A = 638400 N • min, t = 60 °C, t = 50 °C, T = 500 Nm, T = 500 Nm.

4. The method of claim 1, wherein The torque unloading step in step S340 is as follows: S341, the auxiliary drive motor unloads torque until the auxiliary drive motor torque is unloaded to the auxiliary drive motor torque economic upper limit; S342, when the auxiliary drive motor torque is unloaded to the torque economic upper limit, the main drive motor unloads torque is switched; S343, when the main drive motor torque is unloaded to the main drive motor torque economic upper limit, the auxiliary drive motor unloads torque is switched; S344, when the auxiliary drive motor unloads torque to the auxiliary drive motor torque economic lower limit, the main drive motor unloads torque is switched; S345, when the main drive motor unloads torque to the main drive motor torque economic lower limit, the auxiliary drive motor unloads torque is switched; S346, when the auxiliary drive motor unloads torque to 0 torque, the main drive motor unloads torque is switched; S347, the torque is unloaded alternately until the main drive motor and the auxiliary drive motor are unloaded to 0 torque, and the torque unloading is ended.

5. The method of claim 1, wherein The abnormal situation processing method also includes: when the maximum allowable torque of the motor is limited, the maximum allowable torque of the motor is less than the preset motor torque upper limit or the motor torque lower limit; if the maximum allowable torque of the motor is limited before the motor torque is loaded, step S510 is entered, if the maximum allowable torque of the motor is limited after the motor torque is loaded, step S520 is entered, and if the maximum allowable torque of the limited motor is restored, step S530 is entered; Step S510: according to the alternate loading sequence of step S330, the limited motor is loaded to the maximum allowable torque, and then the loading of the limited motor is stopped, another motor is loaded, until the maximum allowable torque of the limited motor is loaded, and the torque loading is ended; Step S520: adjust the limited motor torque to the limited maximum allowable torque, load the down-regulated part of the torque to another motor, and the torque loaded by another motor does not exceed the capacity of the limited motor; Step S530: load according to step S330.

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