A layered coordination control method and system for an in-wheel motor drive system

Abstract

The application relates to the field of vehicle control and provides a layered coordination control method and system for a wheel hub motor driving system. The method comprises the following steps: obtaining a pedal signal and a vehicle running state, and identifying a total demand torque; through a torque coordination controller, a multi-target coordination distribution is performed on the total demand torque to obtain independent torque instructions of multiple wheel hub motors; through multiple motor controllers, the independent torque instructions are respectively executed to obtain actual output torques of the multiple wheel hub motors; according to the actual output torques, feedback information of the multiple wheel hub motors is subjected to fault diagnosis and reconstruction through the torque coordination controller to obtain an updated torque distribution strategy; and the multiple wheel hub motors are controlled based on the updated torque distribution strategy to complete layered coordination control of the wheel hub motor driving system. The application significantly improves the response speed, control stability and fault tolerance capability of a four-wheel wheel hub motor driving system.

Description

Technical Field

[0001] This invention belongs to the field of vehicle control technology, and in particular relates to a hierarchical coordinated control method and system for a hub motor drive system. Background Technology

[0002] Four-wheel hub motor drive technology eliminates traditional mechanical components such as drive shafts and differentials, and has significant advantages such as high transmission efficiency, high space utilization, and the ability to achieve independent and precise control of torque for each wheel, providing new possibilities for improving vehicle dynamic performance (such as handling stability, drive anti-skid, active safety, etc.).

[0003] The current common solution for hub motor drive control is that the VCU directly controls all MCUs, that is, the VCU calculates the torque command for each hub motor. This greatly increases the computational burden of the VCU, making it difficult to meet real-time requirements. Moreover, a VCU failure will cause the entire vehicle drive to fail. In addition, the existing technology does not distribute the total required torque evenly to the four motors, which fails to take advantage of the independent control of the hub motors and cannot achieve advanced dynamic control. At the same time, there is a lack of a controller that focuses on torque distribution and coordination between the VCU and multiple MCUs, resulting in scattered control logic, slow response, and poor coordination. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of the invention is to provide a hierarchical coordinated control method and system for a hub motor drive system.

[0005] This invention first provides a hierarchical coordinated control method for a hub motor drive system, comprising:

[0006] S1: Acquire pedal signals and vehicle operating status to identify and obtain total torque demand;

[0007] S2: Through the torque coordination controller, the total required torque is coordinated and allocated in a multi-objective manner to obtain independent torque commands from multiple hub motors;

[0008] S3: By executing multiple independent torque commands through multiple motor controllers, the actual output torque of multiple hub motors is obtained;

[0009] S4: Based on the actual output torque, the torque coordination controller performs fault diagnosis and reconstruction on the feedback information of multiple hub motors to obtain an updated torque distribution strategy;

[0010] S5: Control multiple hub motors based on the updated torque distribution strategy to complete the hierarchical coordinated control of the hub motor drive system.

[0011] According to the present invention, a hierarchical coordinated control method for a hub motor drive system is provided, wherein step S1 further includes:

[0012] S11: Collect accelerator pedal opening signal and brake pedal opening signal, and perform driving intention recognition to obtain initial torque demand;

[0013] S12: Collect operating signals and perform vehicle status evaluation through the vehicle controller to obtain current operating constraints; the operating signals include vehicle speed signal, battery SOC signal and gear signal;

[0014] S13: Calculate the torque requirement based on the initial torque requirement and the current operating constraints to obtain the total required torque.

[0015] According to the present invention, a hierarchical coordinated control method for a hub motor drive system, step S2 further includes:

[0016] S21: The total required torque is distributed between the front and rear axles through the basic allocation module to obtain the basic torque requirements of the front axle and the basic torque requirements of the rear axle, respectively.

[0017] S22: By analyzing the deviation between the actual yaw rate and the desired yaw rate through the yaw stability control module, the yaw torque compensation amount is obtained.

[0018] S23: The anti-slip control module performs anti-slip judgment on multiple wheel slip rate signals to obtain the anti-slip torque adjustment amount;

[0019] S24: The torque distribution module performs multi-objective optimization allocation of the basic torque requirements of the front axle and the basic torque requirements of the rear axle, the yaw moment compensation, and the anti-slip torque adjustment to obtain independent torque commands for multiple hub motors.

[0020] According to the present invention, a hierarchical coordinated control method for a hub motor drive system is provided, wherein step S22 further includes:

[0021] S221: Obtain the actual yaw rate using a yaw rate sensor;

[0022] S222: Calculate the desired yaw rate by using a vehicle dynamics model to calculate the steering wheel angle and vehicle speed;

[0023] S223: The deviation between the actual yaw rate and the desired yaw rate is analyzed by using a PID control algorithm to obtain the yaw torque compensation amount.

[0024] According to the present invention, a hierarchical coordinated control method for a hub motor drive system, step S23 further includes:

[0025] S231: Obtain wheel speed signals of multiple wheels through wheel speed sensors;

[0026] S232: The wheel rotation speed signal is processed by the vehicle speed estimation module to calculate the reference vehicle speed and obtain the reference vehicle speed.

[0027] S233: The slip ratio calculation module calculates the slip ratio of the wheel speed signal and the reference vehicle speed to obtain the wheel slip ratio of multiple wheels;

[0028] S234: The anti-slip torque adjustment amount is obtained by judging the wheel slip rate and adjusting the torque through the anti-slip control algorithm.

[0029] According to the present invention, a hierarchical coordinated control method for a hub motor drive system, step S4 further includes:

[0030] S41: The fault detection module performs anomaly detection on the controller status signals of multiple motor controllers to obtain fault diagnosis results; the controller status signals include communication status, motor temperature signal and current signal;

[0031] S42: The fault isolation module performs fault location and severity assessment on the fault diagnosis results to obtain fault isolation information;

[0032] S43: The updated torque allocation strategy is obtained by calculating the torque redistribution strategy based on the fault isolation information through the control reconfiguration module.

[0033] According to the present invention, a hierarchical coordinated control method for a hub motor drive system is provided, wherein step S43 specifically includes:

[0034] When a single wheel fails, the torque is redistributed to the remaining healthy wheel hub motors through the three-wheel drive reconfiguration algorithm to obtain the driving torque commands for the other wheels.

[0035] When multiple wheel hub motors fail, the limp mode algorithm is used to distribute the minimum safe torque to the other healthy hub motors to obtain the limp mode torque command.

[0036] The present invention also provides a hierarchical coordination control system for a hub motor drive system, comprising:

[0037] The vehicle controller is used to acquire pedal signals and vehicle operating status, and identify and obtain the total torque demand.

[0038] The torque coordination controller is communicatively connected to the vehicle controller and is used to perform multi-objective coordinated allocation processing on the total required torque, generate independent torque commands for multiple hub motors, and perform fault diagnosis and reconstruction processing on the feedback information of multiple hub motors to generate an updated torque allocation strategy.

[0039] Multiple motor controllers are each communicatively connected to the torque coordination controller, and are used to execute multiple independent torque commands respectively;

[0040] Multiple hub motors are connected to multiple motor controllers to output the actual drive torque based on the actual output torque.

[0041] According to the present invention, a hierarchical coordination control system for a hub motor drive system includes a torque coordination controller comprising:

[0042] The basic distribution module is used to distribute the total required torque between the front and rear axles.

[0043] The yaw stability control module is used to perform deviation analysis on the actual yaw angular velocity and the desired yaw angular velocity, and generate the yaw moment compensation amount.

[0044] The drive anti-slip control module is used to perform anti-slip judgment processing on multiple wheel slip rate signals and generate anti-slip torque adjustment amount;

[0045] The torque distribution module is used to perform multi-objective optimization and distribution of the basic torque requirements of the front and rear axles, the yaw moment compensation, and the anti-slip torque adjustment.

[0046] According to the present invention, a hierarchical coordination control system for a hub motor drive system, wherein the torque coordination controller further includes:

[0047] The fault detection module is used to detect and process anomalies in the communication status of multiple motor controllers, motor temperature signals, and current signals.

[0048] The fault isolation module is used to perform fault location and severity assessment on the fault diagnosis results output by the fault detection module.

[0049] The control reconfiguration module is used to calculate and process the torque redistribution strategy based on the fault isolation information output by the fault isolation module, generating an updated torque distribution strategy. This invention provides a hierarchical coordinated control method and system for a hub motor drive system. First, the vehicle controller performs vehicle-level decision processing on the driver's pedal signal and vehicle operating status to generate the total required torque, effectively reducing system complexity and significantly shortening control response time. This allows the vehicle to quickly respond to driver intentions under various operating conditions, thereby greatly improving the smoothness and comfort of the driving experience. Second, the torque coordination controller performs multi-objective coordinated distribution processing on the total required torque to obtain independent torque commands for the four hub motors, achieving precise independent control of the torque of each wheel. This precise control capability allows the vehicle to obtain optimal power distribution in various driving scenarios such as acceleration, braking, and cornering, significantly enhancing vehicle handling stability and driving safety. Simultaneously, by optimizing the operating point distribution of each motor, the overall system's energy utilization efficiency is effectively improved, extending the vehicle's range. Third, the yaw stability control module further optimizes the torque distribution. The actual yaw rate and the desired yaw rate are analyzed to generate a yaw torque compensation. The anti-slip control module analyzes the slip rate signals of each wheel to generate an anti-slip torque adjustment. This integrated application of coordinated control functions greatly enhances the vehicle's stability and safety on wet, slippery, icy, and snowy road conditions, effectively preventing loss of control and skidding, and providing drivers with safer and more reliable driving protection. Furthermore, this invention employs a complete fault diagnosis and reconstruction mechanism consisting of a fault detection module, a fault isolation module, and a control reconstruction module. This ensures that the system can maintain basic driving functions even when one or more components fail. High fault tolerance and system redundancy not only guarantee passenger safety but also significantly reduce the risk of complete vehicle failure due to malfunctions, reducing maintenance costs and downtime, improving vehicle reliability and practicality, and providing users with a more stable and economical travel experience. Attached Figure Description

[0050] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. It is obvious that the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings.

[0051] Figure 1 This is a schematic flowchart of a hierarchical coordinated control method for a hub motor drive system provided in an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of a hierarchical coordination control system for a hub motor drive system provided in an embodiment of the present invention. Detailed Implementation

[0053] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0054] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this invention.

[0055] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0056] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of methods and systems consistent with some aspects of the invention as detailed in the appended claims.

[0057] The embodiments of the present invention are described below with reference to the figures.

[0058] like Figure 1 As shown, the present invention first provides a hierarchical coordinated control method for a hub motor drive system, comprising:

[0059] S1: Acquire pedal signals and vehicle operating status to identify and obtain total torque demand.

[0060] Step S1 further includes:

[0061] S11: Collect accelerator pedal opening signal and brake pedal opening signal, and perform driving intention recognition to obtain initial torque demand.

[0062] Furthermore, in step S11, the present invention, based on the vehicle controller, receives the 0-5V voltage signal output by the accelerator pedal position sensor and the 0-5V voltage signal output by the brake pedal position sensor through an analog-to-digital converter. Subsequently, the voltage signals are converted into pedal opening values ​​of 0-100%. After conversion, dual-pedal state machine logic is used for processing. When the accelerator pedal opening is greater than 5% and the brake pedal opening is less than 2%, it is determined as an acceleration intention. Then, the accelerator pedal opening is mapped to the initial torque requirement through a lookup table method. When the brake pedal opening is greater than 2%, it is determined as a braking intention, and the initial torque requirement is set to a negative value. When both pedal openings are less than the threshold, the initial torque requirement is set to zero.

[0063] S12: Collect operating signals and perform vehicle status evaluation through the vehicle controller to obtain current operating constraints; the operating signals include vehicle speed signal, battery SOC signal and gear signal.

[0064] Furthermore, in step S12, the present invention, based on the vehicle controller, receives four pulse signals transmitted by the wheel speed sensors via the CAN bus. Each pulse represents a fixed angle of wheel rotation. The controller calculates the number of pulses per unit time to obtain the rotational speed of each wheel, and then takes the average of the four wheel speeds as the vehicle speed signal. For the battery SOC signal, the present invention, based on the battery management system, sends an SOC data packet to the vehicle controller via a dedicated communication line. The data packet contains the current remaining battery charge percentage, battery temperature, and voltage information. For the gear position signal, the present invention uses the digital signal input of the gear switch. The vehicle controller reads the binary code of the gear switch and decodes it into the corresponding gear position.

[0065] The subsequent vehicle status assessment involves determining the vehicle's operating status based on the vehicle speed signal. A speed below 5 km / h is defined as low speed, 5-60 km / h as medium speed, and above 60 km / h as high speed. Then, power constraints are set based on the SOC signal. Maximum power output is allowed when the SOC is above 80%, power decreases linearly between 20-80% of the SOC, and power output is limited to 50% of the rated power when the SOC is below 20%. Finally, the direction of torque output is determined based on the gear signal: torque is positive in forward gear, negative in reverse gear, and zero in neutral.

[0066] S13: Calculate the torque requirement based on the initial torque requirement and the current operating constraints to obtain the total required torque.

[0067] In step S13, the present invention uses an optimization algorithm under multiple constraints to calculate the torque demand. Specifically, firstly, the initial torque demand is matched with the vehicle speed state. At low speed, the torque demand is multiplied by a low-speed gain coefficient of 1.2 to provide better starting performance. At medium speed, the original value is maintained. At high speed, it is multiplied by a high-speed limit coefficient of 0.8 to ensure high-speed stability. Then, the torque demand is power-limited according to the SOC constraint condition to calculate the current maximum available torque. After obtaining the maximum available torque, the present invention compares the initial torque demand with the maximum available torque and takes the smaller value as the torque demand after power constraint. Next, the torque output direction is determined according to the gear signal. The value is kept positive when in forward gear and multiplied by -1 to obtain a negative torque when in reverse gear. Finally, the torque demand is checked by a safety limit algorithm to ensure that the torque value is within the rated torque range of the motor. If it exceeds the range, a cutoff process is performed to obtain the final total demand torque.

[0068] S2: Through the torque coordination controller, the total required torque is coordinated and allocated in a multi-objective manner to obtain independent torque commands for multiple hub motors.

[0069] Step S2 further includes:

[0070] S21: The total required torque is distributed between the front and rear axles through the basic allocation module to obtain the basic torque requirements of the front axle and the basic torque requirements of the rear axle.

[0071] In step S21, the basic torque distribution module receives the total torque demand value from the vehicle controller. First, it reads the preset front and rear axle torque distribution ratio parameters from the vehicle parameter memory. In normal mode, the front axle distribution ratio is set to 40%, and the rear axle distribution ratio is set to 60%. Internally, the module dynamically adjusts the distribution ratio based on the real-time vehicle speed signal. When the vehicle speed is below 30 km / h, the algorithm increases the front axle distribution ratio by 10% to 50%, and correspondingly decreases the rear axle distribution ratio by 10% to 50% to balance the front and rear axle traction distribution. When the vehicle speed exceeds 80 km / h, the algorithm decreases the front axle distribution ratio by 5% to 35%, and increases the rear axle distribution ratio by 5% to 65% to enhance the vehicle's high-speed stability. Finally, the basic torque distribution algorithm multiplies the total torque demand by the front axle distribution ratio to obtain the front axle basic torque demand, and multiplies the total torque demand by the rear axle distribution ratio to obtain the rear axle basic torque demand. These two values ​​are the output of the basic torque distribution module.

[0072] S22: By analyzing the deviation between the actual yaw rate and the desired yaw rate through the yaw stability control module, the yaw torque compensation amount is obtained.

[0073] Step S22 further includes:

[0074] S221: Obtain the actual yaw rate using a yaw rate sensor.

[0075] In step S221, the present invention uses a yaw rate sensor employing MEMS gyroscope technology to acquire the yaw rate. The sensor outputs an analog voltage signal of the yaw rate within the range of -500 to +500° / s. Subsequently, the torque coordination controller converts the analog voltage signal into a corresponding digital value through a 16-bit ADC. Since the original sensor data contains high-frequency noise and measurement errors, the controller also uses a Butterworth second-order low-pass digital filter to filter the data. The filter cutoff frequency is set to 50Hz. The filtering algorithm calculates the weighted average of the current sample value and the previous two sample values, and recursively calculates the data by combining the previous two filtered output values. The filtered data is then output as the actual yaw rate to the subsequent control module.

[0076] S222: The desired yaw rate is obtained by calculating the steering wheel angle and vehicle speed using a vehicle dynamics model.

[0077] In step S222, this invention uses a vehicle dynamics model based on two-degree-of-freedom vehicle dynamics theory to receive two input parameters: steering wheel angle and vehicle speed, and outputs the desired yaw rate. During the calculation, the steering wheel angle is first divided by the steering ratio 16 to obtain the front wheel angle. Then, the vehicle speed is multiplied by the front wheel angle to obtain the base yaw rate. The calculation considers the influence of the vehicle wheelbase of 2.8m and the understeer coefficient of 0.002s² / m². The base yaw rate is corrected by using the product of the wheelbase, the understeer coefficient, and the square of the vehicle speed as the denominator. When the vehicle speed exceeds 120km / h, this invention limits the desired yaw rate to within a maximum value of 3° / s, using a saturation limiting function for numerical cutoff processing.

[0078] S223: The deviation between the actual yaw rate and the desired yaw rate is analyzed by using a PID control algorithm to obtain the yaw torque compensation amount.

[0079] In step S223, the present invention receives two input signals—the actual yaw rate and the desired yaw rate—based on a PID control algorithm, and then calculates the deviation between them as the error input of the control algorithm. In the PID control algorithm, the proportional loop multiplies the deviation by a proportional coefficient of 800 Nm·s / rad to obtain the proportional control output; the integral loop performs time accumulation calculation on the deviation and multiplies it by an integral coefficient Ki=200 Nm / rad to obtain the integral control output; and the derivative loop calculates the rate of change of the deviation and multiplies it by a derivative coefficient Kd=50 Nm·s² / rad to obtain the derivative control output. Finally, the control outputs of the three loops are added together to obtain the final yaw moment compensation.

[0080] S23: The anti-slip control module performs anti-slip judgment on multiple wheel slip rate signals to obtain the anti-slip torque adjustment amount.

[0081] Step S23 further includes:

[0082] S231: Obtain wheel speed signals of multiple wheels through wheel speed sensors.

[0083] In step S231, this invention employs a wheel speed sensor based on Hall effect magnetoresistive sensor technology. Each wheel is equipped with one sensor to detect its rotational speed. The sensor tooth ring is designed with 48 equally spaced tooth grooves. Each time the wheel rotates one revolution, the tooth ring passes the sensor, generating 48 pulse signals. Subsequently, the frequency counter module inside the torque coordination controller counts the number of pulse signals received within a fixed time window, set to 10ms. The counter multiplies the number of pulses by 60, divides by 48, and then by the product of the time interval to obtain the wheel speed value in rpm. The controller simultaneously processes the pulse signals from all four wheels, calculating the speed data for each. The data update frequency is 100Hz, and the four speed values ​​are combined to form a wheel speed signal array for output.

[0084] S232: The reference vehicle speed is obtained by performing reference vehicle speed calculation on the wheel rotation speed signal through the vehicle speed estimation module.

[0085] In step S232, the present invention receives the rotational speed signal data of the four wheels based on the vehicle speed estimation module. First, the rotational speed of each wheel is multiplied by the wheel radius and then divided by 60 to obtain the linear velocity value of each wheel. Subsequently, a weighted average fusion algorithm is used to calculate the reference vehicle speed. The weight allocation is determined according to the front and rear axle load distribution of the vehicle, with the front wheel weight set to 0.4 and the rear wheel weight set to 0.6. After multiplying the linear velocities of the four wheels by their corresponding weight coefficients, the products are added together and then divided by the sum of the weight coefficients to obtain the reference vehicle speed. When an abnormal wheel rotational speed data is detected, the anomaly detection algorithm automatically sets the weight coefficient of that wheel to 0, and the weight coefficients of the remaining wheels are redistributed proportionally to ensure the accuracy of the reference vehicle speed calculation.

[0086] S233: The slip ratio calculation module calculates the slip ratio of the wheel speed signal and the reference vehicle speed to obtain the wheel slip ratio of multiple wheels.

[0087] In step S233, the present invention receives the rotational speed signals of each wheel and the reference vehicle speed value through a slip ratio calculation module, and then converts the rotational speed of each wheel into the corresponding wheel linear velocity. Specifically, the slip ratio calculation algorithm first compares the wheel linear velocity with the reference vehicle speed. When the wheel linear velocity is greater than the reference vehicle speed, it indicates that the wheel is experiencing driving slippage, and the slip ratio is positive. When the wheel linear velocity is less than the reference vehicle speed, it indicates that the wheel is experiencing braking slippage, and the slip ratio is negative. Subsequently, the difference between the wheel linear velocity and the reference vehicle speed is divided by the larger of the two to obtain the slip ratio value. The slip ratio value is limited to the range of -1 to +1. Finally, the module calculates the slip ratio of each of the four wheels and outputs a numerical array containing the slip ratios of the four wheels. The array update frequency is consistent with the wheel rotational speed signal at 100Hz.

[0088] S234: The anti-slip torque adjustment amount is obtained by judging the wheel slip rate and adjusting the torque through the anti-slip control algorithm.

[0089] In step S234, the present invention first receives the slip ratio numerical array of four wheels based on the anti-slip control algorithm, compares it with the preset slip ratio threshold of 0.15, and determines that the wheel has entered the slip state and starts the anti-slip control process when the absolute value of the slip ratio of a certain wheel exceeds the threshold.

[0090] In anti-slip control, the slip mode control method calculates the anti-slip torque adjustment amount based on the degree to which the slip rate exceeds a threshold. The control gain coefficient is set to 500 Nm. This invention takes the sign function value of the difference between the slip rate and the threshold, multiplies it by the 0.5 power of the absolute value of the difference and the control gain coefficient to obtain the anti-slip torque adjustment amount of the wheel. When multiple wheels slip simultaneously, the algorithm calculates the anti-slip torque adjustment amount of each slipping wheel separately, and sets the adjustment amount of non-slipping wheels to 0. Finally, the module outputs an array of anti-slip torque adjustment amounts, which contains the torque adjustment values ​​corresponding to the four wheels. A negative adjustment amount indicates that the driving torque of the wheel needs to be reduced.

[0091] S24: The torque distribution module performs multi-objective optimization allocation of the basic torque requirements of the front axle and the basic torque requirements of the rear axle, the yaw moment compensation, and the anti-slip torque adjustment to obtain independent torque commands for multiple hub motors.

[0092] In step S24, the present invention receives four sets of data based on the torque comprehensive distribution module: the front axle basic torque requirement, the rear axle basic torque requirement, the yaw moment compensation amount, and the anti-slip torque adjustment amount array, and performs comprehensive processing. Specifically, firstly, the basic torque demand of the front axle is evenly distributed to the left and right front wheels, and the basic torque demand of the rear axle is evenly distributed to the left and right rear wheels, obtaining the basic torque distribution value for each wheel. Then, the torque distribution of the left and right wheels is adjusted according to the yaw moment compensation amount. The yaw moment is achieved by creating a torque difference between the left and right wheels. The algorithm divides the yaw moment compensation amount by the wheel track and then by 2 to obtain the torque adjustment of a single wheel. The torque of the left wheel is increased by this adjustment amount, and the torque of the right wheel is decreased by this adjustment amount to achieve the desired yaw moment output. Next, the adjustment values ​​of each wheel in the anti-slip torque adjustment amount array are superimposed on the torque command of the corresponding wheel to obtain the torque distribution result including anti-slip control. Finally, the constraint processing algorithm checks whether the torque command of each wheel exceeds the rated torque range of the motor. If it exceeds the range, a proportional scaling method is used to reduce the torque command of all wheels to the allowable range by the same proportion, and the final independent torque command of the four hub motors is output.

[0093] S3: By executing multiple independent torque commands through multiple motor controllers, the actual output torque of multiple hub motors is obtained.

[0094] In step S3, this invention is based on each motor controller MCU receiving an independent torque command sent from the torque coordination controller TCU, and then parsing the data through each MCU configured with an independent CAN node ID. First, the instruction parsing module inside the MCU verifies and checks the received CAN frame. After confirming the data integrity, it extracts the torque command value and then converts the torque command into the corresponding motor current command. The conversion process is based on the motor torque constant. The current command is calculated by dividing the torque command by the torque constant. Subsequently, the current loop controller uses an adjustment algorithm to adjust the deviation between the actual motor current and the current command. The proportional coefficient Kp of the PI controller is set to 50A / V, and the integral coefficient Ki is set to 2000A / (V·s). The controller outputs a voltage command U_cmd to control the switching of the inverter transistors. Then, the voltage command is converted into a PWM duty cycle signal through the space vector pulse width modulation (SVPWM) algorithm. The PWM frequency is set to 10kHz. The inverter drives the permanent magnet synchronous motor (PMSM) to output the actual torque according to the PWM signal. Finally, the MCU detects the three-phase current of the motor through a current sensor, detects the rotor position and speed of the motor through a resolver sensor, and calculates the actual output torque T_actual value by combining the motor torque constant.

[0095] S4: Based on the actual output torque, the torque coordination controller performs fault diagnosis and reconstruction on the feedback information of multiple hub motors to obtain an updated torque distribution strategy.

[0096] Step S4 further includes:

[0097] S41: The fault detection module performs anomaly detection on the controller status signals of multiple motor controllers to obtain fault diagnosis results; the controller status signals include communication status, motor temperature signal and current signal.

[0098] In step S41, the fault detection module receives controller status signal data packets sent by four MCUs. These data packets contain three types of information: communication status flags, motor temperature signals, and current signals. The communication status detection algorithm monitors the CAN frame reception timestamp of each MCU. If a status frame from a certain MCU is not received for 100 consecutive ms, that MCU is marked as having a communication timeout fault, with the fault code set to 0x01. The corresponding motor temperature signal is obtained through an NTC thermistor sensor. The sensor outputs a 0-5V analog voltage signal, and the MCU's internal ADC converts the voltage signal into a temperature value, with a temperature range of -40°C to +180°C. In this invention, the fault detection algorithm sets a temperature threshold of 150℃. When the motor temperature exceeds this threshold, it is marked as an over-temperature fault, and the fault code is set to 0x02. Current signal detection uses a Hall effect current sensor to monitor the three-phase current of the motor. The sensor outputs a voltage signal proportional to the current. The MCU converts the voltage signal into an effective current value. After receiving the signal, this invention compares the effective current value with the motor's rated current of 300A. When the current exceeds 120% of the rated current, i.e., 360A, it is marked as an overcurrent fault, and the fault code is set to 0x03. Finally, the detection module combines the fault states of each MCU into a fault diagnosis result array. The array contains four elements corresponding to the fault information of the FL, FR, RL, and RR wheels, respectively.

[0099] S42: The fault diagnosis results are used to locate the fault and assess its severity through the fault isolation module to obtain fault isolation information.

[0100] In step S42, the fault isolation module receives the fault diagnosis result array and analyzes each fault code to determine the fault location and severity. This invention uses a fault location algorithm to determine the specific fault location based on the fault code. A communication timeout fault is located as an MCU controller fault, an over-temperature fault as a motor body fault, and an overcurrent fault as a motor or load fault. The severity assessment algorithm classifies faults into three levels: minor faults (Level 1) allow continued operation but require monitoring; moderate faults (Level 2) require reduced power operation; and severe faults (Level 3) require immediate shutdown. Communication timeout and overcurrent faults are assessed as Level 3 severe faults. Over-temperature faults are graded based on temperature values: 150-160°C is assessed as Level 2 moderate faults, and above 160°C is assessed as Level 3 severe faults. The fault isolation module generates a fault isolation information structure based on the fault location and severity. The structure includes four fields: fault wheel position identifier, fault type code, severity level, and timestamp. When multiple faults are detected, the module outputs a fault isolation information array sorted by severity.

[0101] S43: The updated torque allocation strategy is obtained by calculating the torque redistribution strategy based on the fault isolation information through the control reconfiguration module.

[0102] Specifically, step S43 includes: when a single wheel fails, the torque of the remaining healthy wheel hub motors is redistributed through the three-wheel drive reconfiguration algorithm to obtain the driving torque command for the other wheels; when multiple wheels fail, the minimum safe torque is allocated to the other healthy wheel hub motors through the limp mode algorithm to obtain the limp mode torque command.

[0103] In step S43, the control reconfiguration module receives fault isolation information, counts the number of fault wheels, and selects the corresponding reconfiguration algorithm based on the statistical results.

[0104] When there is one faulty wheel, the three-wheel drive reconfiguration algorithm initiates the processing flow. Specifically, it first sets the torque command of the faulty wheel to 0, then redistributes the total required torque. When a front wheel fails, the torque originally allocated to the faulty front wheel is transferred to the opposite front and rear wheels, with a transfer ratio of 30% to the opposite front wheel and 35% to each of the two rear wheels. When a rear wheel fails, the torque originally allocated to the faulty rear wheel is transferred to the opposite rear and front wheels, with a transfer ratio of 50% to the opposite rear wheel and 25% to each of the two front wheels. Subsequently, the reconfiguration algorithm also considers the torque carrying capacity limitations of the remaining three wheels. When the redistributed torque exceeds the rated torque of a wheel, a proportional scaling method is used to reduce the total required torque proportionally.

[0105] When the number of faulty wheels is greater than or equal to two, the limp mode algorithm initiates the processing flow. Specifically, the total torque demand is limited to within 30% of the original demand, prioritizing the driving capability of diagonal wheels. If the front left wheel and rear right wheel are faulty, the front right wheel and rear left wheel will be used first, and vice versa. In limp mode, the torque command for each healthy wheel will not exceed 50% of the rated torque, and the vehicle speed is limited to within 30 km / h. The reconstruction module outputs an updated torque distribution strategy data structure, containing the new torque commands for the four wheels and the working mode flag.

[0106] S5: Control multiple hub motors based on the updated torque distribution strategy to complete the hierarchical coordinated control of the hub motor drive system.

[0107] In step S5, the torque coordination controller controls the hub motors according to the updated torque distribution strategy. The controller first reads the operating mode flag in the updated torque distribution strategy. In normal mode, it continues the regular control process. In three-wheel drive mode, it continuously sends a torque command of 0 to the MCU of the faulty wheel and monitors its status. In limp mode, it simultaneously sends a power reduction request and speed limit command to the vehicle controller (VCU). Then, the controller sends the updated four-wheel torque command to the corresponding MCU via the CAN bus, maintaining a transmission frequency of 100Hz. Simultaneously, the controller starts the faulty wheel status monitoring program, checking every 500ms whether the faulty wheel has recovered. Once the fault is cleared, it automatically exits the reconfiguration mode and resumes normal four-wheel drive. Additionally, the controller sends a system status report to the VCU, which includes information such as the current operating mode, faulty wheel information, remaining drive capacity percentage, and estimated recovery time. The VCU adjusts the vehicle control strategy based on this report and displays corresponding fault indication information to the driver.

[0108] like Figure 2 As shown, the present invention also provides a hierarchical coordination control system for a hub motor drive system, comprising:

[0109] The vehicle controller 100 is used to acquire pedal signals and vehicle operating status, and to identify and obtain the total required torque.

[0110] The torque coordination controller 200 is communicatively connected to the vehicle controller 100. It is used to perform multi-objective coordinated allocation processing on the total demand torque, generate independent torque commands for multiple wheel hub motors, and perform fault diagnosis and reconstruction processing on the feedback information of multiple wheel hub motors to generate an updated torque allocation strategy.

[0111] Multiple motor controllers 300 are communicatively connected to the torque coordination controller 200, and are used to execute multiple independent torque commands respectively;

[0112] Multiple hub motors 400 are connected to multiple motor controllers 300 respectively, and are used to output the actual drive torque according to the actual output torque.

[0113] The torque coordination controller 200 includes:

[0114] The basic distribution module is used to distribute the total required torque between the front and rear axles.

[0115] The yaw stability control module is used to perform deviation analysis on the actual yaw angular velocity and the desired yaw angular velocity, and generate the yaw moment compensation amount.

[0116] The drive anti-slip control module is used to perform anti-slip judgment processing on multiple wheel slip rate signals and generate anti-slip torque adjustment amount;

[0117] The torque distribution module is used to perform multi-objective optimization and distribution of the basic torque requirements of the front and rear axles, the yaw moment compensation, and the anti-slip torque adjustment.

[0118] The torque coordination controller 200 further includes:

[0119] The fault detection module is used to detect and process anomalies in the communication status of multiple motor controllers, motor temperature signals, and current signals.

[0120] The fault isolation module is used to perform fault location and severity assessment on the fault diagnosis results output by the fault detection module.

[0121] The control reconfiguration module is used to perform torque redistribution strategy calculation and processing on the fault isolation information output by the fault isolation module, and generate an updated torque distribution strategy.

[0122] In a specific implementation of the layered coordination control system for a hub motor drive system of the present invention, the VCU, TCU, and MCU are all embedded electronic control units (ECUs), including microprocessors, memory, communication interfaces (CAN / CAN FD / Ethernet), and input / output interfaces. The TCU needs to have strong real-time computing capabilities (such as using a multi-core MCU or DSP). The hub motor is a permanent magnet synchronous motor (PMSM) or an asynchronous motor (IM), equipped with a resolver sensor or encoder. Vehicle status sensors include wheel speed sensors, yaw rate sensors (gyroscopes), steering wheel angle sensors, acceleration sensors, battery management systems (BMS), etc. The communication bus used is a high-speed bus such as CAN FD (5 Mbps) or AutomotiveEthernet (100 Mbps) to meet real-time requirements.

[0123] This invention significantly reduces the computational load on the vehicle controller through a hierarchical coordinated control architecture. The introduction of a dedicated torque coordination controller greatly shortens the system response time, enabling the vehicle to respond quickly and accurately to driving commands even under complex operating conditions. Secondly, this invention integrates multiple functions such as basic allocation, yaw stability control, and drive anti-slip control through a multi-objective coordinated allocation algorithm, greatly enhancing the vehicle's driving stability and safety in dangerous situations such as slippery roads and emergency lane changes. In addition, a comprehensive fault diagnosis and reconfiguration mechanism ensures that the system can maintain basic driving functions even when one or more components fail, effectively avoiding the risk of the vehicle completely losing power due to local faults. Furthermore, precise torque distribution control significantly improves the vehicle's acceleration performance and handling response, while optimizing the distribution of the operating points of each motor effectively improves the overall energy efficiency of the system.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention 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; and these 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 the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A hierarchical coordinated control method for a hub motor drive system, characterized in that, include: S1: Acquire pedal signals and vehicle operating status to identify and obtain total torque demand; S2: Through the torque coordination controller, the total required torque is coordinated and allocated in a multi-objective manner to obtain independent torque commands from multiple hub motors; S3: By executing multiple independent torque commands through multiple motor controllers, the actual output torque of multiple hub motors is obtained; S4: Based on the actual output torque, the torque coordination controller performs fault diagnosis and reconstruction on the feedback information of multiple hub motors to obtain an updated torque distribution strategy; Step S4 further includes: S41: performing anomaly detection on the controller status signals of multiple motor controllers through a fault detection module to obtain fault diagnosis results; the controller status signals include communication status, motor temperature signals, and current signals; S42: performing fault location and severity assessment on the fault diagnosis results through a fault isolation module to obtain fault isolation information; S43: performing torque redistribution strategy calculation on the fault isolation information through a control reconfiguration module to obtain the updated torque distribution strategy; Specifically, step S43 includes: when a single wheel fails, the torque of the remaining healthy wheel hub motors is redistributed through the three-wheel drive reconfiguration algorithm to obtain the driving torque command for the other wheels; when multiple wheels fail, the minimum safe torque is allocated to the other healthy wheel hub motors through the limp mode algorithm to obtain the limp mode torque command. In the aforementioned wheel drive reconfiguration algorithm, when a single wheel fails, the torque command for the failed wheel is set to 0, and the total required torque is redistributed. Specifically, when the single wheel failure is a front wheel failure, the torque allocated to the failed front wheel is transferred to the opposite front wheel and both rear wheels, with a transfer ratio of 30% to the opposite front wheel and 35% to each of the two rear wheels; when the single wheel failure is a rear wheel failure, the torque allocated to the failed rear wheel is transferred to the opposite rear wheel and both front wheels, with a transfer ratio of 50% to the opposite rear wheel and 25% to each of the two front wheels. In the limp mode algorithm, when multiple wheels fail, the total torque demand is limited to 30% of the demand before the failure, and the driving capability of the diagonal wheels is guaranteed first. In limp mode, the torque command of multiple healthy wheels does not exceed 50% of the rated torque, and the vehicle speed is limited to 30km / h. S5: Control multiple hub motors based on the updated torque distribution strategy to complete the hierarchical coordinated control of the hub motor drive system.

2. The hierarchical coordinated control method for a hub motor drive system according to claim 1, characterized in that, Step S1 further includes: S11: Collect accelerator pedal opening signal and brake pedal opening signal, and perform driving intention recognition to obtain initial torque demand; S12: Collect operating signals and perform vehicle status evaluation through the vehicle controller to obtain current operating constraints; the operating signals include vehicle speed signal, battery SOC signal and gear signal; S13: Calculate the torque requirement based on the initial torque requirement and the current operating constraints to obtain the total required torque.

3. The hierarchical coordinated control method for a hub motor drive system according to claim 1, characterized in that, Step S2 further includes: S21: The total required torque is distributed between the front and rear axles through the basic allocation module to obtain the basic torque requirements of the front axle and the basic torque requirements of the rear axle, respectively. S22: By analyzing the deviation between the actual yaw rate and the desired yaw rate through the yaw stability control module, the yaw torque compensation amount is obtained. S23: The anti-slip control module performs anti-slip judgment on multiple wheel slip rate signals to obtain the anti-slip torque adjustment amount; S24: The torque distribution module performs multi-objective optimization allocation of the basic torque requirements of the front axle and the basic torque requirements of the rear axle, the yaw moment compensation, and the anti-slip torque adjustment to obtain independent torque commands for multiple hub motors.

4. The hierarchical coordinated control method for a hub motor drive system according to claim 3, characterized in that, Step S22 further includes: S221: Obtain the actual yaw rate using a yaw rate sensor; S222: Calculate the desired yaw rate by using a vehicle dynamics model to calculate the steering wheel angle and vehicle speed; S223: The deviation between the actual yaw rate and the desired yaw rate is analyzed by using a PID control algorithm to obtain the yaw torque compensation amount.

5. The hierarchical coordinated control method for a hub motor drive system according to claim 3, characterized in that, Step S23 further includes: S231: Obtain wheel speed signals of multiple wheels through wheel speed sensors; S232: The wheel rotation speed signal is processed by the vehicle speed estimation module to calculate the reference vehicle speed and obtain the reference vehicle speed. S233: The slip ratio calculation module calculates the slip ratio of the wheel speed signal and the reference vehicle speed to obtain the wheel slip ratio of multiple wheels; S234: The anti-slip torque adjustment amount is obtained by judging the wheel slip rate and adjusting the torque through the anti-slip control algorithm.

6. A hierarchical coordinated control system for a hub motor drive system based on the hierarchical coordinated control method for a hub motor drive system as described in claim 1, characterized in that, include: The vehicle controller is used to acquire pedal signals and vehicle operating status, and identify and obtain the total torque demand. The torque coordination controller is communicatively connected to the vehicle controller and is used to perform multi-objective coordinated allocation processing on the total required torque, generate independent torque commands for multiple hub motors, and perform fault diagnosis and reconstruction processing on the feedback information of multiple hub motors to generate an updated torque allocation strategy. Multiple motor controllers are each communicatively connected to the torque coordination controller, and are used to execute multiple independent torque commands respectively; Multiple hub motors are connected to multiple motor controllers to output the actual drive torque based on the actual output torque.

7. The hierarchical coordination control system for the hub motor drive system according to claim 6, characterized in that, The torque coordination controller includes: The basic distribution module is used to distribute the total required torque between the front and rear axles. The yaw stability control module is used to perform deviation analysis on the actual yaw angular velocity and the desired yaw angular velocity, and generate the yaw moment compensation amount. The drive anti-slip control module is used to perform anti-slip judgment processing on multiple wheel slip rate signals and generate anti-slip torque adjustment amount; The torque distribution module is used to perform multi-objective optimization and distribution of the basic torque requirements of the front and rear axles, the yaw moment compensation, and the anti-slip torque adjustment.

8. The hierarchical coordination control system for the hub motor drive system according to claim 6, characterized in that, The torque coordination controller also includes: The fault detection module is used to detect and process anomalies in the communication status of multiple motor controllers, motor temperature signals, and current signals. The fault isolation module is used to perform fault location and severity assessment on the fault diagnosis results output by the fault detection module; the control reconfiguration module is used to perform torque redistribution strategy calculation on the fault isolation information output by the fault isolation module and generate an updated torque distribution strategy.

Images