Optimal electric motor power distribution method for distributed electric drive system

Abstract

Disclosed in the present invention is an optimal electric motor power distribution method for a distributed electric drive system. For electric motors in each dual-electric-motor drive structure or multi-electric-motor drive structure, the output power of the electric motors is separately regulated, with the aim of optimizing the efficiency of the electric motors and ensuring that the operating temperature of all the electric motors is within a nominal value wherever possible. In the present application, optimal power distribution is performed on each group of electric motors in a distributed electric drive system on the basis of a thermal equilibrium strategy, such that the absolute value of a temperature difference between each group of electric motors during operation can be kept within a threshold value wherever possible, and thus the operating efficiency of each group of electric motors is substantially consistent, and too low efficiency of a certain electric motor cannot be caused by overheating, thereby avoiding the necessity to limit the power of the electric motor, and thus finally effectively improving the system safety.

Description

Motor power optimization allocation method for distributed electric drive system

Technical field

[0001] The present invention relates to the technical field of motors and electric controls, and in particular to the technical field of a method for optimizing motor power distribution in a distributed electric drive system. [Background Technology]

[0002] Electric motors are the power source for vehicles such as electric aircraft, new energy vehicles, electric ships, and rail vehicles. While pursuing comfortable and convenient driving performance, efficiency and reliability must also be considered. High efficiency means lower energy consumption and transportation costs, enabling longer driving range with the same energy consumption, while reliability directly impacts transportation safety.

[0003] The existing centralized single-motor drive system is simple in design and easy to implement, but it is unable to actively control the efficiency and temperature of the motor during the driving process. Moreover, the reliability of the entire electric drive system is relatively low, and the operating efficiency and cost cannot be optimized.

[0004] A distributed electric drive system (DPS) includes multiple motors and multiple batteries as power sources to drive each drive shaft as an output terminal, such as the control architecture of a distributed electric drive system disclosed in the invention patent publication number CN115431794A and the distributed electric drive system with multiple voltage platforms disclosed in the invention patent publication number CN114374354B. Referring to Figure 1, a distributed electric drive system is generally based on multiple sets of dual-motor drive structures (coaxial dual-motor drive structures) or multiple sets of multi-motor drive structures (coaxial multi-motor drive structures). For a distributed electric drive system using multiple sets of dual-motor drive structures, each drive shaft is driven by two motors at the same time (for example, drive shaft 1 in Figure 1 is driven by the first and second motors at the same time, while drive shaft 2 is driven by the third and fourth motors at the same time), and each battery powers both motors at the same time (for example, the second and third motors in Figure 1 are powered by battery 1 at the same time, while the fourth and fifth motors (not shown) are powered by battery 2 at the same time). Each motor can be powered by two batteries at the same time. Furthermore, in a distributed electric drive system employing multiple motors, each drive shaft is simultaneously driven by at least three motors, each battery powers at least three motors, and each motor can be powered by at least three batteries. This distributed electric drive system not only optimizes the efficiency and temperature balance of each motor on the same axis based on its operating conditions while maintaining output power, but also offers exceptional overall reliability, making it ideal for vehicles with stringent safety requirements, such as electric vertical lift aircraft.

[0005] Motor overheating is divided into two situations: the motor temperature exceeds the warning temperature (over warning temperature, referred to as Mtr_warning_temp) and the motor temperature exceeds the motor shutdown temperature (over shutdown temperature, referred to as Mtr_sd_temp). Among them, when the motor temperature exceeds the warning temperature, the motor can still be allowed to provide power; when the motor temperature exceeds the motor shutdown temperature, if the motor continues to provide power, it will be damaged, affecting the overall reliability of the system. After exceeding the maximum operating temperature, the motor can usually only continue to operate for a short time (a few minutes) before it is about to be damaged. It is well known that for aircraft such as electric aircraft, safety is one of the most important indicators. When using a distributed electric drive system, it is necessary to solve how to optimize the distribution of motor power to each group of motors, so that before a motor overheats, active adjustments can be made as much as possible to balance the heat generation of this group of motors, so as to avoid limiting or even damaging a motor due to overheating, resulting in a decrease in the performance, reliability and safety of the entire drive system.

[0006] [Summary of the invention]

[0007] The purpose of the present invention is to address the problems in the prior art and propose a method for optimizing motor power distribution in a distributed electric drive system to effectively improve the overall efficiency and safety of the system.

[0008] To achieve the above objectives, the present invention proposes a method for optimizing motor power distribution in a distributed electric drive system. For each motor in a coaxial dual-motor drive structure or a coaxial multi-motor drive structure, the output power of each coaxial motor is adjusted according to the motor temperature in the following manner, provided that the required output power is met:

[0009] If the motor temperature is lower than the warning temperature, the output power of each coaxial motor is adjusted separately until the absolute value of the temperature difference of each motor is within the set threshold;

[0010] If the motor temperature is higher than the warning temperature, the output power of each coaxial motor is adjusted separately to slow down the temperature rise of each motor or reduce the damage to the motor.

[0011] Preferably, when the distributed electric drive system is based on multiple groups of coaxial dual-motor drive structures or coaxial multi-motor drive structures, each group of coaxial dual-motor drive structures or coaxial multi-motor drive structures independently performs motor power optimization allocation; in the coaxial dual-motor drive structure, the first motor and the second motor perform motor power optimization allocation in the following manner:

[0012] If the temperature of the first motor and the temperature of the second motor both exceed the motor shutdown temperature, the output power of the motor closer to the motor shutdown temperature is increased;

[0013] If the temperature of the first motor and the temperature of the second motor both exceed the motor warning temperature and one of them also exceeds the motor shutdown temperature, the output power of the motor whose temperature exceeds the motor shutdown temperature is set to zero, and the other motor is made to provide full power;

[0014] If the first motor temperature and the second motor temperature both exceed the motor warning temperature and do not exceed the motor shutdown temperature, the output power of the motor whose temperature is closer to the motor warning temperature is increased.

[0015] Furthermore, the specific process of optimizing the motor power distribution between the first motor and the second motor is as follows:

[0016] S101 starts the process, reads the first motor temperature and the second motor temperature, and proceeds to step S102;

[0017] S102. Determine whether the first motor temperature is greater than the motor shutdown temperature and the second motor temperature is greater than the motor shutdown temperature. If so, proceed to step S103; otherwise, proceed to step S106;

[0018] S103 determines whether the emergency activation mode is turned on, if so, proceed to step S104, if not, proceed to step S105;

[0019] S104. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (1.1) to (1.5), and end the process; Mtr_over_temp = (Mtr1_temp + Mtr2_temp - 2*Mtr_sd_temp) (1.1); M1_P = (Mtr2_Temp - Mtr_sd_temp) * Axle_pwr / Mtr_over_temp (1.2); M2_P = (Mtr1_Temp - Mtr_sd_temp) * Axle_pwr / Mtr_over_temp (1.3); M1_P_max = 0 (1.4); M2_P_max = 0 (1.5);

[0020] Wherein, Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_over_temp is the overheat temperature of the motor, Axle_pwr is the output power of the transmission shaft, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor. The maximum output power here refers to the maximum output power without damaging the motor, the same below.

[0021] S105. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (2.1) to (2.4), and end the process; M1_P = 0 (2.1); M2_P = 0 (2.2); M1_P_max = 0 (2.3); M2_P_max = 0 (2.4);

[0022] Where M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor;

[0023] S106. Determine whether the first motor temperature is greater than the motor shutdown temperature or the second motor temperature is greater than the motor shutdown temperature. If so, proceed to step S107; otherwise, proceed to step S110.

[0024] S107. Determine whether the first motor temperature is greater than the second motor temperature. If so, proceed to step S108; otherwise, proceed to step S109;

[0025] S108. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (3.1) to (3.4), and end the process; M1_P = 0 (3.1); M2_P = Axle_pwr (3.2); M1_P_max = 0 (3.3); M2_P_max = M2_max_pwr * (Mtr_sd_temp - Mtr2_temp) / (Mtr_sd_temp - Mtr_warning_temp) (3.4);

[0026] Where, Mtr2_temp is the second motor temperature, Mtr_warning_temp is the motor warning temperature, Mtr_sd_temp is the motor shutdown temperature, Axle_pwr is the drive shaft output power, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor;

[0027] S109. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (4.1) to (4.4), and end the process; M2_P = 0 (4.1); M1_P = Axle_pwr (4.2); M2_P_max = 0 (4.3); M1_P_max = M1_max_pwr * (Mtr_sd_temp - Mtr1_temp) / (Mtr_sd_temp - Mtr_warning_temp) (4.4);

[0028] Where, Mtr1_temp is the temperature of the first motor, Mtr_warning_temp is the warning temperature of the motor, Mtr_sd_temp is the shutdown temperature of the motor, Axle_pwr is the output power of the transmission shaft, M1_max_pwr is the maximum output power of the first motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor;

[0029] S110. Determine whether the first motor temperature is lower than the motor shutdown temperature and the second motor temperature is lower than the motor shutdown temperature. If so, proceed to step S111. Otherwise, end the process.

[0030] S111. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (5.1) to (5.5), and end the process; Mtr_udsd_temp=(2*Mtr_sd_temp-Mtr1_temp-Mtr2_temp) (5.1); M1_P=(Mtr_sd_temp-Mtr1_Temp)*Axle_pwr / Mtr_udsd_temp (5.2); M2_P=(Mtr_sd_temp-Mtr2_Temp)*Axle_pwr / Mtr_udsd_temp (5.3); M1_P_max=M1_max_pwr*(Mtr_sd_temp-Mtr1_Temp) / (Mtr_sd_temp-Mtr_warning_temp) (5.4); M2_P_max=M2_max_pwr*(Mtr_sd_temp-Mtr1_Temp) / (Mtr_sd_temp-Mtr_warning_temp) (5.5);

[0031] Where Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_warning_temp is the warning temperature of the motor, Mtr_udsd_temp is the overheat temperature difference of the motor, Axle_pwr is the output power of the transmission shaft, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor.

[0032] Preferably, when the distributed electric drive system is based on multiple groups of coaxial dual-motor drive structures or coaxial multi-motor drive structures, each group of coaxial dual-motor drive structures or coaxial multi-motor drive structures independently performs motor power optimization allocation; in the coaxial dual-motor drive structure, the first motor and the second motor perform motor power optimization allocation in the following manner:

[0033] If only one of the first motor temperature and the second motor temperature exceeds the motor warning temperature, the output power of the motor whose temperature exceeds the motor warning temperature is set to zero, and the other motor is made to provide full power;

[0034] If only one of the first motor temperature and the second motor temperature exceeds the motor shutdown temperature, the output power of the motor whose temperature exceeds the motor shutdown temperature is set to zero, and the other motor is set to provide full power.

[0035] Furthermore, the specific process of optimizing the motor power distribution between the first motor and the second motor is as follows:

[0036] S201 starts the process, reads the first motor temperature and the second motor temperature, and proceeds to step S202;

[0037] S202 determines whether the first motor temperature is greater than the second motor temperature, if so, proceed to step S203, if not, proceed to step S204;

[0038] S203. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (6.1) to (6.4), and end the process; M1_P = 0 (6.1); M2_P = Axle_pwr (6.2); M1_P_max = M1_max_pwr * (Mtr_sd_temp - Mtr1_temp) / (Mtr_sd_temp - Mtr_warning_temp) (6.3); M2_P_max = M2_max_pwr (6.4);

[0039] Where, Mtr1_temp is the temperature of the first motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_warning_temp is the warning temperature of the motor, Axle_pwr is the output power of the transmission shaft, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor;

[0040] S204. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (7.1) to (7.4), and end the process; M2_P = 0 (7.1); M1_P = Axle_pwr (7.2); M2_P_max = M2_max_pwr * (Mtr_sd_temp - Mtr2_temp) / (Mtr_sd_temp - Mtr_warning_temp) (7.3); M1_P_max = M1_max_pwr (7.4);

[0041] Where Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_warning_temp is the warning temperature of the motor, Axle_pwr is the output power of the transmission shaft, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor.

[0042] Preferably, when the distributed electric drive system is based on multiple groups of coaxial dual-motor drive structures or coaxial multi-motor drive structures, each group of coaxial dual-motor drive structures or coaxial multi-motor drive structures independently performs motor power optimization allocation; in the coaxial dual-motor drive structure, the first motor and the second motor perform motor power optimization allocation in the following manner:

[0043] If the temperature of the first motor and the temperature of the second motor do not exceed the motor warning temperature and the absolute value of the temperature difference is greater than the threshold, the output power of the motor with the higher temperature is reduced;

[0044] If the temperature of the first motor and the temperature of the second motor do not exceed the motor warning temperature and the absolute value of the temperature difference is less than the threshold, the output power of the first motor and the second motor is adjusted until the battery is in a state with minimum power consumption.

[0045] Furthermore, the specific process of optimizing the motor power distribution between the first motor and the second motor is as follows:

[0046] S301 starts the process, reads the first motor temperature, the second motor temperature and the motor angular velocity, and proceeds to step S302;

[0047] S302. Calculate the initial power of the first motor, the initial power of the second motor, the initial torque of the first motor, and the initial torque of the second motor according to formulas (8.1) to (8.4), and proceed to step S303; M1_P_init = 0.5*Axle_pwr (8.1); M2_P_init = 0.5*Axle_pwr (8.2); Mtr1_trq_init = M1_P_init / Mtr_omega (8.3); Mtr2_trq_init = M2_P_init / Mtr_omega (8.4);

[0048] Where Mtr1_trq_init is the initial torque of the first motor, Mtr2_trq_init is the initial torque of the second motor, Mtr_omega is the motor angular velocity, Axle_pwr is the output power of the transmission shaft, M1_P_init is the initial power of the first motor, and M2_P_init is the initial power of the second motor.

[0049] S303 determines whether the absolute value of the difference between the first motor temperature and the second motor temperature is greater than a threshold value, if so, proceed to step S304, if not, proceed to step S305;

[0050] S304. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (9.1) to (9.5), and end the process; Temp_Comp_pwr = (Mtr1_Temp - Mtr2_temp) * comp_rate (9.1); M1_P = M1_P_init + Temp_Comp_pwr (9.2); M2_P = M2_P_init - Temp_Comp_pwr (9.3); M1_P_max = M1_max_pwr (9.4); M2_P_max = M2_max_pwr (9.5);

[0051] Where, Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, M2_P_max is the maximum output power of the second motor, Temp_Comp_pwr is the temperature compensated power, comp_rate is the temperature compensated power coefficient, M1_P_init is the initial power of the first motor, and M2_P_init is the initial power of the second motor;

[0052] S305. Calculate the first motor torque, the second motor torque, and the estimated battery power according to formulas (10.1) to (10.3), and proceed to step S306; Mtr1_trq = Mtr1_trq_init (10.1); Mtr2_trq = Mtr2_trq_init (10.2); Battery_Estpwr = (Mtr1_trq / Mtr1_eff+Mtr2_trq / Mtr2_eff)*Mtr_omega (10.3);

[0053] Where Mtr1_trq is the torque of the first motor, Mtr2_trq is the torque of the second motor, Mtr1_trq_init is the initial torque of the first motor, Mtr2_trq_init is the initial torque of the second motor, Mtr1_eff is the efficiency of the first motor, Mtr2_eff is the efficiency of the second motor, Mtr_omega is the angular velocity of the motor, and Battery_Estpwr is the estimated battery power.

[0054] S306. Adjust the first motor torque and the second motor torque until the lowest estimated power of the battery is found, and at the same time make the sum of the first motor torque and the second motor torque equal to the transmission shaft torque, and end the process.

[0055] Furthermore, in step S305 , the first motor efficiency is a function of the first motor torque and the motor speed, and the second motor efficiency is a function of the second motor torque and the motor speed.

[0056] Furthermore, the first motor efficiency and the second motor efficiency are obtained by looking up a motor efficiency table, wherein the motor efficiency table is a three-dimensional table, and the efficiency is a function of torque and speed.

[0057] Furthermore, in step S306 , the search algorithm is a linear search for all combinations of rated step torque changes.

[0058] Beneficial effects of the present invention:

[0059] The present invention discloses a method for optimizing the distribution of motor power in a distributed electric drive system. For each motor in a dual-motor drive structure or a multi-motor drive structure, the output power of each motor is adjusted separately, with the goal of optimizing the efficiency of each motor and ensuring that the operating temperature of each motor is within the nominal value as much as possible. This application optimizes the power distribution of each motor group in a distributed electric drive system based on a thermal balance strategy, so that the absolute value of the temperature difference between each motor group during operation can be kept within a threshold as much as possible, thereby ensuring that the operating efficiency of each motor group is basically consistent. Overheating will not cause the efficiency of a motor to be too low, and thus its power will not have to be limited. Ultimately, the system safety will be effectively improved.

[0060] The features and advantages of the present invention will be described in detail through embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0061] Figure 1 is a schematic structural diagram of a dual-motor drive system;

[0062] FIG2 is a specific flow chart of optimizing motor power distribution between the first motor and the second motor in case 1 of the embodiment;

[0063] FIG3 is a specific flow chart of optimizing motor power distribution between the first motor and the second motor in case 2 of the embodiment;

[0064] FIG4 is a specific flow chart of optimizing motor power distribution between the first motor and the second motor in case 3 of the embodiment;

[0065] FIG5 is a data comparison diagram of the first scenario of the embodiment;

[0066] FIG6 is a data comparison diagram of the second situation of the embodiment in case 1;

[0067] FIG7 is a data comparison diagram of the third situation of the embodiment in case 1;

[0068] FIG8 is a data comparison diagram of the fourth situation of the embodiment in case 1;

[0069] FIG9 is a data comparison diagram of the embodiment under the transformation of case 1 and case 2;

[0070] FIG10 is a data comparison diagram of the embodiment under situation three;

[0071] FIG11 is a data comparison diagram of the embodiment under the transformation of case 2 and case 3. [Specific implementation method]

[0072] Referring to Figures 1 to 4 , taking a distributed electric drive system based on a multi-group dual-motor drive structure as an example, the motor power optimization distribution method of the distributed electric drive system of the present invention adjusts the output power of each coaxial motor in the coaxial dual-motor drive structure according to the following method based on the motor temperature, while meeting the required output power:

[0073] If the motor temperature is lower than the warning temperature, the output power of each coaxial motor is adjusted separately until the absolute value of the temperature difference of each motor is within the set threshold;

[0074] If the motor temperature is higher than the warning temperature, the output power of each coaxial motor is adjusted separately to slow down the temperature rise of each motor or reduce the damage to the motor.

[0075] Each coaxial dual-motor drive structure independently optimizes motor power allocation. The optimized power allocation for the first and second motors covers three scenarios: Case 1 (both motors overheat), Case 2 (one motor overheats), and Case 3 (both motors are within the normal temperature range). Motor overheating in these scenarios refers to exceeding the warning temperature. For example, for a motor with 180°C insulation, the motor warning temperature is 120°C, the motor shutdown temperature is 160°C, and the temperature difference threshold is 10°C.

[0076] In case one, if the temperature of the first motor and the temperature of the second motor both exceed the motor shutdown temperature, the output power of the motor closer to the motor shutdown temperature is increased. In an emergency, both the first motor and the second motor need to continue to output power to extend the flight time of the aircraft. This strategy can extend the life of the first motor and the second motor as much as possible, thereby improving the safety of the system. Figures 5 and 6 are schematic diagrams of this situation when the emergency signal is not triggered and when it is triggered, respectively. Among them, the horizontal axis is normalized time (unit is s), and the horizontal axes of Figures 7-11 are the same as those of Figures 5-6.

[0077] In scenario 1, if the temperatures of both the first and second motors exceed the motor warning temperature, and one of them also exceeds the motor shutdown temperature, the output power of the motor exceeding the motor shutdown temperature is reduced to zero, and the other motor provides full power. This strategy minimizes damage to both motors, thereby improving system safety. Refer to Figure 7, where the section corresponding to "Both motors overheat, with the first motor exceeding the shutdown temperature" pertains to this scenario.

[0078] In scenario 1, if the temperatures of both the first and second motors exceed the motor warning temperature but remain below the motor shutdown temperature, the motor with a temperature closer to the motor warning temperature is given a higher output power. This strategy ensures that both motor temperatures remain within the motor shutdown temperature as much as possible, thereby improving system safety. (See Figures 7 and 9 for the section corresponding to "Both motors overheat but below the shutdown temperature" for this scenario. Figure 8 also provides a schematic diagram of this scenario.)

[0079] 2 , the specific process of optimizing the motor power distribution between the first motor and the second motor is as follows:

[0080] S101 starts the process, reads the first motor temperature and the second motor temperature, and proceeds to step S102;

[0081] S102. Determine whether the first motor temperature is greater than the motor shutdown temperature and the second motor temperature is greater than the motor shutdown temperature. If so, proceed to step S103; otherwise, proceed to step S106;

[0082] S103 determines whether the emergency activation mode is turned on, if so, proceed to step S104, if not, proceed to step S105;

[0083] S104. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (1.1) to (1.5), and end the process; Mtr_over_temp = (Mtr1_temp + Mtr2_temp - 2*Mtr_sd_temp) (1.1); M1_P = (Mtr2_Temp - Mtr_sd_temp) * Axle_pwr / Mtr_over_temp (1.2); M2_P = (Mtr1_Temp - Mtr_sd_temp) * Axle_pwr / Mtr_over_temp (1.3); M1_P_max = 0 (1.4); M2_P_max = 0 (1.5);

[0084] Where Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_over_temp is the overheat temperature of the motor, Axle_pwr is the output power of the transmission shaft, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor.

[0085] S105. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (2.1) to (2.4), and end the process; M1_P = 0 (2.1); M2_P = 0 (2.2); M1_P_max = 0 (2.3); M2_P_max = 0 (2.4);

[0086] Where M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor;

[0087] S106. Determine whether the first motor temperature is greater than the motor shutdown temperature or the second motor temperature is greater than the motor shutdown temperature. If so, proceed to step S107; otherwise, proceed to step S110.

[0088] S107. Determine whether the first motor temperature is greater than the second motor temperature. If so, proceed to step S108; otherwise, proceed to step S109;

[0089] S108. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (3.1) to (3.4), and end the process; M1_P = 0 (3.1); M2_P = Axle_pwr (3.2); M1_P_max = 0 (3.3); M2_P_max = M2_max_pwr * (Mtr_sd_temp - Mtr2_temp) / (Mtr_sd_temp - Mtr_warning_temp) (3.4);

[0090] Where, Mtr2_temp is the second motor temperature, Mtr_warning_temp is the motor warning temperature, Mtr_sd_temp is the motor shutdown temperature, Axle_pwr is the drive shaft output power, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor;

[0091] S109. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (4.1) to (4.4), and end the process; M2_P = 0 (4.1); M1_P = Axle_pwr (4.2); M2_P_max = 0 (4.3); M1_P_max = M1_max_pwr * (Mtr_sd_temp - Mtr1_temp) / (Mtr_sd_temp - Mtr_warning_temp) (4.4);

[0092] Where, Mtr1_temp is the temperature of the first motor, Mtr_warning_temp is the warning temperature of the motor, Mtr_sd_temp is the shutdown temperature of the motor, Axle_pwr is the output power of the transmission shaft, M1_max_pwr is the maximum output power of the first motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor;

[0093] S110. Determine whether the first motor temperature is lower than the motor shutdown temperature and the second motor temperature is lower than the motor shutdown temperature. If so, proceed to step S111. Otherwise, end the process.

[0094] S111. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (5.1) to (5.5), and end the process; Mtr_udsd_temp=(2*Mtr_sd_temp-Mtr1_temp-Mtr2_temp) (5.1); M1_P=(Mtr_sd_temp-Mtr1_Temp)*Axle_pwr / Mtr_udsd_temp (5.2); M2_P=(Mtr_sd_temp-Mtr2_Temp)*Axle_pwr / Mtr_udsd_temp (5.3); M1_P_max=M1_max_pwr*(Mtr_sd_temp-Mtr1_Temp) / (Mtr_sd_temp-Mtr_warning_temp) (5.4); M2_P_max=M2_max_pwr*(Mtr_sd_temp-Mtr2_Temp) / (Mtr_sd_temp-Mtr_warning_temp) (5.5);

[0095] Where Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_warning_temp is the warning temperature of the motor, Mtr_udsd_temp is the overheat temperature difference of the motor, Axle_pwr is the output power of the transmission shaft, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor.

[0096] In the second scenario, if only one of the first and second motor temperatures exceeds the motor warning temperature, the output power of the motor exceeding the motor warning temperature is set to zero, and the other motor provides full power. This strategy allows the overheated motor to cool as quickly as possible, ultimately ensuring that both motors do not exceed the motor warning temperature, thereby improving system safety. Refer to Figure 9 , where the sections corresponding to "One motor (the second motor) is overheated and below the shutdown temperature" and "One motor (the first motor) is overheated and below the shutdown temperature" fall under this scenario. Furthermore, refer to Figure 11 , where the section corresponding to "One motor (the first motor) is overheated and below the shutdown temperature" also falls under this scenario.

[0097] In the second scenario, if only one of the first and second motor temperatures exceeds the motor shutdown temperature, the output power of the motor exceeding the shutdown temperature is reduced to zero, and the other motor provides full power. This strategy allows the overheated motor to cool as quickly as possible, ultimately ensuring that both motors do not exceed the motor warning temperature, thereby improving system safety. Refer to Figure 9, where the sections corresponding to "One motor (the second motor) is overheated and exceeds the shutdown temperature" and "One motor (the first motor) is overheated and exceeds the shutdown temperature" refer to this scenario.

[0098] 3 , the specific process of optimizing the motor power distribution between the first motor and the second motor is as follows:

[0099] S201 starts the process, reads the first motor temperature and the second motor temperature, and proceeds to step S202;

[0100] S202 determines whether the first motor temperature is greater than the second motor temperature, if so, proceed to step S203, if not, proceed to step S204;

[0101] S203. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (6.1) to (6.4), and end the process; M1_P = 0 (6.1); M2_P = Axle_pwr (6.2); M1_P_max = M1_max_pwr * (Mtr_sd_temp - Mtr1_temp) / (Mtr_sd_temp - Mtr_warning_temp) (6.3); M2_P_max = M2_max_pwr (6.4);

[0102] Where, Mtr1_temp is the temperature of the first motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_warning_temp is the warning temperature of the motor, Axle_pwr is the output power of the transmission shaft, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor;

[0103] S204. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (7.1) to (7.4), and end the process; M2_P = 0 (7.1); M1_P = Axle_pwr (7.2); M2_P_max = M2_max_pwr * (Mtr_sd_temp - Mtr2_temp) / (Mtr_sd_temp - Mtr_warning_temp) (7.3); M1_P_max = M1_max_pwr (7.4);

[0104] Where Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_warning_temp is the warning temperature of the motor, Axle_pwr is the output power of the transmission shaft, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor.

[0105] In case three, if the temperature of the first motor and the temperature of the second motor do not exceed the motor warning temperature and the absolute value of the temperature difference is greater than the threshold, the output power of the motor with the higher temperature is reduced. This method can make the absolute value of the temperature difference between the two motors less than the threshold, and at the same time as low as possible below the motor warning temperature, ultimately improving system safety; if the temperature of the first motor and the temperature of the second motor do not exceed the motor warning temperature and the absolute value of the temperature difference is less than the threshold, the output power of the first motor and the second motor is adjusted until the battery is in a state of minimum power consumption. Under this strategy, the purpose of motor power allocation is to minimize the total loss of the two motors (minimize the total input power at the same output power), ultimately minimizing battery power consumption and effectively increasing the mileage of the aircraft. Refer to Figure 11, where the part corresponding to "both motors are not overheating" is a schematic diagram of the switching between the above two situations. In addition, Figure 10 is also a schematic diagram of the switching between the above two situations.

[0106] 4 , the specific process of optimizing the motor power distribution between the first motor and the second motor is as follows:

[0107] S301 starts the process, reads the first motor temperature, the second motor temperature and the motor angular velocity, and proceeds to step S302;

[0108] S302. Calculate the initial power of the first motor, the initial power of the second motor, the initial torque of the first motor, and the initial torque of the second motor according to formulas (8.1) to (8.4), and proceed to step S303; M1_P_init = 0.5*Axle_pwr (8.1); M2_P_init = 0.5*Axle_pwr (8.2); Mtr1_trq_init = M1_P_init / Mtr_omega (8.3); Mtr2_trq_init = M2_P_init / Mtr_omega (8.4);

[0109] Where Mtr1_trq_init is the initial torque of the first motor, Mtr2_trq_init is the initial torque of the second motor, Mtr_omega is the motor angular velocity, Axle_pwr is the output power of the transmission shaft, M1_P_init is the initial power of the first motor, and M2_P_init is the initial power of the second motor.

[0110] S303 determines whether the absolute value of the difference between the first motor temperature and the second motor temperature is greater than a threshold value, if so, proceed to step S304, if not, proceed to step S305;

[0111] S304. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (9.1) to (9.5), and end the process; Temp_Comp_pwr = (Mtr1_Temp - Mtr2_temp) * comp_rate (9.1); M1_P = M1_P_init + Temp_Comp_pwr (9.2); M2_P = M2_P_init - Temp_Comp_pwr (9.3); M1_P_max = M1_max_pwr (9.4); M2_P_max = M2_max_pwr (9.5);

[0112] Where, Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, M2_P_max is the maximum output power of the second motor, Temp_Comp_pwr is the temperature compensated power, comp_rate is the temperature compensated power coefficient, M1_P_init is the initial power of the first motor, and M2_P_init is the initial power of the second motor;

[0113] S305. Calculate the first motor torque, the second motor torque, and the estimated battery power according to formulas (10.1) to (10.3), and proceed to step S306; Mtr1_trq = Mtr1_trq_init (10.1); Mtr2_trq = Mtr2_trq_init (10.2); Battery_Estpwr = (Mtr1_trq / Mtr1_eff+Mtr2_trq / Mtr2_eff)*Mtr_omega (10.3);

[0114] Where Mtr1_trq is the torque of the first motor, Mtr2_trq is the torque of the second motor, Mtr1_trq_init is the initial torque of the first motor, Mtr2_trq_init is the initial torque of the second motor, Mtr1_eff is the efficiency of the first motor, Mtr2_eff is the efficiency of the second motor, Mtr_omega is the angular velocity of the motor, and Battery_Estpwr is the estimated battery power.

[0115] S306. Adjust the first motor torque and the second motor torque until the lowest estimated power of the battery is found, and at the same time make the sum of the first motor torque and the second motor torque equal to the transmission shaft torque, and end the process.

[0116] In step S305 , the first motor efficiency is a function of the first motor torque and the motor speed, and the second motor efficiency is a function of the second motor torque and the motor speed.

[0117] The first motor efficiency and the second motor efficiency are obtained by looking up the motor efficiency table. The motor efficiency table is shown in Table 1 below:

[0118] Table 1 Motor efficiency table

[0119] In step S306 , the search algorithm is a linear search for all combinations of rated step torque changes.

[0120] The present application optimizes the power distribution of each motor in each group based on thermal balance in a distributed electric drive system, so that the absolute value of the temperature difference of each motor in each group during operation under different loads can be kept within the threshold as soon as possible, thereby making the output power of each motor in each group basically consistent, and the power of a certain motor will not be limited or the motor will be damaged due to overheating, thereby effectively improving the safety of the system.

[0121] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention falls within the protection scope of the present invention.

Claims

1. A method for optimizing motor power distribution in a distributed electric drive system, characterized by: For each motor in a coaxial dual-motor drive structure or a coaxial multi-motor drive structure, under the premise of meeting the required output power, the output power of each coaxial motor is adjusted according to the motor temperature in the following manner: If the motor temperature is lower than the warning temperature, the output power of each coaxial motor is adjusted separately until the absolute value of the temperature difference of each motor is within the set threshold; If the motor temperature is higher than the warning temperature, the output power of each coaxial motor is adjusted separately to slow down the temperature rise of each motor or reduce the damage to the motor.

2. The method for optimizing motor power distribution of a distributed electric drive system according to claim 1, wherein: When the distributed electric drive system is based on multiple groups of coaxial dual-motor drive structures or coaxial multi-motor drive structures, each group of coaxial dual-motor drive structures or coaxial multi-motor drive structures independently optimizes motor power distribution. In the coaxial dual-motor drive structure, the method for optimizing motor power distribution between the first motor and the second motor is as follows: If the temperature of the first motor and the temperature of the second motor both exceed the motor shutdown temperature, the output power of the motor closer to the motor shutdown temperature is increased; If the temperature of the first motor and the temperature of the second motor both exceed the motor warning temperature and one of them also exceeds the motor shutdown temperature, the output power of the motor whose temperature exceeds the motor shutdown temperature is set to zero, and the other motor is made to provide full power; If the first motor temperature and the second motor temperature both exceed the motor warning temperature and do not exceed the motor shutdown temperature, the output power of the motor whose temperature is closer to the motor warning temperature is increased.

3. The motor power optimization distribution method of the distributed electric drive system according to claim 2, characterized in that: The specific process of optimizing the motor power distribution between the first motor and the second motor is as follows: S101 starts the process, reads the first motor temperature and the second motor temperature, and proceeds to step S102; S102. Determine whether the first motor temperature is greater than the motor shutdown temperature and the second motor temperature is greater than the motor shutdown temperature. If so, proceed to step S103; otherwise, proceed to step S106; S103 determines whether the emergency activation mode is turned on, if so, proceed to step S104, if not, proceed to step S105; S104. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (1.1) to (1.5), and end the process; Mtr_over_temp=(Mtr1_temp+Mtr2_temp-2*Mtr_sd_temp) (1.1); M1_P=(Mtr2_Temp-Mtr_sd_temp)*Axle_pwr / Mtr_over_temp (1.2); M2_P=(Mtr1_Temp-Mtr_sd_temp)*Axle_pwr / Mtr_over_temp (1.3); M1_P_max=0 (1.4); M2_P_max=0 (1.5); Where Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_over_temp is the overheat temperature of the motor, Axle_pwr is the output power of the transmission shaft, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor. S105. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (2.1) to (2.4), and end the process; M1_P=0 (2.1); M2_P=0 (2.2); M1_P_max=0 (2.3); M2_P_max=0 (2.4); Where M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor; S106. Determine whether the first motor temperature is greater than the motor shutdown temperature or the second motor temperature is greater than the motor shutdown temperature. If so, proceed to step S107; otherwise, proceed to step S110. S107. Determine whether the first motor temperature is greater than the second motor temperature. If so, proceed to step S108; otherwise, proceed to step S109; S108. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (3.1) to (3.4), and end the process; M1_P=0 (3.1); M2_P = Axle_pwr (3.2); M1_P_max=0 (3.3); M2_P_max=M2_max_pwr*(Mtr_sd_temp-Mtr2_temp) / (Mtr_sd_temp- Mtr_warning_temp) (3.4); Where, Mtr2_temp is the second motor temperature, Mtr_warning_temp is the motor warning temperature, Mtr_sd_temp is the motor shutdown temperature, Axle_pwr is the drive shaft output power, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor; S109. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (4.1) to (4.4), and end the process; M2_P=0 (4.1); M1_P = Axle_pwr (4.2); M2_P_max=0 (4.3); M1_P_max=M1_max_pwr*(Mtr_sd_temp-Mtr1_temp) / (Mtr_sd_temp- Mtr_warning_temp) (4.4); Where, Mtr1_temp is the temperature of the first motor, Mtr_warning_temp is the warning temperature of the motor, Mtr_sd_temp is the shutdown temperature of the motor, Axle_pwr is the output power of the transmission shaft, M1_max_pwr is the maximum output power of the first motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor; S110. Determine whether the first motor temperature is lower than the motor shutdown temperature and the second motor temperature is lower than the motor shutdown temperature. If so, proceed to step S111. Otherwise, end the process. S111. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (5.1) to (5.5), and end the process; Mtr_udsd_temp=(2*Mtr_sd_temp-Mtr1_temp-Mtr2_temp) (5.1); M1_P=(Mtr_sd_temp-Mtr1_Temp)*Axle_pwr / Mtr_udsd_temp (5.2); M2_P=(Mtr_sd_temp-Mtr2_Temp)*Axle_pwr / Mtr_udsd_temp (5.3); M1_P_max=M1_max_pwr*(Mtr_sd_temp-Mtr1_Temp) / (Mtr_sd_temp-Mtr_warning_temp) (5.4); M2_P_max=M2_max_pwr*(Mtr_sd_temp-Mtr2_Temp) / (Mtr_sd_temp-Mtr_warning_temp) (5.5); Where Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_warning_temp is the warning temperature of the motor, Mtr_udsd_temp is the overheat temperature difference of the motor, Axle_pwr is the output power of the transmission shaft, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor.

4. The method for optimizing motor power distribution of a distributed electric drive system according to claim 1, wherein: When the distributed electric drive system is based on multiple groups of coaxial dual-motor drive structures or coaxial multi-motor drive structures, each group of coaxial dual-motor drive structures or coaxial multi-motor drive structures independently optimizes motor power distribution. In the coaxial dual-motor drive structure, the method for optimizing motor power distribution between the first motor and the second motor is as follows: If only one of the first motor temperature and the second motor temperature exceeds the motor warning temperature, the output power of the motor whose temperature exceeds the motor warning temperature is set to zero, and the other motor is made to provide full power; If only one of the first motor temperature and the second motor temperature exceeds the motor shutdown temperature, the output power of the motor whose temperature exceeds the motor shutdown temperature is set to zero, and the other motor is set to provide full power.

5. The motor power optimization distribution method of the distributed electric drive system according to claim 4, characterized in that: The specific process of optimizing the motor power distribution between the first motor and the second motor is as follows: S201 starts the process, reads the first motor temperature and the second motor temperature, and proceeds to step S202; S202 determines whether the first motor temperature is greater than the second motor temperature, if so, proceed to step S203, if not, proceed to step S204; S203. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (6.1) to (6.4), and end the process; M1_P=0 (6.1); M2_P = Axle_pwr (6.2); M1_P_max=M1_max_pwr*(Mtr_sd_temp-Mtr1_temp) / (Mtr_sd_temp-Mtr_warning_temp) (6.3); M2_P_max=M2_max_pwr (6.4); Where, Mtr1_temp is the first motor temperature, Mtr_sd_temp is the motor shutdown temperature, Mtr_warning_temp is the motor warning temperature, Axle_pwr is the transmission shaft output power, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, and M1_P is the maximum output power of the first motor. The output power of the first motor, M2_P, is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor; S204. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (7.1) to (7.4), and end the process; M2_P=0 (7.1); M1_P = Axle_pwr (7.2); M2_P_max=M2_max_pwr*(Mtr_sd_temp-Mtr2_temp) / (Mtr_sd_temp-Mtr_warning_temp) (7.3); M1_P_max=M1_max_pwr (7.4); Where Mtr2_temp is the temperature of the second motor, Mtr_sd_temp is the shutdown temperature of the motor, Mtr_warning_temp is the warning temperature of the motor, Axle_pwr is the output power of the transmission shaft, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, and M2_P_max is the maximum output power of the second motor.

6. The motor power optimization distribution method of a distributed electric drive system according to claim 1, characterized in that: When the distributed electric drive system is based on multiple groups of coaxial dual-motor drive structures or coaxial multi-motor drive structures, each group of coaxial dual-motor drive structures or coaxial multi-motor drive structures independently optimizes motor power distribution. In the coaxial dual-motor drive structure, the method for optimizing motor power distribution between the first motor and the second motor is as follows: If the temperature of the first motor and the temperature of the second motor do not exceed the motor warning temperature and the absolute value of the temperature difference is greater than the threshold, the output power of the motor with the higher temperature is reduced; If the temperature of the first motor and the temperature of the second motor do not exceed the motor warning temperature and the absolute value of the temperature difference is less than the threshold, the output power of the first motor and the second motor is adjusted until the battery is in a state with minimum power consumption.

7. The motor power optimization distribution method of the distributed electric drive system according to claim 6, characterized in that: The specific process of optimizing the motor power distribution between the first motor and the second motor is as follows: S301 starts the process, reads the first motor temperature, the second motor temperature and the motor angular velocity, and proceeds to step S302; S302. Calculate the initial power of the first motor, the initial power of the second motor, the initial torque of the first motor, and the initial torque of the second motor according to formulas (8.1) to (8.4), and proceed to step S303; M1_P_init=0.5*Axle_pwr (8.1); M2_P_init=0.5*Axle_pwr (8.2); Mtr1_trq_init=M1_P_init / Mtr_omega (8.3); Mtr2_trq_init=M2_P_init / Mtr_omega (8.4); Where Mtr1_trq_init is the initial torque of the first motor, Mtr2_trq_init is the initial torque of the second motor, Mtr_omega is the motor angular velocity, Axle_pwr is the output power of the transmission shaft, M1_P_init is the initial power of the first motor, and M2_P_init is the initial power of the second motor. S303 determines whether the absolute value of the difference between the first motor temperature and the second motor temperature is greater than a threshold value, if so, proceed to step S304, if not, proceed to step S305; S304. Calculate the output power of the first motor, the output power of the second motor, the maximum output power of the first motor, and the maximum output power of the second motor according to formulas (9.1) to (9.5), and end the process; Temp_Comp_pwr=(Mtr1_Temp-Mtr2_temp)*comp_rate (9.1); M1_P=M1_P_init+Temp_Comp_pwr (9.2); M2_P=M2_P_init-Temp_Comp_pwr (9.3); M1_P_max=M1_max_pwr (9.4); M2_P_max=M2_max_pwr (9.5); Where, Mtr1_temp is the temperature of the first motor, Mtr2_temp is the temperature of the second motor, M1_max_pwr is the maximum output power of the first motor, M2_max_pwr is the maximum output power of the second motor, M1_P is the output power of the first motor, M2_P is the output power of the second motor, M1_P_max is the maximum output power of the first motor, M2_P_max is the maximum output power of the second motor, Temp_Comp_pwr is the temperature compensated power, comp_rate is the temperature compensated power coefficient, M1_P_init is the initial power of the first motor, and M2_P_init is the initial power of the second motor; S305. Calculate the first motor torque, the second motor torque, and the estimated battery power according to formulas (10.1) to (10.3), and proceed to step S306. Mtr1_trq=Mtr1_trq_init (10.1); Mtr2_trq=Mtr2_trq_init (10.2); Battery_Estpwr=(Mtr1_trq / Mtr1_eff+Mtr2_trq / Mtr2_eff)*Mtr_omega(10.3); Where Mtr1_trq is the torque of the first motor, Mtr2_trq is the torque of the second motor, Mtr1_trq_init is the initial torque of the first motor, Mtr2_trq_init is the initial torque of the second motor, Mtr1_eff is the efficiency of the first motor, Mtr2_eff is the efficiency of the second motor, Mtr_omega is the angular velocity of the motor, and Battery_Estpwr is the estimated battery power. S306. Adjust the first motor torque and the second motor torque until the lowest estimated power of the battery is found, and at the same time make the sum of the first motor torque and the second motor torque equal to the transmission shaft torque, and end the process.

8. The method for optimizing motor power distribution of a distributed electric drive system according to claim 7, wherein: In step S305 , the first motor efficiency is a function of the first motor torque and the motor speed, and the second motor efficiency is a function of the second motor torque and the motor speed.

9. The method for optimizing motor power distribution of a distributed electric drive system according to claim 8, characterized in that: The first motor efficiency and the second motor efficiency are respectively obtained by looking up a motor efficiency table.

10. The motor power optimization distribution method of a distributed electric drive system according to claim 7, characterized in that: In step S306 , the search algorithm is a linear search for all combinations of rated step torque changes.

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