Distributed four-motor drive redundancy control method and system
By constructing a multi-objective cost function to optimize the redistribution of driving torque, the driving stability and safety issues of distributed drive electric vehicles in the event of motor failure are solved, and fast and accurate torque adjustment and energy consumption optimization are achieved.
Patent Information
- Application Number
- CN202610538487.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-22
- Publication Date
- 2026-07-24
AI Technical Summary
In distributed drive electric vehicles, when some motors fail or their capabilities are degraded, torque redistribution cannot be carried out in a timely and reasonable manner, affecting vehicle driving stability and safety.
By constructing a multi-objective cost function, including torque adjustment cost, system efficiency cost, and motor reserve capacity cost, the drive torque redistribution is optimized to meet the hard constraints of longitudinal drive and yaw differential, thus ensuring vehicle safety and stability.
When a single motor malfunctions, the target torque of each normal motor can be quickly and accurately determined to ensure the safety and stability of vehicle operation, while taking into account torque adjustment time, system energy consumption and motor capacity reserves.
Smart Images
Figure CN122443232A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of vehicle drive control technology, and in particular to a distributed four-motor drive redundancy control method and system. Background Technology
[0002] Distributed drive electric vehicles are equipped with independently driven wheel-side or hub motors for each wheel, eliminating the need for mechanical connections such as drive shafts and differentials. This results in advantages such as compact structure, high transmission efficiency, and flexible control. However, distributed drive systems are redundant drive systems containing multiple actuators. If some motors fail or their capabilities degrade, and torque redistribution is not performed promptly and appropriately, it will directly affect the vehicle's driving stability and safety. Summary of the Invention
[0003] The embodiments of this application provide a distributed four-motor drive redundancy control method, system, device and storage medium, which can optimize the redistribution of drive torque under the premise of satisfying the hard constraints of longitudinal drive and yaw differential when some motors fail or their capabilities are degraded, thereby ensuring the driving safety and stability of the vehicle.
[0004] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.
[0005] This application specifically includes the following aspects: In a first aspect, this application proposes a distributed four-motor drive redundancy control method, applied to a distributed drive system, the distributed drive system comprising four motors, the method comprising: Based on the driver's acceleration and steering actions, the vehicle's longitudinal torque demand and yaw differential torque are determined. If the motor fault information of the vehicle indicates a single motor abnormality, then a multi-objective cost function is constructed based on multiple of the original required torque, motor speed, and torque capacity limit of each motor. The multi-objective cost function includes multiple of the torque adjustment cost sub-function, system efficiency cost sub-function, and motor reserve capacity cost sub-function. The target torque of each normal motor is determined based on the multi-objective cost function, the longitudinal demand torque, and the yaw differential torque, and the corresponding normal motor is controlled to perform drive output according to the target torque.
[0006] In one feasible implementation, determining the target torque of each normal motor based on the multi-objective cost function, the longitudinal demand torque, and the yaw differential torque includes: The sum of the target torques of the two normal motors on the opposite side of the abnormal motor is determined as the average of the difference between the longitudinal required torque and the yaw differential torque; The target torque of one of the normal motors on the opposite side of the abnormal motor is determined based on the multi-objective cost function; Based on the average value of the difference between the longitudinal demand torque and the yaw differential torque, and the target torque of one of the normal motors on the opposite side of the abnormal motor, the target torque of the other normal motor on the opposite side of the abnormal motor is determined.
[0007] In one feasible implementation, determining the target torque of one of the normal motors on the opposite side of the abnormal motor based on the multi-objective cost function includes: Determine the feasible region of the free variables in the multi-objective cost function; Based on the absolute value inflection point in the torque adjustment cost sub-function and the efficiency segmentation point in the system efficiency cost sub-function, the feasible region is divided into several sub-intervals; Obtain the minimum cost value of the multi-objective cost function in each sub-interval; Compare the minimum value corresponding to all sub-intervals, and determine the sub-interval corresponding to the minimum value with the smallest value as the optimal interval; Within the optimal range, the optimal value of the free variable is selected as the target torque of one of the normal motors based on the minimum torque adjustment cost.
[0008] In one feasible implementation, obtaining the minimum cost value of the multi-objective cost function in each sub-interval includes: If the multi-objective cost function is a constant within the sub-interval, then the constant is taken as the minimum cost value; If the multi-objective cost function within the sub-interval is a monotonic function, then the multi-objective cost function values at the two endpoints of the sub-interval are obtained, and the minimum value among the multi-objective cost function values at the two endpoints is taken as the minimum cost value.
[0009] In one feasible implementation, determining the target torque of each normal motor based on the multi-objective cost function, the longitudinal demand torque, and the yaw differential torque further includes: If a single motor malfunctions as a complete failure of that single motor, the target torque of the normal motor on the same side as the malfunctioning motor is determined as the average of the sum of the longitudinal required torque and the yaw differential torque. If a single motor malfunction is a degradation of the single motor's capacity and the original required torque of the malfunctioning motor is greater than the degradation capacity limit of the malfunctioning motor, then the target torque of the malfunctioning motor is determined as the degradation capacity limit. Based on the average value of the sum of the longitudinal demand torque and the yaw differential torque, and the degradation capability limit, the target torque of the normal motor on the same side as the abnormal motor is determined.
[0010] In one feasible implementation, after determining the target torque of the normal motor on the same side as the abnormal motor as the average of the sum of the longitudinal demand torque and the yaw differential torque, the method further includes: If a single motor malfunction is a complete failure of that single motor, and the target torque of the normal motor on the same side as the malfunctioning motor is greater than the torque capability limit of the normal motor on the same side as the malfunctioning motor or the road surface adhesion capability limit of the wheel where the normal motor on the same side as the malfunctioning motor is located, then the target torque of the normal motor on the same side as the malfunctioning motor is corrected to the minimum value between the torque capability limit and the road surface adhesion capability limit.
[0011] In one feasible implementation, the multi-objective cost function is obtained by weighted summation of the torque adjustment cost sub-function, the system efficiency cost sub-function, and the motor reserve capacity cost sub-function, wherein the weight coefficients of the torque adjustment cost sub-function, the system efficiency cost sub-function, and the motor reserve capacity cost sub-function are obtained in the following manner: If a motor failure occurs for the first time, the weight coefficient of the torque adjustment cost subfunction is set to 1, and the weight coefficients of the system efficiency cost subfunction and the motor reserve capacity cost subfunction are set to 0. After the normal motor is controlled to perform drive output according to the target torque, the weight coefficients are adjusted according to the road condition type and driving mode.
[0012] In one feasible implementation, it further includes: If the motor fault information indicates that both motors have completely failed, then the sum of the target torques of the two motors on the non-failed side is set as the longitudinal required torque, and the difference between the target torques of the two motors on the non-failed side is set as the yaw differential torque. If the motor fault information indicates a degradation in the capability of the two motors on the same side, then the difference in target torque between the two motors on the degraded side is set as the yaw differential torque, the sum of target torques of the two motors on the degraded side is set as the minimum value among the total capability limit of the two motors on the degraded side and the average of the sum of the longitudinal demand torque and the yaw differential torque, the sum of target torques of the two motors on the non-degraded side is set as the longitudinal demand torque minus the sum of target torques of the two motors on the degraded side, and the difference in target torques of the two motors on the non-degraded side is set as the yaw differential torque minus the difference in target torques of the two motors on the degraded side. If the motor fault information indicates a degradation in the capability of the coaxial dual motors, then the sum of the target torques of the two motors on the degraded shaft is set to the minimum value between the total capability limit of the two motors on the degraded shaft and the longitudinal required torque; the difference between the target torques of the two motors on the degraded shaft is set to the first preset ratio value of the yaw differential torque; the sum of the target torques of the two motors on the non-degraded shaft is set to the longitudinal required torque minus the sum of the target torques of the two motors on the degraded shaft; and the difference between the target torques of the two motors on the non-degraded shaft is set to the yaw differential torque minus the difference between the target torques of the two motors on the degraded shaft. If the motor fault information indicates a degradation in the capability of the cross-axis dual motors, then the target torques of the two motors on the degradation side are set to their respective degradation capability limits, the sum of the target torques of the two motors on the non-degraded side is set to the longitudinal required torque minus the sum of the target torques of the two motors on the degradation side, and the difference in the target torques of the two motors on the non-degraded side is set to the yaw differential torque minus the difference in the target torques of the two motors on the degradation side.
[0013] In one feasible implementation, it further includes: Based on the external characteristic capability limits of each motor and the driving capability limits of the distributed drive system, the torque capability limits of each motor are determined. Based on the vehicle's longitudinal acceleration, lateral acceleration, and wheel loads, the road adhesion limit for each wheel is determined.
[0014] Secondly, this application also proposes a distributed four-motor drive redundancy control system, comprising: The data acquisition unit is used to determine the vehicle's longitudinal torque demand and yaw differential torque based on the driver's acceleration and steering operations. The function construction unit is used to construct a multi-objective cost function based on multiple of the original required torque, motor speed, and torque capacity limit of each motor if the motor fault information of the vehicle indicates a single motor abnormality. The multi-objective cost function includes multiple of the torque adjustment cost sub-function, system efficiency cost sub-function, and motor reserve capacity cost sub-function. The torque control unit is used to determine the target torque of each normal motor based on the multi-objective cost function, the longitudinal demand torque, and the yaw differential torque, and to control the corresponding normal motor to perform drive output according to the target torque.
[0015] This application proposes a distributed four-motor drive redundancy control method. By constructing a multi-objective cost function that includes torque adjustment cost, system efficiency cost, and motor reserve capacity cost, it takes into account torque adjustment time (i.e., response speed), system energy consumption (i.e., drive efficiency), and motor capacity reserve (i.e., avoiding overload and ensuring power margin) under the premise of satisfying the hard constraints of longitudinal drive and yaw differential. Thus, while ensuring the safety and stability of vehicle driving, it can quickly and accurately determine the target torque of each normal motor when a single motor is abnormal.
[0016] This application proposes a distributed four-motor drive redundancy control method and system. Other advantages, objectives and features of this application will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this application. Attached Figure Description
[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit this specification. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart illustrating a distributed four-motor drive redundancy control method provided in an embodiment of this application; Figure 2 A function curve of a torque adjustment cost sub-function provided in an embodiment of this application; Figure 3 This application provides a schematic diagram of the functional modules of a distributed four-motor drive redundancy control system. Figure 4 This is a schematic diagram of a distributed four-motor drive redundancy control device provided in an embodiment of this application. Detailed Implementation
[0018] To better understand the technical solutions provided in the embodiments of this specification, the technical solutions of the embodiments of this specification will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this specification and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this specification, rather than limitations on the technical solutions of this specification. In the absence of conflict, the embodiments of this specification and the technical features in the embodiments can be combined with each other.
[0019] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The term "two or more" includes two or more cases.
[0020] This application provides a distributed four-motor drive redundancy control method, applied to a distributed drive system comprising four motors. (See also...) Figure 1 , Figure 1 A flowchart illustrating a distributed four-motor drive redundancy control method provided in this application embodiment may specifically include: S110. Based on the driver's acceleration and steering operations, determine the vehicle's longitudinal torque demand and yaw differential torque.
[0021] For example, firstly, the vehicle controller acquires the driver's accelerator pedal opening and steering wheel angle in real time, and combines this with the current vehicle speed to obtain the required longitudinal torque by looking up a table. Simultaneously, based on the deviation between the target yaw rate and the actual yaw rate, PID control (Proportional-Integral-Derivative) is performed to calculate the yaw differential torque. .
[0022] S120. If the vehicle's motor fault information indicates a single motor abnormality, then a multi-objective cost function is constructed based on multiple of the original required torque, motor speed, and torque capability limit of each motor. The multi-objective cost function includes multiple of the torque adjustment cost sub-function, system efficiency cost sub-function, and motor reserve capacity cost sub-function.
[0023] For example, when the system diagnoses an anomaly in a motor (e.g., the front left motor), the controller reads the original torque demand of each motor before the fault. (For example, the requirement before the left front motor failure was 100 Nm), the current speed of each motor, and the torque capacity limit of each motor. Based on these parameters, the controller constructs a multi-objective cost function, which includes a torque adjustment cost subfunction J1, a system efficiency cost subfunction J2, and a motor reserve capacity cost subfunction J3.
[0024] S130: Determine the target torque of each normal motor based on the multi-objective cost function, longitudinal demand torque, and yaw differential torque, and control the corresponding normal motor to perform drive output according to the target torque.
[0025] For example, the controller utilizes a multi-objective cost function, combined with a determined longitudinal torque demand. and yaw differential torque The target torque of each normal motor is calculated, and finally the corresponding motor is controlled to perform drive output according to these target torques, thereby realizing redundant drive in the case of single motor abnormality.
[0026] In some examples, the target torque for each normal motor is determined based on a multi-objective cost function, longitudinal demand torque, and yaw differential torque, including: The sum of the target torques of the two normal motors on the opposite side of the abnormal motor is determined as the average of the difference between the longitudinal demand torque and the yaw differential torque. The target torque of one of the normal motors on the opposite side of the abnormal motor is determined based on a multi-objective cost function. Based on the average difference between the longitudinal demand torque and the yaw differential torque, and the target torque of one of the normal motors on the opposite side of the abnormal motor, determine the target torque of the other normal motor on the opposite side of the abnormal motor.
[0027] For example, in the case of a single motor malfunction (taking the failure of the left front motor as an example), the controller first uses the lateral and longitudinal dynamic constraint equations. and Obtain the total demand torque on the left and the total demand torque on the right. Solve this system of equations to obtain the total demand torque on the left. Total torque demand on the right side When the left front motor When a fault occurs, the following conditions should be met according to the aforementioned formula: ; ; in, , , These are the target torques for the left rear, right front, and right rear motors, respectively. Due to the left front motor... Complete failure, with a target torque of 0, leaving only the left rear motor usable on the left side. Therefore, the target torque of the normal motor (left rear) on the same side as the malfunctioning motor (left front) is directly determined as: ; On the right side, there are two normal motors (front right). and right rear Their total demand must be met That is, the sum of the target torques of the front right and the rear right equals Therefore, the sum of the target torques of the two normal motors on the opposite side of the abnormal motor is determined as the average of the difference between the longitudinal demand torque and the yaw differential torque, that is: ; Then, to further optimize the allocation while satisfying the constraints, the controller uses the target torque of one of the motors (e.g., the right front motor) as the free variable x, and performs optimization based on a multi-objective cost function (including torque adjustment cost, system efficiency cost, and motor reserve capacity cost) to find the x value that minimizes the overall cost, which is then used as the target torque of the right front motor. Finally, the sum of the target torques of the two motors on opposite sides is used as the target torque. Given the already determined target torque x of the right front motor, the target torque of the other motor (right rear) is obtained by subtraction. In this way, the target torque of all normal motors is uniquely determined.
[0028] In some examples, the target torque of one of the normal motors on the opposite side of the abnormal motor is determined based on a multi-objective cost function, including: Determine the feasible region of the free variables in the multi-objective cost function; Based on the absolute value inflection point in the torque adjustment cost sub-function and the efficiency segmentation point in the system efficiency cost sub-function, the feasible region is divided into several sub-intervals. Obtain the minimum cost value of the multi-objective cost function in each sub-interval; Compare the minimum cost values corresponding to all subintervals, and determine the subinterval corresponding to the minimum cost value with the smallest value as the optimal interval; Within the optimal range, the optimal value of the free variable is selected as the target torque for one of the normal motors based on the minimum torque adjustment cost.
[0029] For example, taking the failure of the left front motor as an example, in order to determine the target torque of one of the normal motors (such as the right front motor) on the opposite side of the faulty motor based on a multi-objective cost function, the controller adopts a piecewise linear optimization strategy. First, the feasible region of the free variable x (i.e., the target torque of the right front motor) is determined according to the torque capability limit of the right front motor and the road adhesion capability limit of the right front wheel. Then, identify the absolute value inflection point in the torque adjustment cost sub-function (i.e., the point after converting the original required torque of the right front motor and the original required torque of the right rear motor) and the efficiency segmentation point in the system efficiency cost sub-function (i.e., the boundary torque values of different efficiency intervals in the efficiency MAP). Use these points to divide the feasible region into several sub-intervals, such as [ ]、[ ]、[ ], so that within each subinterval All are linear functions. Next, the minimum cost value within each subinterval is calculated. The minimum cost values of all subintervals are compared, and the subinterval corresponding to the minimum cost value with the smallest value is selected as the optimal interval. Finally, within this optimal range, to minimize the torque adjustment time, the minimum torque adjustment cost (e.g., ...) is used. The optimal value of the free variable x is selected as the target torque of the right front motor based on the principle that J1 is minimized.
[0030] In some examples, the minimum cost value of the multi-objective cost function is obtained within each sub-interval, including: If the multi-objective cost function within a sub-interval is a constant, then the constant is taken as the minimum cost. If the multi-objective cost function within the sub-interval is a monotonic function, then obtain the multi-objective cost function values at the two endpoints of the sub-interval, and take the minimum value among the multi-objective cost function values at the two endpoints as the minimum cost value.
[0031] For example, when obtaining the minimum cost value within each sub-interval, the controller first determines the linearity of the multi-objective cost function within that interval. If the multi-objective cost function is constant throughout the sub-interval, then that constant is taken as the minimum cost value for that sub-interval. If the multi-objective cost function is monotonic (i.e., linearly increasing or decreasing within the sub-interval), then the multi-objective cost function values at the left and right endpoints of the sub-interval are calculated separately, and the minimum of these two endpoint values is taken as the minimum cost value for that sub-interval.
[0032] In some examples, the target torque for each normal motor is determined based on a multi-objective cost function, longitudinal demand torque, and yaw differential torque. Other examples include: If a single motor malfunctions due to complete failure of that single motor, the target torque of the normal motor on the same side as the malfunctioning motor will be determined as the average of the sum of the longitudinal demand torque and the yaw differential torque. If a single motor malfunction is a degradation of the single motor's capacity and the original required torque of the malfunctioning motor is greater than the degradation capacity limit of the malfunctioning motor, then the target torque of the malfunctioning motor is determined as the degradation capacity limit. Based on the average value of the sum of longitudinal demand torque and yaw differential torque, and the degradation capability limit, the target torque of the normal motor on the same side as the abnormal motor is determined.
[0033] For example, when the specific type of single motor malfunction is complete failure (e.g., the left front motor is completely damaged and cannot output torque), the controller will directly determine the target torque of the normal motor (left rear motor) on the same side as the malfunctioning motor as the average of the sum of the longitudinal demand torque and the yaw differential torque.
[0034] When a single motor malfunctions due to capacity degradation (e.g., the capacity limit of the left front motor after degradation is...), =50Nm, while the original torque requirement before the failure was... (100Nm) The controller first determines whether the original torque demand of the degraded motor exceeds its degraded capability limit. If the original torque demand does not exceed the degraded capability limit, the torque demand of the four wheels is distributed according to the normal four-wheel drive distribution method, for example... The ability limit after being downgraded is When the original torque demand Not exceeding the downgrade capability limit At this time, the normal four-wheel drive distribution request is followed, meaning redundant control is not activated. If the original required torque exceeds the degradation capability limit (e.g., 100Nm > 50Nm), the controller sets the target torque of the abnormal motor to this degradation capability limit. = =50Nm, the lost torque (50Nm) is compensated by other normal motors. Then, according to the lateral and longitudinal dynamic constraint equations, the target torque of the degraded motor is... The sum of the target torques of the other three normal motors satisfies the longitudinal torque requirement: Furthermore, the sum of the target torques of the degraded motor and the normal motor on the same side, minus the sum of the torques of the two motors on opposite sides, equals the yaw differential torque. Therefore, the target torque of the normal motor (left rear motor) on the same side as the malfunctioning motor is: This is the average of the sum of the longitudinal demand torque and the yaw differential torque, minus the degradation capability limit. Meanwhile, the sum of the target torques of the two normal motors on opposite sides (right front and right rear) still meets the requirement. ,Right now The process is the same as in the case of complete failure. Subsequently, the controller optimizes the calculation of the target torque of one of the motors on the opposite side (e.g., the right front motor) based on a multi-objective cost function, and then subtracts this value from the sum to obtain the target torque of the other motor (right rear). In this way, the target torque of all normal motors is uniquely determined, and the torque lost by the degraded motors is compensated.
[0035] In some examples, after determining the target torque of the normal motor on the same side as the malfunctioning motor as the average of the sum of the longitudinal demand torque and the yaw differential torque, the method further includes: If a single motor malfunctions as a complete failure of the single motor, and the target torque of the normal motor on the same side as the malfunctioning motor is greater than the torque capacity limit of the normal motor on the same side as the malfunctioning motor or the road surface adhesion limit of the wheel where the normal motor on the same side as the malfunctioning motor is located, then the target torque of the normal motor on the same side as the malfunctioning motor will be corrected to the minimum of the torque capacity limit and the road surface adhesion limit.
[0036] For example, in the event of a complete failure of a single motor (e.g., the front left motor) and the target torque of the normal motor on the same side as the faulty motor (i.e., the target torque of the rear left motor) has been set. After initially setting the target torque as the average of the sum of the longitudinal demand torque and the yaw differential torque, the controller needs to perform a safety check on this value. Specifically, the controller determines whether the target torque exceeds the torque capacity limit of the normal motor on the same side (e.g., the maximum capacity limit of the left rear motor). ) or the road adhesion limit of the wheel where the motor is located (e.g., the road adhesion limit of the left rear wheel). If the target torque does not exceed the two limits mentioned above, the original value remains unchanged. If the target torque exceeds either limit, the controller corrects the target torque of the normal motor on the same side to the minimum of the two limits, that is, takes the smaller of the torque capability limit and the road adhesion capability limit as the new target torque (e.g., After the correction, the original longitudinal torque requirement and yaw differential torque constraints will no longer be met. Therefore, the controller needs to recalculate the sum and difference of the target torques of the two motors on opposite sides based on the corrected target torque of the motor on the same side.
[0037] In some examples, the multi-objective cost function is obtained by a weighted sum of the torque adjustment cost subfunction, the system efficiency cost subfunction, and the motor reserve capacity cost subfunction. The weight coefficients of the torque adjustment cost subfunction, the system efficiency cost subfunction, and the motor reserve capacity cost subfunction are obtained in the following way: If a motor failure occurs for the first time, the weight coefficient of the torque adjustment cost subfunction is set to 1, and the weight coefficients of the system efficiency cost subfunction and the motor reserve capacity cost subfunction are set to 0. After controlling the corresponding normal motor to execute drive output according to the target torque, the weight coefficients are adjusted according to the road condition type and driving mode.
[0038] For example, the multi-objective cost function is obtained by weighted summation of the torque adjustment cost sub-function, the system efficiency cost sub-function, and the motor reserve capacity cost sub-function, where: Torque adjustment cost sub-function J1 calculation: When a single motor fails, its torque capability decreases or becomes zero, disrupting the current balance between longitudinal torque demand and yaw differential torque, and even causing unexpected yaw motion, affecting driving safety. Therefore, the ability to quickly reach a new dynamic balance is an important indicator for evaluating the merits of the allocation scheme, quantified by the torque adjustment cost sub-function J1. The torque adjustment amount for each motor is defined as follows: ,in, The target torque for each normal motor after redundancy allocation. To determine the original torque requirements of each motor before the redundancy function is activated, the subscript... This indicates the four motors: front left (FL), front right (FR), rear left (RL), and rear right (RR). The total torque adjustment is the sum of the absolute values of the torque adjustments for each motor. To ensure Introducing maximum torque adjustment range The torque adjustment cost subfunction J1 is defined as follows: ; The smaller the J1 value, the smaller the torque adjustment, the faster the vehicle can reach a new dynamic balance, and the higher the driving safety.
[0039] System efficiency cost sub-function J2 calculation: After drive redundancy control is activated, the overall vehicle system efficiency still needs to be considered, with a focus on optimizing the efficiency of the remaining normal motors during torque distribution. Motor efficiency is calculated using piecewise linear fitting, obtained by looking up the efficiency MAP table (i.e., the two-dimensional correspondence between motor speed, torque, and efficiency) using the motor speed and the target torque of each normal motor. For example, efficiency ; efficiency ; efficiency ; efficiency The lower the efficiency, the higher the cost. Sum the efficiencies of all normal motors and use the highest efficiency as the threshold. After normalization, we get J2: / ; in, For the first The efficiency value of a normal motor at its target torque. The smaller the J2 value, the higher the overall system efficiency and the lower the energy consumption.
[0040] Motor reserve capacity cost subfunction J3 calculation: When allocating torque, it's crucial to avoid overutilizing the capacity of any single motor to prevent wear on individual wheels or damage to motor components due to prolonged full-load operation. Simultaneously, it's essential to avoid insufficient motor capacity leading to delayed response under extreme speed conditions. Therefore, the concept of reserve capacity is introduced: the lower the remaining torque of the motor, the higher the cost. The reserve cost for each normal motor is defined as follows: ,in, For the first Torque capability limit of each motor For the first The target torque of each motor. Summing the reserve costs of all normal motors, we obtain J3: ; The smaller the J3 value, the more remaining capacity each motor has (i.e., the more sufficient the reserve), which is more conducive to coping with sudden working conditions and protecting the motor.
[0041] In summary, taking the complete failure of the left front motor as an example, the free variable is the target torque of the right front motor. According to the lateral and longitudinal dynamic constraint equations, the following relationships exist: ; ; ; Substituting the torque adjustment values for each motor, we can expand to: + + ; in, , , and are the original required torques (known constants) of each motor. This is the maximum torque adjustment amount (known calibration parameters). Because... To determine the value, therefore ignore The impact on optimization is considered only for the first two factors. Substituting, we get: + ; Therefore, J1 is only related to the free variables. Related to, let x = Then the above formula can be transformed into: J1= =|xa| + |xb|; The function curve is as follows Figure 2 , where a and b are known constants (determined by the original torque demand and longitudinal and yaw demands), and a > b. The minimum value of this function is |ba|, and it is piecewise continuous.
[0042] For the system efficiency cost subfunction J2, the motor efficiency is obtained by the efficiency MAP obtained by piecewise linear fitting of speed and torque. It is a linear function between efficiency segment points, so J2 is also a piecewise linear function of x.
[0043] For the motor reserve capacity cost subfunction J3, taking the failure of the left front motor as an example: ; in For the first The torque capacity limit of each motor (a known constant). For the first The target torque of each motor. Due to Since it is a fixed value, its corresponding term is a constant and can be ignored. Utilizing... Substituting, we get: ; It is evident that J3 is (i.e., a linear monotonic function of x).
[0044] In summary, a multi-objective cost function is constructed. : ; in, , , Let be the weighting coefficient, satisfying All of these values are greater than 0. Since J1 is an absolute value sum function (piecewise linear), J2 is a piecewise linear function, and J3 is a linear function, J(x) is a piecewise linear function. Its optimal solution must appear at the endpoints of the feasible region, the absolute value inflection point, or the efficiency piecewise point, and there must be an optimal solution.
[0045] Furthermore, multi-objective cost function Weighting coefficients in , , The settings are dynamically adjusted based on the vehicle's status. When the system detects a motor fault for the first time, to prioritize ensuring the vehicle can quickly regain stability and avoid instability due to slow torque adjustment, the controller adjusts the weighting coefficients of the torque adjustment cost sub-function. Set the weights to 1, and adjust the weights of the system efficiency cost subfunction and the motor reserve capacity cost subfunction. and All are set to 0. After the motors are controlled to drive the output according to the target torque and the vehicle enters a stable state (for example, the actual output torque of each motor has basically stabilized near the target torque value and the yaw rate deviation of the vehicle is less than the preset threshold), the controller readjusts the three weight coefficients according to the current road condition type (such as city, highway, mountain) and driving mode (such as economy, comfort, sport), as shown in Table 1 below.
[0046]
[0047] Table 1 In some examples, it also includes: If the motor fault information indicates that both motors have completely failed, then the sum of the target torques of the two motors on the non-failed side is set as the longitudinal required torque, and the difference between the target torques of the two motors on the non-failed side is set as the yaw differential torque. If the motor fault information indicates that the capacity of the two motors on the same side has been degraded, then the difference in target torque between the two motors on the degraded side is set as the yaw differential torque, the sum of target torque of the two motors on the degraded side is set as the minimum value between the total capacity limit of the two motors on the degraded side and the sum of the longitudinal demand torque and the yaw differential torque, the sum of target torque of the two motors on the non-degraded side is set as the longitudinal demand torque minus the sum of target torque of the two motors on the degraded side, and the difference in target torque of the two motors on the non-degraded side is set as the yaw differential torque minus the difference in target torque of the two motors on the degraded side. If the motor fault information indicates that the coaxial dual motors have degraded capability, then the sum of the target torques of the two motors on the degraded shaft is set to the minimum of the total capability limit of the two motors on the degraded shaft and the longitudinal required torque. The difference between the target torques of the two motors on the degraded shaft is set to the first preset ratio of the yaw differential torque. The sum of the target torques of the two motors on the non-degraded shaft is set to the longitudinal required torque minus the sum of the target torques of the two motors on the degraded shaft. The difference between the target torques of the two motors on the non-degraded shaft is set to the yaw differential torque minus the difference between the target torques of the two motors on the degraded shaft. If the motor fault information indicates that the dual motors on the cross-axis have degraded capabilities, then the target torques of the two motors on the degraded side are set to their respective degraded capability limits. The sum of the target torques of the two motors on the non-degraded side is set to the longitudinal demand torque minus the sum of the target torques of the two motors on the degraded side. The difference between the target torques of the two motors on the non-degraded side is set to the yaw differential torque minus the difference between the target torques of the two motors on the degraded side.
[0048] For example, when motor fault information indicates a dual-motor fault, the controller first identifies the fault type and adopts a preset torque distribution rule according to different situations, without the need for cost function optimization.
[0049] Dual motor failure on the same side: Taking the complete failure of both motors on the left side as an example. In this case, the torque capability on the left side is 0, and it cannot provide any longitudinal or yaw differential torque. The controller sets the target torque of both motors on the failed side (left side) to 0, and simultaneously performs speed limiting (e.g., limiting speed to 10 km / h). The sum of the target torques of the two motors on the unfailed side (right side) is set to the longitudinal torque requirement. The difference in target torque is set as the yaw differential torque. That is, the two motors on the right side must simultaneously meet the requirements for longitudinal driving force and steering differential.
[0050] Dual-motor capacity degradation on the same side: Taking the capacity degradation of the two motors on the left side as an example, let's assume the maximum capacity on the left side after degradation is... (That is, the total capacity limit of the two motors). The controller first obtains this total capacity limit. According to the lateral and longitudinal dynamic constraint equations, the total required torque on the left side should theoretically be... This value can be decomposed into the total longitudinal torque required on the left. And the total lateral differential torque required on the left ,Right now The allocation rules are as follows: when the actual torque capacity on the left side... Torque not meeting theoretical requirements At the same time, prioritize reducing the longitudinal torque demand. If it is still insufficient, then further reduce the lateral differential torque. Meanwhile, the maximum yaw differential torque limit is 2* ,in To compensate for torque, a certain overshoot capability is provided to cope with unexpected operating conditions. That is, provided the yaw differential torque requirement is met, the extra capability is used for driving; if the capability is insufficient, power degradation occurs. Based on the above rules, the controller sets the difference in target torque between the two motors on the degraded side as the yaw differential torque. (i.e., prioritizing yaw differential), the sum of the target torques of the two motors on the degraded side is set as the total capacity limit. Compared with theoretical torque requirements The minimum value is used (i.e., the capacity value is used when the capacity is insufficient, and the theoretical value is used when the capacity is excessive). Then, the sum of the target torques of the two motors on the non-degraded side (right side) is obtained by subtracting the sum of the torques on the degraded side from the longitudinal demand torque, and the difference in the target torques of the two motors on the non-degraded side is obtained by subtracting the difference in the torques on the degraded side from the yaw differential torque. In addition, to avoid vehicle instability under extreme operating conditions, the vehicle speed is limited (e.g., a speed limit of 60 km / h).
[0051] Complete failure of both coaxial motors: Taking the complete failure of both motors on the front axle as an example. In this situation, the front axle has no driving force, and the vehicle is treated as a rear-wheel drive vehicle. The controller sets the target torque of the two motors on the failed axle (front axle) to zero, and all longitudinal torque requirements and yaw differential torque are borne entirely by the unaffected axle (rear axle). That is, the sum of the target torques of the two motors on the rear axle is set to the longitudinal torque requirement. The difference in target torque is set as the yaw differential torque. At the same time, speed limits will be implemented (e.g., a speed limit of 80 km / h).
[0052] Coaxial Dual Motor Capacity Degradation: Taking the capacity degradation of the two motors on the front axle as an example, assume the front axle (degraded axle) retains some driving capacity, while the rear axle (undegraded axle) has normal capacity. The controller obtains the total capacity limit of the front axle. When allocating longitudinal torque demand, since the proportion of longitudinal torque demand is greater than the yaw differential torque, priority is given to having the rear axle bear most of the longitudinal torque demand, with the front axle only bearing a portion of the longitudinal demand when it has the capacity. Specifically, the sum of the target torques of the two motors on the front axle is set to the minimum of its total capacity limit and the longitudinal torque demand (i.e., the maximum longitudinal torque that the front axle can provide). Simultaneously, when allocating yaw differential torque, based on the reserve capacity of the rear axle, priority is given to having the rear axle provide most of the yaw differential torque (similar to rear-wheel steering). The allocation coefficient is related to parameters such as vehicle speed and throttle conditions to avoid oversteer. Therefore, the difference in target torques between the two motors on the front axle is set to a first preset proportion of the yaw differential torque (e.g., 0.3), meaning the front axle bears a smaller proportion of the yaw differential, and the rear axle bears a larger proportion (1 minus this proportion). Then, the sum of the target torques of the two motors on the rear axle (the non-degraded axle) equals the longitudinal demand torque minus the sum of the target torques on the front axle, and the difference in target torques between the two rear axle motors equals the yaw differential torque minus the difference in target torques on the front axle. When the front axle motor capacity exceeds its limit after the yaw differential torque is superimposed, the longitudinal demand torque is reduced first (i.e., the longitudinal portion of the front axle is reduced) to meet the yaw differential torque demand and ensure vehicle driving stability. In addition, when the system detects that the vehicle has an oversteer tendency, some of the yaw differential torque is promptly distributed to the front axle to suppress oversteer.
[0053] Cross-axle dual motor failure: For example, both the left front and right rear motors fail completely (cross-distributed). In this case, there is still one normal motor on each side (right front and left rear). The controller distributes the target torque of the remaining two motors evenly, setting the target torque of each normal motor to half of the longitudinal torque requirement, while ensuring that the difference in target torque between the two motors meets the yaw differential torque requirement. Specifically, the sum of the target torques of the two undisturbed motors is set as the longitudinal torque requirement, and the difference in target torques is set as the yaw differential torque. Speed limiting is also implemented (e.g., a speed limit of 80 km / h).
[0054] Cross-axle dual-motor capacity degradation: Taking the capacity degradation of the left front and right rear motors as an example, the controller determines the speed limit target based on the proportion of capacity retained on the degraded side (e.g., the speed limit can be increased to 120 km / h when half the capacity is retained). To simplify control, the torque of the four motors is evenly distributed, meaning the initial target torque for each motor is set to the longitudinal demand torque. One-quarter. During the allocation process, if the target torque of any motor exceeds its torque capacity limit, the longitudinal torque demand will be reduced first. The reduced torque is compensated equally by the two motors on the opposite cross axle (i.e., the left rear and right front), with the principle of compensation being to prevent unintended yaw. When the differential torque distribution causes a motor's torque to exceed its capacity, the excess is preferentially added to the motor on the same side (e.g., if the left front exceeds its limit, it is added to the left rear). If the added torque also exceeds the capacity limit of the motor on the same side, then the longitudinal torque requirement is reduced preferentially. At the same time, to avoid unintended yaw caused by reducing the longitudinal torque requirement, the opposite motor is subjected to the same torque reduction treatment (i.e., the longitudinal torque is reduced symmetrically from left to right) to ensure the overall vehicle driving stability.
[0055] In some examples, when a three-motor failure occurs, whether the motor is downgraded or ineffective, the vehicle speed is limited to 10 km / h to ensure driving safety and allow the driver to move the vehicle.
[0056] In some examples, it also includes: Based on the external characteristic capability limits of each motor and the driving capability limits of the distributed drive system, the torque capability limits of each motor are determined. Based on the vehicle's longitudinal acceleration, lateral acceleration, and wheel loads, the road adhesion limit for each wheel is determined.
[0057] For example, before implementing all the above control methods, it is necessary to predetermine the torque capability of each motor and the road adhesion capability limit of each wheel. The torque capability limit is calculated as follows: obtain the external characteristic capability limit of each motor (i.e., the peak torque curve of the motor at different speeds), and at the same time obtain the drive capability limit of the distributed drive system (including the current maximum allowable discharge power of the battery, the temperature limit of the motor controller, etc.), and take the smaller value of the two as the real-time torque capability limit of the motor.
[0058] The road surface adhesion limit is calculated by obtaining the longitudinal acceleration through the vehicle's inertial sensor. and lateral acceleration Calculate the vehicle adhesion coefficient ,in The adhesion coefficient, It is the acceleration due to gravity. The calibrated adhesion coefficient tolerance value is used; then, based on the vertical load on each wheel (which can be estimated using suspension height sensors or a dynamic model), the road adhesion limit value for each wheel is calculated. ,in For the load on each wheel. These capability limits are used in the torque distribution process to limit the target torque of the motor, correct the total required torque on the left and right sides, and define the feasible region of free variables.
[0059] Furthermore, this application also proposes a distributed four-motor drive redundancy control system for implementing any of the above-mentioned distributed four-motor drive redundancy control methods, specifically as follows: Figure 3 The diagram shown is a functional block diagram of a distributed four-motor drive redundancy control system proposed in this application, including: The data acquisition unit 21 is used to determine the longitudinal torque demand and yaw differential torque of the vehicle based on the driver's acceleration and steering operations. The function construction unit 22 is used to construct a multi-objective cost function based on multiple of the original required torque, motor speed, and torque capacity limit of each motor if the motor fault information of the vehicle represents a single motor abnormality. The multi-objective cost function includes multiple of the torque adjustment cost sub-function, system efficiency cost sub-function, and motor reserve capacity cost sub-function. The torque control unit 23 is used to determine the target torque of each normal motor based on the multi-objective cost function, longitudinal demand torque and yaw differential torque, and control the corresponding normal motor to perform drive output according to the target torque.
[0060] It should be noted that the above embodiments are merely best examples and are not intended to limit the implementation of this application.
[0061] Furthermore, such as Figure 4 As shown, this application embodiment also provides an electronic device 300, including a processor 310, a memory 320, and a computer program 321 stored in the memory 320 and executable on the processor. When the processor 310 executes the computer program 321, it implements the steps of any of the above-described distributed four-motor drive redundancy control methods.
[0062] Since the electronic device described in this embodiment is the device used to implement a distributed four-motor drive redundancy control method in the embodiments of this application, those skilled in the art can understand the specific implementation method and various variations of the electronic device in this embodiment based on the method described in the embodiments of this application. Therefore, how the electronic device implements the method in the embodiments of this application will not be described in detail here. Any device used by those skilled in the art to implement the method in the embodiments of this application falls within the scope of protection of this application.
[0063] In practical implementation, when the computer program 321 is executed by the processor, it can achieve the following: Figure 1 Any of the corresponding implementation methods in the embodiments.
[0064] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0065] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-readable program code.
[0066] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0067] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0068] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0069] This application also provides a computer program product, which includes computer software instructions that, when executed on a processing device, cause the processing device to execute a distributed four-motor drive redundancy control method.
[0070] A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).
[0071] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0072] In the several embodiments provided in this application, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or units, and may be electrical, mechanical, or other forms.
[0073] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0074] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.
[0075] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0076] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
[0077] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.
[0078] Obviously, those skilled in the art can make various modifications and variations to this specification without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, this specification is also intended to include such modifications and variations.
Claims
1. A distributed four-motor drive redundancy control method, characterized in that, Applied to a distributed drive system, the distributed drive system comprising four motors, the method includes: Based on the driver's acceleration and steering actions, the vehicle's longitudinal torque demand and yaw differential torque are determined. If the motor fault information of the vehicle indicates a single motor abnormality, then a multi-objective cost function is constructed based on multiple of the original required torque, motor speed, and torque capacity limit of each motor. The multi-objective cost function includes multiple of the torque adjustment cost sub-function, system efficiency cost sub-function, and motor reserve capacity cost sub-function. The target torque of each normal motor is determined based on the multi-objective cost function, the longitudinal demand torque, and the yaw differential torque, and the corresponding normal motor is controlled to perform drive output according to the target torque.
2. The method according to claim 1, characterized in that, The determination of the target torque for each normal motor based on the multi-objective cost function, the longitudinal demand torque, and the yaw differential torque includes: The sum of the target torques of the two normal motors on the opposite side of the abnormal motor is determined as the average of the difference between the longitudinal required torque and the yaw differential torque; The target torque of one of the normal motors on the opposite side of the abnormal motor is determined based on the multi-objective cost function; Based on the average value of the difference between the longitudinal demand torque and the yaw differential torque, and the target torque of one of the normal motors on the opposite side of the abnormal motor, the target torque of the other normal motor on the opposite side of the abnormal motor is determined.
3. The method according to claim 2, characterized in that, Determining the target torque of one of the normal motors on the opposite side of the abnormal motor based on the multi-objective cost function includes: Determine the feasible region of the free variables in the multi-objective cost function; Based on the absolute value inflection point in the torque adjustment cost sub-function and the efficiency segmentation point in the system efficiency cost sub-function, the feasible region is divided into several sub-intervals; Obtain the minimum cost value of the multi-objective cost function in each sub-interval; Compare the minimum value corresponding to all sub-intervals, and determine the sub-interval corresponding to the minimum value with the smallest value as the optimal interval; Within the optimal range, the optimal value of the free variable is selected as the target torque of one of the normal motors based on the minimum torque adjustment cost.
4. The method according to claim 3, characterized in that, Obtaining the minimum cost value of the multi-objective cost function in each sub-interval includes: If the multi-objective cost function is a constant within the sub-interval, then the constant is taken as the minimum cost value; If the multi-objective cost function within the sub-interval is a monotonic function, then the multi-objective cost function values at the two endpoints of the sub-interval are obtained, and the minimum value among the multi-objective cost function values at the two endpoints is taken as the minimum cost value.
5. The method according to claim 1, characterized in that, The determination of the target torque for each normal motor based on the multi-objective cost function, the longitudinal demand torque, and the yaw differential torque also includes: If a single motor malfunctions as a complete failure of that single motor, the target torque of the normal motor on the same side as the malfunctioning motor is determined as the average of the sum of the longitudinal required torque and the yaw differential torque. If a single motor malfunction is a degradation of the single motor's capacity and the original required torque of the malfunctioning motor is greater than the degradation capacity limit of the malfunctioning motor, then the target torque of the malfunctioning motor is determined as the degradation capacity limit. Based on the average value of the sum of the longitudinal demand torque and the yaw differential torque, and the degradation capability limit, the target torque of the normal motor on the same side as the abnormal motor is determined.
6. The method according to claim 5, characterized in that, After determining the target torque of the normal motor on the same side as the abnormal motor as the average of the sum of the longitudinal required torque and the yaw differential torque, the method further includes: If a single motor malfunction is a complete failure of that single motor, and the target torque of the normal motor on the same side as the malfunctioning motor is greater than the torque capability limit of the normal motor on the same side as the malfunctioning motor or the road surface adhesion capability limit of the wheel where the normal motor on the same side as the malfunctioning motor is located, then the target torque of the normal motor on the same side as the malfunctioning motor is corrected to the minimum value between the torque capability limit and the road surface adhesion capability limit.
7. The method according to claim 1, characterized in that, Also includes: Based on the external characteristic capability limits of each motor and the driving capability limits of the distributed drive system, the torque capability limits of each motor are determined. Based on the vehicle's longitudinal acceleration, lateral acceleration, and wheel loads, the road adhesion limit for each wheel is determined.
8. The method according to claim 1, characterized in that, The multi-objective cost function is obtained by weighted summation of the torque adjustment cost sub-function, the system efficiency cost sub-function, and the motor reserve capacity cost sub-function, wherein the weight coefficients of the torque adjustment cost sub-function, the system efficiency cost sub-function, and the motor reserve capacity cost sub-function are obtained in the following manner: If a motor failure occurs for the first time, the weight coefficient of the torque adjustment cost subfunction is set to 1, and the weight coefficients of the system efficiency cost subfunction and the motor reserve capacity cost subfunction are set to 0. After the normal motor is controlled to perform drive output according to the target torque, the weight coefficients are adjusted according to the road condition type and driving mode.
9. The method according to claim 1, characterized in that, Also includes: If the motor fault information indicates that both motors have completely failed, then the sum of the target torques of the two motors on the non-failed side is set as the longitudinal required torque, and the difference between the target torques of the two motors on the non-failed side is set as the yaw differential torque. If the motor fault information indicates a degradation in the capability of the two motors on the same side, then the difference in target torque between the two motors on the degraded side is set as the yaw differential torque, the sum of target torques of the two motors on the degraded side is set as the minimum value among the total capability limit of the two motors on the degraded side and the average of the sum of the longitudinal demand torque and the yaw differential torque, the sum of target torques of the two motors on the non-degraded side is set as the longitudinal demand torque minus the sum of target torques of the two motors on the degraded side, and the difference in target torques of the two motors on the non-degraded side is set as the yaw differential torque minus the difference in target torques of the two motors on the degraded side. If the motor fault information indicates a degradation in the capability of the coaxial dual motors, then the sum of the target torques of the two motors on the degraded shaft is set to the minimum value between the total capability limit of the two motors on the degraded shaft and the longitudinal required torque; the difference between the target torques of the two motors on the degraded shaft is set to the first preset ratio value of the yaw differential torque; the sum of the target torques of the two motors on the non-degraded shaft is set to the longitudinal required torque minus the sum of the target torques of the two motors on the degraded shaft; and the difference between the target torques of the two motors on the non-degraded shaft is set to the yaw differential torque minus the difference between the target torques of the two motors on the degraded shaft. If the motor fault information indicates a degradation in the capability of the cross-axis dual motors, then the target torques of the two motors on the degradation side are set to their respective degradation capability limits, the sum of the target torques of the two motors on the non-degraded side is set to the longitudinal required torque minus the sum of the target torques of the two motors on the degradation side, and the difference in the target torques of the two motors on the non-degraded side is set to the yaw differential torque minus the difference in the target torques of the two motors on the degradation side.
10. A distributed four-motor drive redundancy control system, characterized in that, include: The data acquisition unit is used to determine the vehicle's longitudinal torque demand and yaw differential torque based on the driver's acceleration and steering operations. The function construction unit is used to construct a multi-objective cost function based on multiple of the original required torque, motor speed, and torque capacity limit of each motor if the motor fault information of the vehicle indicates a single motor abnormality. The multi-objective cost function includes multiple of the torque adjustment cost sub-function, system efficiency cost sub-function, and motor reserve capacity cost sub-function. The torque control unit is used to determine the target torque of each normal motor based on the multi-objective cost function, the longitudinal demand torque, and the yaw differential torque, and to control the corresponding normal motor to perform drive output according to the target torque.