Torque distribution method, device and equipment for double electric drive axles and medium

Abstract

The invention relates to the field of power control methods of new energy automobiles, in particular to a torque distribution method, device, equipment and medium for double electric drive axles, and the method comprises the following steps: step 1, before running of an automobile, on the basis of efficiency MAP maps of a front electric drive axle and a rear electric drive axle, taking the comprehensive efficiency of a system as an optimization target, and optimizing the efficiency MAP maps of the front electric drive axle and the rear electric drive axle; pre-calculating and generating an optimal torque distribution mapping table covering all working conditions; 2, in the running process of the vehicle, quick torque distribution is conducted on the double electric drive axles by inquiring the optimal torque distribution mapping table pre-generated in the step 1; and step 3, monitoring the instability condition in the vehicle operation process in real time, and when the instability condition is monitored, covering the optimal distribution strategy of the efficiency. Complex global optimization calculation is completed in an off-line mode, and rapid torque distribution is achieved through table look-up interpolation in the on-line control stage.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power control methods for new energy vehicles, in particular to a torque distribution method and device for dual electric drive axle, equipment and medium. BACKGROUND

[0002] With the development of new energy vehicle technology, electric heavy trucks are increasingly widely used in the field of logistics transportation. To balance power and energy efficiency, some models use a hybrid drive architecture with dual electric drive axles. The core challenge of this architecture is how to reasonably distribute torque between the two electric drive axles under different working conditions to achieve the best balance of vehicle power, economy and stability.

[0003] Currently, existing torque distribution methods for dual electric drive axles mainly include the following technical routes: The fixed proportion distribution method uses a fixed torque distribution ratio (such as 50:50) to drive control the two motors. This method is simple to implement but cannot be dynamically adjusted according to the actual driving conditions of the vehicle, resulting in the vehicle's performance not being optimal under different conditions. The single parameter rule-based distribution method distributes torque based on a single sensor signal (such as vehicle speed or throttle pedal opening). Although it can achieve a certain degree of dynamic adjustment, it cannot fully and accurately reflect the actual operating state of the vehicle due to limited considerations. The real-time optimization calculation method determines the optimal distribution scheme by calculating the required power of each motor under multiple preset distribution coefficients in real time. Although this method has good optimization results, it has a large amount of calculation and poor real-time performance, requiring high computing power of the vehicle controller. In addition, when the dual electric drive axle is in different gears, the fixed proportion distribution strategy will result in different axle end torques due to different gear ratios, increasing the risk of drive wheel slip. Unreasonable torque distribution during gear shifting also leads to long gear shifting time, power interruption and other problems, affecting the power and smoothness of the vehicle.

[0004] Through in-depth analysis of existing technologies, the following problems and defects are found: (1) Conflict between calculation complexity and real-time performance The existing real-time optimization method needs to calculate the total required power under multiple preset distribution coefficients in real time during vehicle operation, and determine the target distribution coefficient by comparison. This method has a large amount of calculation, and the computing resources of the vehicle controller (VCU) are limited, making it difficult to meet the requirements of real-time control, resulting in delayed torque response and affecting the dynamic performance of the vehicle.

[0005] (2) Insufficient global optimization capability The fixed proportion allocation and the allocation method based on simple rules cannot realize efficiency optimization in the whole working condition range. The real-time optimization method solves the efficiency optimization problem to some extent, but due to the limitation of calculation amount, it can only select from limited preset allocation coefficients, and it is difficult to find the real global optimal solution.

[0006] (3) Poor adaptability to special working conditions In the shifting process, slipping working condition and different gears, the existing torque distribution method often performs poorly. For example, in the shifting process, the traditional method needs to reduce the torque or even reduce the torque to zero before shifting, which leads to long shifting time and power interruption, affecting the power and smoothness of the vehicle. When the double electric drive axle is in different gears, the fixed proportion allocation will cause the torque at the axle end to be inconsistent, increasing the risk of slipping.

[0007] (4) Unbalanced load of electric machines The existing allocation strategy is easy to cause a single electric machine to run for a long time under high load, while the other electric machine has insufficient utilization. This unbalanced load will accelerate the aging and wear of the high-load electric machine, shorten the service life of the electric machine, and reduce the overall reliability of the system. SUMMARY

[0008] The present application provides a torque distribution method, device, equipment and medium for a double electric drive axle, to solve the problems of large calculation amount, poor real-time performance, poor performance of the existing allocation method under shifting and slipping working conditions.

[0009] According to one aspect of the present application, a torque distribution method for a double electric drive axle is provided, comprising the following steps: Step 1, before the vehicle runs, based on the efficiency MAP of the front electric drive axle and the rear electric drive axle, taking the system comprehensive efficiency as the optimization target, precalculating and generating an optimal torque distribution mapping table covering the whole working condition; Step 2, during the vehicle running, querying the optimal torque distribution mapping table generated in step 1 to quickly distribute the torque of the double electric drive axle; Step 3, real-time monitoring of the instability condition during the vehicle running, when the instability condition is monitored, the efficiency optimal distribution strategy is covered.

[0010] The beneficial effects of the present application are as follows: Based on the precalculation and query architecture, the torque of the double electric drive axle is distributed, the complex global optimization calculation is completed offline, and the torque is quickly distributed through table lookup interpolation in the online control stage.

[0011] Further, in step 1, the calculation process of the optimal torque distribution mapping table comprises the following sub-steps: Sub-step 1.1, obtaining the accurate efficiency MAP data of the front electric drive axle and the rear electric drive axle assembly; Sub-step 1.2, determine the total demand torque range and the motor speed range, define a two-dimensional working condition grid; Sub-step 1.3, for each point in the two-dimensional working condition grid, calculate the system comprehensive efficiency under all possible distribution ratios, find the optimal distribution ratio with the highest efficiency; Sub-step 1.4, generate a two-dimensional lookup table of the optimal distribution ratio in the full working condition range and store it.

[0012] The beneficial effect is that the mapping table is calculated offline according to the corresponding parameters, greatly reducing the amount of processor operation during vehicle operation.

[0013] Further, in the sub-step 1.3, the formula for calculating the system comprehensive efficiency is: η_system = P_out_total / P_in_total =(T_total×n / 9550) / [T_front×n / (9550×η_front)+T_rear×n / (9550×η_rear)]; Where P_out_total is the output power (kW), P_in_total is the input power (kW), n is the motor speed (rpm), T_total is the total demand torque (N.m), T_front is the front axle distribution torque (N.m), T_rear is the rear axle distribution torque (N.m), ratio is the torque distribution ratio, η_front is the front axle efficiency, T_front = ratio × T_total, η_rear is the rear axle efficiency, T_rear = (1-ratio) × T_total.

[0014] Further, in the step 2, the process of querying the optimal torque distribution mapping table includes the following sub-steps: Sub-step 2.1, real-time acquisition of the total demand torque signal and the current vehicle speed signal of the running vehicle; Sub-step 2.2, calculate the motor speed according to the vehicle speed, tire rolling radius and main reduction ratio; Sub-step 2.3, query the optimal torque distribution mapping table with the total demand torque and the motor speed as input, and calculate the real-time optimal distribution ratio of the two electric drive axles through the interpolation algorithm; Sub-step 2.4, calculate the torque command of the front electric drive axle and the rear electric drive axle according to the optimal distribution ratio obtained in sub-step 2.3; Sub-step 2.5, distribute the torque command obtained in sub-step 2.4 to the front axle motor controller and the rear axle motor controller.

[0015] The beneficial effects are: during the query, calculations are performed based on the actual situation of the vehicle, and then the optimal allocation ratio is calculated by looking up a table, which improves the accuracy of control and avoids vehicle instability.

[0016] Furthermore, in sub-step 2.3, the formula for calculating the precise optimal allocation ratio using the interpolation algorithm is as follows: ; Where α and β are normalized distance coefficients.

[0017] Furthermore, in sub-step 2.4, the formula for calculating the torque command is: T_front = ratio × T_total; T_rear = (1-ratio) × T_total.

[0018] Furthermore, in step 3, the instability is monitored in real time by the wheel slip ratio. When the wheel slip ratio exceeds the threshold, a safety mode is triggered. In the safety mode, a torque distribution strategy based on adhesion conditions is adopted to cover the optimal distribution efficiency.

[0019] The beneficial effect is that monitoring instability by implementing wheel slip rate can improve the accuracy of monitoring results.

[0020] According to another aspect of the present invention, a torque distribution device for a dual electric drive axle is provided, comprising a vehicle controller module, a front axle motor controller module, a rear axle motor controller module, and a sensor module. The sensor module is used to detect the total required torque signal and the current vehicle speed signal. The vehicle controller module is used to execute offline pre-calculation and online real-time distribution algorithms and generate torque commands. The front axle motor controller module and the rear axle motor controller module receive the torque commands sent by the vehicle controller module and control the torque output of the corresponding motors.

[0021] According to another aspect of the present invention, a torque distribution device for a dual electric drive bridge is provided, comprising at least one processor and a memory communicatively connected to the at least one processor, the memory storing a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the torque distribution method for the dual electric drive bridge described above.

[0022] According to another aspect of the present invention, a medium is provided storing computer instructions for causing a processor to execute the torque distribution method of the dual electric drive bridge described above. Attached Figure Description

[0023] Figure 1This is a schematic block diagram of a torque distribution method for a dual electric drive bridge according to Embodiment 1 of the present invention. Detailed Implementation

[0024] The following detailed description provides further details on specific implementation methods.

[0025] Example 1 A torque distribution method for dual electric drive bridges, such as Figure 1 As shown, it includes the following steps: Step 1: Before vehicle operation, based on the efficiency MAP diagrams of the front and rear electric drive axles, and with the overall system efficiency as the optimization objective, pre-calculate and generate an optimal torque distribution mapping table covering all operating conditions. "Before vehicle operation" refers to either before the vehicle leaves the factory or during an onboard software update.

[0026] For each (T_total, n) operating point, the motor capacity is calibrated using a test bench. The calculation process of the optimal torque distribution mapping table, which iterates through all distribution ratios, includes the following sub-steps: Sub-step 1.1: Obtain accurate efficiency MAP data for the front and rear electric drive axles. The efficiency MAP data is obtained from the suppliers of the front and rear axle motors and controllers. This data represents the efficiency value of the motor at different speeds and torques.

[0027] Sub-step 1.2: Determine the total required torque range and motor speed range, define and form a two-dimensional operating condition mesh, and define the range and accuracy for the entire operating condition as follows: The total required torque range is 0-500 Nm, in increments of 10 Nm; The motor speed range is 0-5000rpm, with a step size of 100rpm. The allocation ratio ranges from 0% to 100%, with a step size of 1%.

[0028] Sub-step 1.3: For each point in the two-dimensional load cell grid, calculate the overall system efficiency under all possible allocation ratios, and find the optimal allocation ratio with the highest efficiency. The formula for calculating the overall system efficiency is: η_system = P_out_total / P_in_total =(T_total×n / 9550) / [T_front×n / (9550×η_front)+T_rear×n / (9550×η_rear)]; Where η_system is the overall system efficiency, P_out_total is the output power (kW), P_in_total is the input power (kW), n is the motor speed (rpm), T_total is the total required torque (Nm), T_front is the torque distributed to the front axle (Nm), T_rear is the torque distributed to the rear axle (Nm), ratio is the torque distribution ratio, η_front is the front axle efficiency (T_front = ratio × T_total), η_rear is the rear axle efficiency (T_rear = (1 - ratio) × T_total), and T_total × n / 9550 is the power.

[0029] Sub-step 1.4 generates a two-dimensional lookup table of the optimal allocation ratio across the entire operating range and stores it. This two-dimensional lookup table is the optimal torque allocation mapping table. Specifically, it finds the optimal allocation ratio ratio_optimal that maximizes η_system, fills it into the two-dimensional lookup table, and stores it in the vehicle controller (VCU) memory.

[0030] Step 2: During vehicle operation, the optimal torque distribution map pre-generated in Step 1 is used to quickly distribute torque to the dual electric drive axles. The process of querying the optimal torque distribution map includes the following sub-steps: Sub-step 2.1: Real-time acquisition of the total demand torque signal and current vehicle speed signal of the operating vehicle. The vehicle controller (VCU) acquires the total demand torque signal (which comes from the accelerator pedal or the autonomous driving system) through the CAN bus and the current vehicle speed signal through the vehicle speed sensor. The acquired signals are filtered using existing algorithms to eliminate noise interference.

[0031] Sub-step 2.2 calculates the motor speed based on the current vehicle speed, tire rolling radius, and final drive ratio. The rolling radius is determined by the selected tire specifications and has a corresponding relationship. There are some industry default values, such as 0.525m for a 12R22.5 tire. The calculation formula is: Motor speed N (rpm) is expressed as: ; Where V is the vehicle speed, in km / h. The main reduction ratio is given by r, where r is the tire rolling radius in meters (m), and 0.377 is a constant.

[0032] Sub-step 2.3: Using the total required torque and motor speed as input, query the optimal torque distribution mapping table to obtain the optimal distribution ratio between the front and rear axles. Then, calculate the real-time optimal distribution ratio between the two electric drive axles using an interpolation algorithm. The query uses (T_total, n) as input and finds the four nearest grid points in the optimal torque distribution mapping table. The precise optimal distribution ratio is calculated using a bilinear interpolation algorithm, with the following formula: ; Where α and β are normalized distance coefficients, and i and j have no special meaning.

[0033] Sub-step 2.4: Calculate the torque commands for the front and rear electric drive axles based on the optimal allocation ratio obtained in sub-step 2.3. The formula for calculating the torque commands is as follows: T_front = ratio × T_total; T_rear = (1-ratio) × T_total.

[0034] The calculated torque command is sent to the front axle motor controller and the rear axle motor controller via the CAN bus.

[0035] Sub-step 2.5: Distribute the torque command obtained in sub-step 2.4 to the front axle motor controller and the rear axle motor controller.

[0036] Step 3: Real-time monitoring of vehicle instability during operation. When instability is detected, the optimal coverage efficiency allocation strategy is executed. This strategy is performed by querying a pre-calculated MAP table. Instability is monitored in real-time by the wheel slip ratio. When the wheel slip ratio exceeds a threshold, a safety mode is triggered. In safety mode, a torque distribution strategy based on adhesion conditions is adopted for optimal coverage efficiency allocation. This threshold is not a single fixed value, but a comprehensive strategy considering multiple factors: it requires extensive data collection and calibration considering vehicle status (e.g., speed, slip ratio), road adhesion conditions, and tire characteristics to ensure adaptability for most operating conditions.

[0037] Road surface adhesion conditions include: 1. The higher the vehicle speed, the worse the stability, and the more stringent (i.e., the smaller) the threshold should be set. At high speeds, even a small slip ratio can cause danger, so the threshold should be lowered.

[0038] 2. The worse the road surface adhesion (such as ice or water), the stricter the threshold should be set. On low-adhesion roads, the allowable slip ratio range is very narrow, and the threshold needs to be lowered accordingly.

[0039] 3. Different tires have different grip limits, and the threshold needs to be adjusted accordingly. The threshold for high-performance tires may be set higher than that for economy tires.

[0040] Compared with existing technologies, this embodiment constructs a fast, effective, and safe torque distribution method for dual electric drive axles through an architecture of offline calculation, online lookup table interpolation, and a safety fault-tolerance mechanism. It pre-calculates the global optimal solution offline, requiring only lookup table interpolation online, significantly reducing computational complexity by over 90% and improving real-time performance. Global optimization based on a full-condition efficiency map significantly enhances optimization effects, improving overall system efficiency by 3-5% and improving economic efficiency. The lookup table interpolation method achieves a response time of less than 10ms, resulting in faster response speeds and meeting the real-time control requirements of high-performance vehicles. The integrated safety fault-tolerance mechanism prioritizes stability under special conditions, comprehensively improving vehicle safety and adaptability, with stronger adaptability to special conditions. Different vehicle models can be adapted to different needs simply by changing the pre-calculated mapping table, making the system highly flexible, scalable, and easy to upgrade and maintain.

[0041] Example 2 A torque distribution device for a dual-electric drive axle includes a vehicle controller module, a front axle motor controller module, a rear axle motor controller module, and a sensor module. The sensor module is used to detect the total required torque signal and the current vehicle speed signal. The sensor module includes a vehicle speed sensor, a motor speed sensor, and an accelerator pedal opening sensor. The vehicle controller module (VCU) is used to execute offline pre-calculation and online real-time distribution algorithms and generate torque commands. The front axle motor controller module and the rear axle motor controller module receive the torque commands sent by the vehicle controller module and control the torque output of the corresponding motors.

[0042] In the specific allocation process, the system is first initialized: the VCU is powered on, the optimal torque allocation mapping table is loaded into memory, and each sensor and actuator is initialized.

[0043] Normal torque distribution process: When the driver presses the accelerator pedal, the VCU calculates the total torque required based on the pedal opening and vehicle speed. VCU calculates the motor speed based on the current vehicle speed; Query the optimal allocation mapping table and obtain the optimal allocation ratio; Calculate and output the torque commands for the front and rear axles; The above process is repeated to achieve real-time torque distribution.

[0044] Special operating condition handling procedures: When special operating conditions such as gear shifting or slippage are detected, the corresponding torque distribution strategy for special operating conditions shall be executed first. After the special operating condition ends, the normal torque distribution mode is restored. This second embodiment, through the above specific implementation method, achieves high efficiency, fast response and good adaptability of torque distribution of dual electric drive bridges, effectively overcoming the defects of the prior art.

[0045] Example 3 A torque distribution device for a dual electric drive axle includes at least one processor and a memory communicatively connected to the at least one processor. The memory stores a computer program executable by the at least one processor, which is executed by the at least one processor to enable the at least one processor to perform the torque distribution method for a dual electric drive axle of Embodiment 1.

[0046] Example 4 A medium storing computer instructions for causing a processor to execute the torque distribution method of the dual electric drive bridge in Embodiment 1.

[0047] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method of torque distribution for a dual electric drive axle, characterized in that, The method comprises the following steps: Step 1, before the vehicle runs, based on the efficiency MAP of the front electric drive axle and the rear electric drive axle, the optimal torque distribution mapping table covering all working conditions is pre-calculated and generated with the system comprehensive efficiency as the optimization target; Step 2, during the running of the vehicle, the fast torque distribution of the double electric drive axle is realized by querying the optimal torque distribution mapping table generated in step 1; Step 3, the instability condition during the running of the vehicle is monitored in real time, and when the instability condition is monitored, the efficiency optimal distribution strategy is covered. 2.The torque distribution method of a dual-motor-drive axle according to claim 1, characterized in that: In the step 1, the calculation process of the optimal torque distribution mapping table comprises the following sub-steps: Sub-step 1.1, the accurate efficiency MAP data of the front electric drive axle and the rear electric drive axle assembly are obtained; Sub-step 1.2, the total demand torque range and the motor speed range are determined, and a two-dimensional working condition grid is defined; Sub-step 1.3, for each point in the two-dimensional working condition grid, the system comprehensive efficiency under all possible distribution ratios is calculated, and the optimal distribution ratio with the highest efficiency is found; Sub-step 1.4, the optimal distribution ratio in the whole working condition range is generated into a two-dimensional lookup table and stored.

3. The torque distribution method for a dual electric drive axle according to claim 2, characterized in that: In the sub-step 1.3, the calculation formula of the system comprehensive efficiency is: η_system = P_out_total / P_in_total =(T_total×n / 9550) / [T_front×n / (9550×η_front)+T_rear×n / (9550×η_rear)]; Wherein, P_out_total is the output power (kW), P_in_total is the input power (kW), n is the motor speed (rpm), T_total is the total demand torque (N.m), T_front is the front axle distribution torque (N.m), T_reart is the rear axle distribution torque (N.m), ratio is the torque distribution ratio, η_front is the front axle efficiency, T_front=ratio×T_total, η_rear is the rear axle efficiency, T_rear=(1-ratio)×T_total.

4. The torque distribution method for a dual electric drive axle according to claim 3, characterized in that: In the step 2, the process of querying the optimal torque distribution mapping table comprises the following sub-steps: Sub-step 2.1, the total demand torque signal and the current vehicle speed signal of the running vehicle are obtained in real time; Sub-step 2.2, the motor speed is calculated according to the vehicle speed, the tire rolling radius and the main reduction ratio; Sub-step 2.3, the optimal torque distribution mapping table is queried with the total demand torque and the motor speed as the input, and the real-time optimal distribution ratio of the two electric drive axles is calculated through the interpolation algorithm; Sub-step 2.4, the torque instructions of the front electric drive axle and the rear electric drive axle are calculated according to the optimal distribution ratio obtained in sub-step 2.3; Sub-step 2.5, the torque instructions obtained in sub-step 2.4 are distributed to the front axle motor controller and the rear axle motor controller.

5. The method of claim 4, wherein: In the sub-step 2.3, the formula for calculating the accurate optimal distribution ratio by the interpolation algorithm is: ； Wherein, α and β are normalized distance coefficients.

6. The torque distribution method for a dual electric drive axle according to claim 5, characterized in that: In the sub-step 2.4, the calculation formula of the torque instruction is: T_front=ratio×T_total; T_rear = (1-ratio) x T_total.

7. The method of claim 1, wherein: In step 3, the unstable condition is monitored in real time by monitoring the wheel slip ratio, and when the wheel slip ratio exceeds a threshold value, a safety mode is triggered, in which an adhesion condition-based torque distribution strategy is adopted to override the efficiency optimal distribution.

8. A torque distribution device of a dual electric drive axle, comprising a vehicle control module, a front axle motor controller module, a rear axle motor controller module, a sensor module, the sensor module is used to detect a total demand torque signal and a current vehicle speed signal, characterized in that: The vehicle control module is configured to perform offline pre-calculation and online real-time distribution algorithms according to the torque distribution method of any one of claims 1-7, and generate torque instructions; the front axle motor controller module and the rear axle motor controller module receive the torque instructions sent by the vehicle control module and control the torque output of the corresponding motor. 9.A torque distribution device of a dual electric drive axle, comprising at least one processor and a memory connected with the at least one processor, the memory storing a computer program executable by the at least one processor, characterized in that: The computer program is executed by the at least one processor to enable the at least one processor to perform the torque distribution method of the dual electric drive axle according to any one of claims 1-7.

10. A medium storing computer instructions, characterized by: The computer instructions are used to enable the processor to implement the torque distribution method of the dual electric drive axle according to any one of claims 1-7 when executed.

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