Torque Distribution Method for Four-Wheel In-Wheel Motor Driven Vehicle Considering Motor Efficiency Differences

Abstract

The present invention discloses a torque distribution method for a four-wheel in-wheel motor-driven vehicle considering the motor efficiency difference, which relates to the technical field of new energy vehicles and includes the following steps: obtaining the maximum driving force of the vehicle according to the vehicle speed of the four-wheel in-wheel motor-driven vehicle; obtaining the total required torque of the vehicle according to the maximum driving force of the vehicle and the pedal opening; establishing a driving efficiency objective function and constraint conditions based on the total required torque of the vehicle; performing torque distribution optimization to solve according to the driving efficiency objective function and constraint conditions to obtain the optimal distribution coefficient; correcting the optimal distribution coefficient according to the torque slope limit to obtain the torque distribution result of the four-wheel in-wheel motor-driven vehicle, thereby completing the torque distribution of the four-wheel in-wheel motor-driven vehicle considering the motor efficiency difference. The present invention solves the problem that the traditional torque distribution method causes the motor to operate in a low-efficiency region due to ignoring the efficiency map between motors.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and particularly to a torque distribution method for a four-wheel in-wheel motor drive vehicle considering the efficiency difference of motors. Background Art

[0002] With the increasing prominence of environmental and energy problems, new energy vehicles, as one of the important alternatives to traditional fuel vehicles, have received extensive attention in the automotive industry. A four-wheel in-wheel motor drive vehicle is a vehicle that uses independent control of the motors on each wheel to achieve driving and braking. Compared with traditional central drive and traditional four-wheel drive, this structure can provide better maneuverability, stability and energy efficiency. In a four-wheel in-wheel motor drive vehicle, torque distribution refers to distributing the torque generated by the motors to each wheel to achieve vehicle acceleration, braking and steering. Traditional torque distribution methods mainly calculate the forces required by the vehicle based on the vehicle's dynamic model to determine the torque distribution ratio on each wheel. However, traditional torque distribution methods ignore the differences in the efficiency maps between motors. In fact, due to inconsistent manufacturing, working conditions and service life, there are significant differences in the efficiency distributions among the four in-wheel motors. The traditional torque distribution method for the four in-wheel motors is prone to causing the motors to operate in low-efficiency regions due to ignoring this efficiency difference, reducing the driving range of the vehicle. Summary of the Invention

[0003] Aiming at the above deficiencies in the prior art, the torque distribution method for a four-wheel in-wheel motor drive vehicle considering the efficiency difference of motors provided by the present invention solves the problem that the traditional torque distribution method causes the motors to operate in low-efficiency regions due to ignoring the efficiency maps between motors.

[0004] To achieve the above invention objective, the technical solution adopted by the present invention is: a torque distribution method for a four-wheel in-wheel motor drive vehicle considering the efficiency difference of motors, including the following steps:

[0005] S1: Obtain the maximum driving force of the vehicle according to the vehicle speed of the four-wheel in-wheel motor drive vehicle;

[0006] S2: Obtain the total required torque of the vehicle according to the maximum driving force of the vehicle and the pedal opening;

[0007] S3: Based on the total required torque of the vehicle, establish a driving efficiency objective function and constraint conditions;

[0008] S4: According to the driving efficiency objective function and constraint conditions, perform torque distribution optimization solution to obtain the optimal distribution coefficient;

[0009] S5: Modify the optimal distribution coefficient according to the torque slope limit to obtain the torque distribution result of the four-wheel in-wheel motor-driven vehicle, and complete the torque distribution of the four-wheel in-wheel motor-driven vehicle considering the motor efficiency difference.

[0010] The beneficial effects of the above solution are as follows: By establishing the efficiency map model of the motor and combining the operating state information of the vehicle, the present invention distributes torque to each wheel in the most efficient driving manner on the premise of meeting the motion requirements. By considering the motor efficiency difference, more efficient energy utilization can be achieved, the driving range and energy utilization rate of the vehicle can be improved, and the problem that the traditional torque distribution method causes the motor to operate in the low-efficiency region due to ignoring the efficiency map between motors is solved.

[0011] Furthermore, S1 includes the following sub-steps:

[0012] S1-1: Calculate the motor speed ω according to the vehicle speed v of the four-wheel in-wheel motor-driven vehicle. The formula is:

[0013] ω = v / r w

[0014] where r w is the wheel radius;

[0015] S1-2: Interpolate and calculate the maximum torque T FL_max of the left front wheel motor, the maximum torque T FR_max of the right front wheel motor, the maximum torque T RL_max of the left rear wheel motor, and the maximum torque T RR_max of the right rear wheel motor. The formula is:

[0016] T FL_max = f T_FL (ω)

[0017] T FR_max = f T_FR (ω)

[0018] T RL_max = f T_RL (ω)

[0019] T RR_max = f T_RR (ω)

[0020] where f T_FL (·) is the external characteristic of the left front wheel motor, f T_FR (·) is the external characteristic of the right front wheel motor, f T_RL (·) is the external characteristic of the left rear wheel motor, f T_RR (·) is the external characteristic of the right rear wheel motor;

[0021] S1-3: Superimpose the maximum torque of the motor to obtain the maximum driving force T of the vehicle max , and the formula is:

[0022] T max = T FL_max + T FR_max + T RL_max + T RR_max .

[0023] The beneficial effect of the above further solution is: Through the above technical solution, according to the vehicle speed, motor speed, and the maximum torque of each wheel motor, the maximum driving force of the vehicle is obtained for subsequent calculations.

[0024] Furthermore, the total required torque T of the vehicle in S2 demand The formula is:

[0025] T demand = S pedal * T max

[0026] where S pedal is the pedal opening.

[0027] The beneficial effect of the above further solution is: Through the above technical solution, the total requirement of the vehicle is obtained based on the pedal opening and the maximum driving force of the vehicle.

[0028] Furthermore, the formula for the drive efficiency objective function and constraint conditions in S3 is:

[0029]

[0030] where min represents taking the minimum value, P bat_dem is the drive efficiency objective function, T FL is the torque of the left front wheel motor, T FR is the torque of the right front wheel motor, T RL is the torque of the left rear wheel motor, T RR is the torque of the right rear wheel motor, η FL is the efficiency of the left front wheel motor, η FR is the efficiency of the right front wheel motor, η RL is the efficiency of the left rear wheel motor, η RR is the efficiency of the right rear wheel motor, f η_FL (·) is the efficiency map characteristic of the left front wheel motor, f η_FR (·) is the efficiency map characteristic of the right front wheel motor, f η_RL (·) is the efficiency map characteristic of the left rear wheel motor, f η_RR (·) is the efficiency map characteristic of the right rear wheel motor, V oc is the battery open circuit voltage, I bat is the current, μ is the road adhesion coefficient, Fz_FL is the vertical load of the left front wheel motor, F z_FR is the vertical load of the right front wheel motor, F z_RL is the vertical load of the left rear wheel motor, F z_RR is the vertical load of the right rear wheel motor.

[0031] The beneficial effect of the above further solution is that in the constraint conditions, the total demand torque constraint, the maximum driving torque constraint, the efficiency constraint, the battery power constraint, the ground adhesion constraint, and the torque symmetric distribution on both sides are considered, ensuring the rationality of torque distribution.

[0032] Further, the optimal solution of torque distribution in S4 is simplified to calculate the optimal distribution coefficient according to the vehicle speed v and the total demand torque T of the vehicle under the constraint conditions demand , and the formula is:

[0033]

[0034] where λ 1opt (·) is the two-dimensional interpolation function of the first optimal distribution coefficient λ1, and λ 2opt (·) is the two-dimensional interpolation function of the second optimal distribution coefficient λ2.

[0035] The beneficial effect of the above further solution is that through the above technical solution, the optimal distribution of torque is transformed into the problem of calculating the optimal distribution coefficient, simplifying the calculation method.

[0036] Further, the calculation of λ 1opt (v, T demand ) and λ 2opt (v, T demand ) includes the following sub-steps:

[0037] S4-1: Divide the vehicle speed v into N equal intervals, divide the total demand torque T of the vehicle demand into M equal intervals, and establish a two-dimensional grid of the vehicle speed v and the total demand torque T of the vehicle demand ;

[0038] S4-2: According to the two-dimensional grid, calculate the optimal distribution coefficient under each combination of the vehicle speed v and the total demand torque T of the vehicle under the constraint conditions, and take the distribution coefficient corresponding to the minimum total demand torque T demand as λ demand (v, T 1opt ) and λ demand 2opt (v, T(v, T demand ).

[0039] The beneficial effects of the above further solution are as follows: In the optimization solution, through offline calculation, the best distribution coefficient at different speeds and different required torques is calculated by using the traversal method. When the vehicle is running, the best distribution coefficient can be determined only by online interpolation according to the vehicle speed and the required torque, which reduces the computational workload of the control unit.

[0040] Further, the specific method for correcting the best distribution coefficient in S5 is as follows:

[0041] λ 1opt_fix (·) is the corrected λ 1opt (v, T demand ), and the calculation results are as follows:

[0042]

[0043] Among them, is the partial derivative symbol, l is the wheelbase, ζ is the set allowable value, Δv is the vehicle speed change, and ΔT is the total required torque change of the vehicle;

[0044] λ 2opt_fix (·) is the corrected λ 2opt (v, T demand ), and the calculation results are as follows:

[0045]

[0046] The beneficial effects of the above further solution are as follows: During the actual vehicle operation, external uncertain environmental disturbances may cause fluctuations in the vehicle speed and the required torque, resulting in sudden changes in the best distribution coefficient, which in turn causes sudden changes in the total vehicle torque, generating vehicle motion shocks and reducing comfort. Therefore, the present invention proposes a method for correcting the best distribution coefficient based on the limitation of the directional derivative to ensure that the distributed torque is achievable and ensure the comfort of the four-wheel hub motor-driven vehicle.

[0047] Further, the torque distribution result of the four-wheel hub motor-driven vehicle in S5 is:

[0048]

[0049] Among them, is the torque distribution result of the left front wheel motor, is the torque distribution result of the right front wheel motor, is the torque distribution result of the left rear wheel motor, is the torque distribution result of the right rear wheel motor.

[0050] The beneficial effects of the above further solution are as follows: Through the above formula, the torque distribution results of the left front wheel motor, the right front wheel motor, the left rear wheel motor, and the right rear wheel motor are obtained, ensuring the best efficiency distribution of the four-wheel hub motor-driven vehicle during operation. Description of the Drawings

[0051] Figure 1 Flowchart of the torque distribution method for a four-wheel in-wheel motor-driven vehicle considering motor efficiency differences

[0052] Figure 2 External characteristic curves of four motors

[0053] Figure 3 Efficiency map curves of four motors

[0054] Figure 4 Equivalent model diagram of the battery

[0055] Figure 5 Internal resistance characteristic curve of the battery

[0056] Figure 6 Open-circuit voltage characteristic curve of the battery

[0057] Figure 7 Optimal distribution coefficient λ 1opt (v, T demand ) and λ 2opt (v, T demand ) Solving result diagram

[0058] Figure 8 Optimal distribution coefficient λ 1opt (v, T demand ) and λ 2opt (v, T demand ) Revised solving result diagram Detailed Implementation Manner

[0059] The present invention will be further described below in conjunction with the drawings and specific embodiments

[0060] As Figure 1 shown, a torque distribution method for a four-wheel in-wheel motor-driven vehicle considering motor efficiency differences includes the following steps

[0061] S1: Obtain the maximum driving force of the vehicle according to the vehicle speed of the four-wheel in-wheel motor-driven vehicle

[0062] S2: Obtain the total required torque of the vehicle according to the maximum driving force of the vehicle and the pedal opening

[0063] S3: Based on the total required torque of the vehicle, establish a driving efficiency objective function and constraint conditions

[0064] S4: According to the driving efficiency objective function and constraint conditions, perform torque distribution optimization to obtain the optimal distribution coefficient

[0065] S5: Modify the optimal distribution coefficient according to the torque slope limit to obtain the torque distribution result of the four-wheel in-wheel motor-driven vehicle, and complete the torque distribution of the four-wheel in-wheel motor-driven vehicle considering the motor efficiency difference.

[0066] S1 includes the following sub-steps:

[0067] S1-1: Calculate the motor speed ω based on the vehicle speed v of the four-wheel in-wheel motor-driven vehicle. The formula is:

[0068] ω = v / r w

[0069] where r w is the wheel radius;

[0070] S1-2: Interpolate and calculate the maximum torque T FL_max of the left front wheel motor, the maximum torque T FR_max of the right front wheel motor, the maximum torque T RL_max of the left rear wheel motor, and the maximum torque T RR_max of the right rear wheel motor. The formula is:

[0071] T FL_max = f T_FL (ω)

[0072] T FR_max = f T_FR (ω)

[0073] T RL_max = f T_RL (ω)

[0074] T RR_max = f T_RR (ω)

[0075] where f T_FL (·) is the external characteristic of the left front wheel motor, f T_FR (·) is the external characteristic of the right front wheel motor, f T_RL (·) is the external characteristic of the left rear wheel motor, f T_RR (·) is the external characteristic of the right rear wheel motor, as Figure 2 shown;

[0076] S1-3: Superimpose the maximum motor torques to obtain the maximum driving force T max of the vehicle. The formula is:

[0077] T max = T FL_max + T FR_max + T RL_max + T RR_max .

[0078] Total vehicle demand torque T in S2 demand The formula is:

[0079] T demand = S pedal * T max

[0080] Where S pedal is the pedal opening (ranging from 0 to 1).

[0081] The formula for the drive efficiency objective function and constraint conditions in S3 is:

[0082] During vehicle driving, the drive efficiency objective function is:

[0083]

[0084] Constraint condition 1, satisfying the total demand torque constraint:

[0085] T demand = T FL + T FR + T RL + T RR

[0086] Constraint condition 2, the maximum drive torque constraint of the four motors. That is, the torques of the four motors should be less than the maximum values of their respective motors:

[0087]

[0088] Constraint condition 3, the efficiency constraint of the four motors:

[0089]

[0090] f η_FL (·), f η_FR (·), f η_RL (·), f η_RR (·) represent the motor efficiency map characteristics of the left front wheel motor, right front wheel motor, left rear wheel motor, and right rear wheel motor respectively, as Figure 3 shown;

[0091] Constraint condition 4, the battery power constraint: The driving energy of the four-wheel hub motors comes from the battery. In the battery, a first-order equivalent circuit model is used to simulate the charging and discharging process of the battery, as Figure 4 shown. According to Kirchhoff's principle, the current I bat The calculation formula is as follows:

[0092]

[0093] Where V oc is the open-circuit voltage of the battery, R intis the internal resistance. In this embodiment, the internal resistance characteristic is as Figure 5 shown, where P bat_req is the load power;

[0094] The battery SOC b (t) is estimated by the ampere-hour integration method as:

[0095]

[0096] where SOC b (t0) is the initial value of the battery, Q max is the maximum capacity of the battery, t0 is the initial time, and t is the current time;

[0097] The open-circuit voltage V oc of the battery and the battery SOC b (t) have a certain functional relationship, which is obtained through experiments. In this embodiment, the functional relationship between V oc and SOC b (t) is as Figure 6 shown:

[0098] V oc = f soc_v (SOC b (t))

[0099] where f soc_v (·) is a non-linear function of the voltage varying with SOC b (t);

[0100] Then the output power of the battery satisfies:

[0101] P bat_dem ≤ V oc I bat

[0102] Constraint 5, the torque symmetry distribution constraint on both sides of the vehicle. This constraint mainly ensures that after torque distribution, the vehicle does not deviate, that is, it should satisfy that the torque distributed on the left side is equal to the torque on the right side:

[0103] T FL + T RL = T FR + T RR

[0104] Constraint 6, the ground longitudinal force generated by the distributed motor torque is less than the ground adhesion force:

[0105]

[0106]

[0107] Among them, m is the vehicle mass, g is the acceleration due to gravity, b is the distance from the center of mass to the front axle, l is the wheelbase, and h g is the height of the center of mass, B is the track width, and a x is the longitudinal acceleration, and a y is the lateral acceleration.

[0108] In summary, the torque distribution problem of a four-wheel in-wheel motor-driven vehicle considering the difference in the motor efficiency map can be abstracted as a typical optimization problem. The optimization objective function and constraints are as follows:

[0109]

[0110] Among them, min represents taking the minimum value, and P bat_dem is the drive efficiency objective function, T FL is the torque of the left front wheel motor, T FR is the torque of the right front wheel motor, T RL is the torque of the left rear wheel motor, T RR is the torque of the right rear wheel motor, η FL is the efficiency of the left front wheel motor, η FR is the efficiency of the right front wheel motor, η RL is the efficiency of the left rear wheel motor, η RR is the efficiency of the right rear wheel motor, f η_FL (·) is the efficiency map characteristic of the left front wheel motor, f η_FR (·) is the efficiency map characteristic of the right front wheel motor, f η_RL (·) is the efficiency map characteristic of the left rear wheel motor, f η_RR (·) is the efficiency map characteristic of the right rear wheel motor, V oc is the battery open-circuit voltage, and I bat is the current, μ is the road adhesion coefficient, and F z_FL is the vertical load of the left front wheel motor, F z_FR is the vertical load of the right front wheel motor, F z_RL is the vertical load of the left rear wheel motor, F z_RR is the vertical load of the right rear wheel motor.

[0111] In S4, the torque distribution optimization solution is simplified to calculate the optimal distribution coefficient according to the vehicle speed v and the total vehicle demand torque T demand , and the formula is:

[0112]

[0113] Among them, λ 1opt (·) is the two-dimensional interpolation function of the first optimal distribution coefficient λ1, and λ 2opt (·) is the two-dimensional interpolation function of the second optimal distribution coefficient λ2;

[0114] λ 1opt (v, T demand ) and λ 2opt (v, T demand ) are calculated in the following sub - steps:

[0115] S4 - 1: Divide the vehicle speed v into N equal intervals, divide the total vehicle demand torque T demand into M equal intervals, and establish a two - dimensional grid of the vehicle speed v and the total vehicle demand torque T demand ;

[0116] In this embodiment, the vehicle speed v is divided into T is divided into demand ; v max is the maximum vehicle speed, and both N and M are positive integers greater than 3. The larger N and M are, the finer the division is;

[0117] S4 - 2: According to the two - dimensional grid, calculate the optimal distribution coefficient for each combination of the vehicle speed v and the total vehicle demand torque T demand under the condition of meeting the constraint conditions, and take the distribution coefficient corresponding to the minimum total demand torque T demand as λ 1opt (v, T demand ) and λ 2opt (v, T demand ). In this embodiment, the solution results of the optimal distribution coefficients obtained by traversing are as shown in Figure 7 ;

[0118] In an embodiment of the present invention, according to the optimal distribution coefficient λ 1opt (v, T demand ) obtained in S4, λ 2opt (v, T demand ) is only the theoretically optimal distribution coefficient. Then, during the actual vehicle operation, for example, due to external uncertain environmental disturbances, the vehicle speed v may have slight fluctuations, and the total vehicle demand torque T demand may fluctuate due to the fluctuation of the accelerator pedal. If v and T demand have slight fluctuations, the optimal distribution coefficients at the previous moment and the next moment may mutate. However, the actual motor torque response requires a certain time. The sudden change in the demand torque within a short period may cause the actual torque to fail to respond in time, resulting in a sudden change in the total vehicle torque and thus reducing the comfort of the vehicle due to vehicle motion shock. Therefore, it is also necessary to appropriately correct the solved distribution coefficients in the two - dimensional space formed by v and T demand . To solve this problem, the present invention introduces a torque slope limit. When in the two - dimensional space formed by v and T demand , respectively, λ1 with respect to v and T demandFind the directional derivative. When the absolute value of the directional derivative is greater than the allowable value ζ (a positive integer), then take ζ.

[0119] The specific method for correcting the optimal distribution coefficient in S5 is as follows:

[0120] λ 1opt_fix (·) is the corrected λ 1opt (v, T demand ), and the calculation results are as follows:

[0121]

[0122] Among them, is the partial derivative symbol, ζ is the set allowable value, Δv is the vehicle speed change, and ΔT is the change in the total demand torque of the vehicle;

[0123] λ 2opt_fix (·) is the corrected λ 2opt (v, T demand ), and the calculation results are as follows:

[0124]

[0125] In this embodiment, the correction result is as Figure 8 shown.

[0126] The torque distribution result of the four-wheel in-wheel motor drive vehicle in S5 is:

[0127]

[0128] Among them, is the torque distribution result of the left front wheel motor, is the torque distribution result of the right front wheel motor, is the torque distribution result of the left rear wheel motor, is the torque distribution result of the right rear wheel motor.

[0129] The present invention proposes a torque distribution method for a four-wheel in-wheel motor drive vehicle considering the difference of the motor efficiency map. By considering the motor efficiency difference, more efficient energy utilization can be achieved, and the vehicle's cruising range and energy utilization rate can be improved.

[0130] Those of ordinary skill in the art will realize that the embodiments described herein are for helping readers understand the principles of the present invention and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations without departing from the essence of the present invention according to the technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the invention.

Claims

1. A torque distribution method for a four-wheel in-wheel motor drive vehicle considering the difference in motor efficiency, characterized in that It includes the following steps: S1: Obtain the maximum driving force of the vehicle according to the vehicle speed of the four-wheel in-wheel motor-driven vehicle; S2: Obtain the total required torque of the vehicle according to the maximum driving force of the vehicle and the pedal opening; S3: Based on the total required torque of the vehicle, establish a driving efficiency objective function and constraints; S4: According to the driving efficiency objective function and constraints, perform torque distribution optimization to obtain the optimal distribution coefficient; S5: According to the torque slope limit, correct the optimal distribution coefficient to obtain the torque distribution result of the four-wheel in-wheel motor-driven vehicle, and complete the torque distribution of the four-wheel in-wheel motor-driven vehicle considering the motor efficiency difference; The formulas of the driving efficiency objective function and constraints in S3 are: Among them, represents taking the minimum value, is the driving efficiency objective function, is the torque of the left front wheel motor, is the torque of the right front wheel motor, is the torque of the left rear wheel motor, is the torque of the right rear wheel motor, is the motor speed, is the efficiency of the left front wheel motor, is the efficiency of the right front wheel motor, is the efficiency of the left rear wheel motor, is the efficiency of the right rear wheel motor, is the total vehicle demand torque, is the maximum torque of the left front wheel motor, is the maximum torque of the right front wheel motor, is the maximum torque of the left rear wheel motor, is the maximum torque of the right rear wheel motor, is the efficiency map characteristic of the left front wheel motor, is the efficiency map characteristic of the right front wheel motor, is the efficiency map characteristic of the left rear wheel motor, is the efficiency map characteristic of the right rear wheel motor, is the battery open-circuit voltage, is the current, is the wheel radius, is the road surface adhesion coefficient, is the vertical load of the left front wheel motor, is the vertical load of the right front wheel motor, is the vertical load of the left rear wheel motor, is the vertical load of the right rear wheel motor; The torque distribution optimization solution in S4 is simplified to calculate the optimal distribution coefficient according to the vehicle speed and the total vehicle demand torque , and the formula is: Among them, is the two-dimensional interpolation function of the first optimal allocation coefficient , is the two-dimensional interpolation function of the second optimal allocation coefficient ; The said and calculation includes the following sub-steps: S4-1: Divide the vehicle speed into N equal intervals, divide the total vehicle demand torque into M equal intervals, and establish a two-dimensional grid of vehicle speed and total vehicle demand torque ; S4-2: Calculate each vehicle speed under the condition of satisfying the constraint conditions according to the two-dimensional grid and the total demand torque of the vehicle Under the combination, calculate the optimal distribution coefficient, and use the distribution coefficient corresponding to the minimum total demand torque as and ; The specific method for correcting the optimal distribution coefficient in S5 is: For the revised , the calculation results are as follows: Among them, is the partial derivative symbol, is the wheelbase, is the set allowable value, is the vehicle speed change amount, is the total vehicle demand torque change amount; For the revised , the calculation results are as follows: 。 2. The torque distribution method for a four-wheel in-wheel motor-driven vehicle considering the motor efficiency difference according to claim 1, wherein The following sub-steps are included in S1: S1-1: According to the vehicle speed of a four-wheel in-wheel motor drive vehicle calculate the motor speed , the formula is: Among them, is the wheel radius; S1-2: According to the motor speed Interpolate and calculate the maximum torque of the left front wheel motor , the maximum torque of the right front wheel motor , the maximum torque of the left rear wheel motor and the maximum torque of the right rear wheel motor , the formula is: Among them, is the external characteristic of the left front wheel motor, is the external characteristic of the right front wheel motor, is the external characteristic of the left rear wheel motor, is the external characteristic of the right rear wheel motor; S1-3: Superimpose the maximum torque of the motor to obtain the maximum driving force of the vehicle , and the formula is: 。 3. The torque distribution method for a four-wheel in-wheel motor-driven vehicle considering the difference in motor efficiency according to claim 2, characterized in that The total vehicle demand torque in S2 The formula is: Among them, is the pedal opening degree.

4. The torque distribution method for a four-wheel in-wheel motor drive vehicle considering the motor efficiency difference according to claim 1, characterized in that, The torque distribution result of the four-wheel in-wheel motor-driven vehicle in S5 is: Among them, is the torque distribution result of the left front wheel motor, is the torque distribution result of the right front wheel motor, is the torque distribution result of the left rear wheel motor, is the torque distribution result of the right rear wheel motor.

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