Method and system for banding speed start control for distributed wheel motor / hub motor

Abstract

The application belongs to the technical field of electric vehicles, and particularly relates to a speed-starting control method and system for a distributed wheel-side / hub motor. The method comprises S1, a wheel-side / hub motor speed-starting power-off coasting stage processing process; S2, a wheel-side / hub motor speed-starting preparation stage processing process; S3, a wheel-side / hub motor speed-starting current tracking stage processing process; S4, a wheel-side / hub motor speed-starting speed tracking stage processing process; and S5, a wheel-side / hub motor speed-starting stable operation stage processing process. The application is applicable to non-stopping conditions, has the characteristics that no additional voltage sensor and speed sensor signals are needed, and only signals from inherent motor phase line end current sensors are needed to realize reliable power-on operation in a speed-starting state.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle technology, specifically relating to a speed-start control method and system for distributed wheel-side / hub motors. Background Technology

[0002] Distributed wheel-side motors or hub motors represent the future development direction for light electric vehicles. Distributed direct drive integrates the vehicle's power, transmission, and braking systems, simplifying the complex mechanical transmission structure, reducing overall vehicle weight, and allowing direct transmission of motor power to the corresponding wheels, resulting in higher transmission efficiency. However, when the vehicle is running at low speeds under heavy loads, the heat generated by the motor is difficult to dissipate, potentially triggering overheat protection. Furthermore, because the wheels are rigidly connected to the hub motors, significant vibrations from bumpy roads can affect the wheel speed sensors, triggering overcurrent protection in the motor controller. When the drive motor or controller of a particular drive wheel experiences overheat or overcurrent protection, the system typically disconnects the faulty motor from the powertrain, relying on the remaining drive wheels to provide the target driving force. As the vehicle continues to travel, the motor gradually cools down and exits the protection state, and the wheel speed sensors self-recover after the road surface returns to normal. The faulty drive wheel can be re-energized and restarted when it has speed, but this process can easily cause instantaneous torque surges and sudden speed changes in the motor, potentially leading to driving safety issues.

[0003] Existing permanent magnet motor speed-start technology solutions are divided into two categories: those relying on wheel speed sensors and those not relying on wheel speed sensors. When wheel speed sensors are available, current and speed control can be achieved at the moment of power-on based on speed / position signals. However, when wheel speed sensors are not in normal operating condition, current and speed control need to be achieved through sensorless algorithms.

[0004] Sensorless observation methods are mainly divided into high-frequency signal injection methods and back-EMF model methods. For example, the high-frequency injection IPMSM belt-speed restart control method based on control power supply described in patent publication CN113078866A estimates the motor speed and position at power-on by solving the current response. It has good signal identification performance at low speeds, but at high speeds, the limited observer bandwidth required for high-frequency signal analysis and the potential limitation of the inverter's output voltage upper limit on the amplitude of the injected voltage pulse restrict its identification accuracy and control performance at high speeds. In addition, patent publications CN109379007A and CN114362620A disclose two sensorless estimation methods based on back-EMF observation for implementing belt-speed restart control of independent single motors. Patent document CN109379007A uses redundant voltage sensors to collect motor terminal voltage signals to obtain the initial position and speed information of the motor rotor. A Luenberger observer is then used to estimate the motor rotor position and speed, achieving a smooth transition from the initial value to the observed value. However, the redundant voltage sensors increase system cost. Patent document CN114362620A, on the other hand, uses a short-circuit test pulse injection method to obtain the initial position and speed of the motor rotor at power-on and employs dual closed-loop control of speed and current to achieve power-on restart. Both of these belt-speed starting schemes are effective in the high-speed range, but require other methods in the low-speed range. Therefore, a single belt-speed restart method for a single motor is not universally applicable across the entire speed range and requires the combination of multiple control methods.

[0005] Based on the above problems, it is very important to design a belt-speed start control method and system for distributed wheel-side / hub motors that is applicable under non-stop conditions, does not rely on additional voltage and speed sensor signals, and only needs to obtain signals from the inherent motor phase line current sensor to achieve reliable power-on operation under belt speed conditions. Summary of the Invention

[0006] This invention aims to overcome the problem in the prior art where a sudden non-destructive failure in a multi-wheel drive system during vehicle operation causes the drive motor to shut down for protection, and the motor cannot provide driving force again after the fault disappears, thus affecting the overall driving performance of the vehicle. It provides a belt-speed start control method and system for distributed wheel-side / hub motors that is applicable under non-stop conditions, requiring no additional voltage and speed sensor signals, and only needing to obtain signals from the inherent motor phase current sensor to achieve reliable power-on operation under belt speed conditions.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A speed-start control method for distributed wheel-side / hub motors includes at least two independent drive units. Each drive unit includes a wheel-side permanent magnet motor or a hub permanent magnet motor, a wheel speed sensor, a current sensor, a signal acquisition circuit, a main controller, and a power inverter circuit. The wheel speed sensor is coaxially connected to the drive unit or connected via gear meshing. The current sensor is located on the motor three-phase output side of the power inverter circuit. The signal acquisition circuit is electrically connected to both the wheel speed sensor and the current sensor. The main controller is electrically connected to both the signal acquisition circuit and the power inverter circuit. The method includes the following steps.

[0009] S1, Wheel-side / hub motor coasting phase with power loss:

[0010] During the speed-loss coasting phase of the wheel-side / hub motor, the motor triggers a protection mechanism due to instantaneous overcurrent, overheating, or unstable wheel speed sensor signal. The drive circuit shuts down, causing the motor to lose power. The wheel is then dragged by the drive wheel, and the motor current is 0. The motor speed signal is unavailable, and the motor is in an electrically runaway state.

[0011] S2, Wheel-side / Hub Motor Speed-Drive Start-up Preparation Stage:

[0012] In the preparatory stage of the wheel-side / hub motor's belt-speed start-up, a constant current-frequency ratio (IF) control method is adopted, setting the initial expected values ​​of the d-axis and q-axis currents in the main controller's current loop control program to zero. As the current command for IF control, it simultaneously acquires the motor speed signal of the drive wheel and takes the average value of the electric angular velocity of the drive wheel as... As the frequency command for the IF control method; setting the current phase angle θ r0 =0, serving as the initial phase for the IF control method; simultaneously, the initial motor speed in the main controller's speed loop control program is set to...

[0013] S3, Wheel-side / Hub Motor Speed-up Starting Current Tracking Stage:

[0014] During the on-speed starting current tracking phase of the wheel-side / hub motor, the main controller activates the PWM control signal of the power inverter circuit, implementing a rotation frequency of... The IF control strategy uses proportional-integral-resonant closed-loop control to achieve rapid tracking and impact suppression of the motor's d-axis and q-axis currents, and the command voltage is obtained by observing the motor vector control model. and The power inverter circuit outputs a command voltage to the motor and further generates current.

[0015] S4, Wheel-side / hub motor speed-tracking start-up phase:

[0016] After the rapid current tracking process in step S3 stabilizes, the current motor speed and rotor angle are obtained through a sensorless estimation algorithm. The estimated motor speed is used as the feedback value of the speed closed loop, and the estimated rotor angle is used as the rotation angle of the dq coordinate system. The phase current measurement value is substituted into the dq coordinate transformation to calculate the feedback value of the current closed loop. Then, the control mode is quickly switched from the IF control of speed open loop and current closed loop to speed and current dual closed loop to achieve speed tracking.

[0017] S5, stable operation phase of wheel-side / hub motor with speed start:

[0018] The motor that is already running normally is put back into the vehicle's powertrain. The main controller receives torque distribution signals and speed signals from the vehicle's master controller and implements multi-wheel coordinated control of the vehicle. At the same time, the main controller detects non-destructive faults such as instantaneous overcurrent, overheating or wheel speed sensor signal instability in the motor drive system in real time. If the fault occurs again, steps S1 to S5 are repeated.

[0019] Preferably, the desired current signal i controlled by IF in steps S2 and S3 is... f All are represented as

[0020]

[0021] Let t be the expected value of the current along the q-axis in the dq coordinate system, and t be time.

[0022] Preferably, the transfer function of the proportional-integral-resonant closed-loop control described in step S3 is:

[0023]

[0024] Where k p k i k r These are the proportional coefficient, integral coefficient, and resonance coefficient, respectively; ω c ω d Here, ω represents the resonant angular frequency and resonant bandwidth, respectively, and s is the complex frequency in the Laplace transform; the resonant control frequency of the proportional-integral-resonant element in the current closed-loop control is set to ω. This is used to improve the phase tracking effect of AC current and AC voltage, and reduce overcurrent caused by the phase mismatch between the motor's rotating back EMF and the initial voltage of the power inverter circuit during startup; during belt-speed startup, the proportional-integral control parameter k is set. p k i To suppress the amplitude of the inrush current, the resonant control element coefficient k is set. r ω c ω dTo reduce phase tracking deviation of the alternating current, the resonant frequency ω of the resonant circuit needs to be updated in real time according to changes in wheel speed. c It is used to improve the dynamic tracking performance of the current controller.

[0025] Preferably, during step S4, the AC frequency of the motor current changes synchronously with the motor speed and vehicle speed, and the electric angular velocity of the motor is estimated by a sensorless estimation algorithm. Let the resonant frequency and resonant bandwidth of the resonant circuit be respectively...

[0026]

[0027] This is used to reduce the amplitude and phase errors in current tracking, achieving optimal tracking of sinusoidal AC current; among which The amplitude of the fluctuation in the estimated angular velocity;

[0028] According to formulas (2) and (3), the improved transfer function of the quasi-resonant element is obtained as follows:

[0029]

[0030] Preferably, the sensorless estimation algorithm includes rotor position estimation. and angular velocity The estimation calculation is specifically expressed as follows:

[0031]

[0032]

[0033]

[0034] Where, ψ α ψ β u α u β i α i β Represent the motor flux linkage, voltage, and current in the α-β coordinate system, respectively, R s L s These are the motor stator resistance and inductance, respectively, and LPF is a low-pass filter.

[0035] The present invention also provides a belt-start control system for distributed wheel-side / hub motors, comprising:

[0036] The wheel-side / hub motor speed-off coasting module is used to set up a protection mechanism that is triggered when the motor is subjected to instantaneous overcurrent, overheating or wheel speed sensor signal instability during the wheel-side / hub motor speed-off coasting phase. The drive circuit is shut down to de-energize the motor, and the wheel is dragged by the drive wheel to coast.

[0037] The wheel-side / hub motor speed-start preparation module is used to set the initial expected values ​​of the d-axis and q-axis currents in the main controller's current loop control program to zero, employing a constant current-frequency ratio (IF) control method. As the current command for IF control, it simultaneously acquires the motor speed signal of the drive wheel and takes the average value of the electric angular velocity of the drive wheel as... As the frequency command for the IF control method; setting the current phase angle θ r0 =0, serving as the initial phase for the IF control method; simultaneously, the initial motor speed in the main controller's speed loop control program is set to...

[0038] The wheel-side / hub motor speed-up current tracking module is used to enable the main controller to activate the PWM control signal of the power inverter circuit during the speed-up current tracking phase of the wheel-side / hub motor, thereby implementing a rotation frequency of... The IF control strategy uses proportional-integral-resonant closed-loop control to achieve rapid tracking and impact suppression of the motor's d-axis and q-axis currents, and the command voltage is obtained by observing the motor vector control model. and The power inverter circuit outputs a command voltage to the motor and further generates current.

[0039] The wheel-side / hub motor with speed-up starting speed tracking module is used to obtain the current motor speed and rotor angle through a sensorless estimation algorithm after the rapid current tracking process has stabilized. The estimated motor speed value is used as the feedback value of the speed closed loop, and the estimated rotor angle value is used as the rotation angle of the dq coordinate system. The phase current measurement value is substituted into the dq coordinate transformation to calculate the feedback value of the current closed loop. Then, the control mode is quickly switched from the speed open-loop and current closed-loop IF control to the speed and current dual closed loop to achieve speed tracking.

[0040] The wheel-side / hub motor speed-start and stable operation module is used to re-engage the motor that is already running normally into the vehicle's powertrain. The main controller receives torque distribution signals and speed signals from the vehicle's master controller to implement multi-wheel coordinated control of the vehicle. At the same time, the main controller detects non-destructive faults in the motor drive system, such as instantaneous overcurrent, overheating, or wheel speed sensor signal instability, in real time.

[0041] As a preferred embodiment, in the wheel-side / hub motor speed-off coasting module, the specific state of the motor is as follows: the motor current is 0, the motor speed signal is unavailable, and the motor is in an electrically runaway state.

[0042] Compared with the prior art, the beneficial effects of this invention are: (1) This invention proposes a method for starting a hub motor drive system with speed without voltage and position sensors, aiming to achieve safe power-on of the motor drive controller during vehicle operation without stopping and restarting; (2) This invention addresses the redundant structural characteristics of distributed electric vehicle multi-wheel drive systems, obtains the initial speed signal of the motor by means of the wheel speed sensor signal of the redundant wheels, and uses a proportional-integral-resonant (PIR) controller to achieve stable tracking of AC current and AC voltage, realizing power-on restart in the full speed domain; the PIR controller has tracking suppression characteristics for steady-state error of specific frequency signals, which can effectively suppress the motor current surge in the initial stage of power-on startup, improve the dynamic tracking performance of the current loop, and enable the hub motor cut off from the power chain to reliably and smoothly engage the power chain at different speeds; (3) This invention does not rely on additional voltage and speed sensor signals, but only needs to obtain signals from the inherent motor phase line current sensor to achieve reliable power-on operation under speed conditions, which is particularly suitable for wheel speed sensor failure. Attached Figure Description

[0043] Figure 1 This is a flowchart of a belt-speed start control method for distributed wheel-side / hub motors in this invention;

[0044] Figure 2 This is a topology diagram of the permanent magnet motor drive control system in this invention;

[0045] Figure 3 This is a schematic diagram of a PIR current controller in this invention;

[0046] Figure 4 This is a motor current waveform diagram for steps S1 to S5 of the high-speed start-up process in this invention;

[0047] Figure 5 This is a motor current waveform diagram for step S2 in the current tracking process of this invention;

[0048] Figure 6 This is a motor current waveform diagram for step S3 in the current tracking process of this invention. Detailed Implementation

[0049] To more clearly illustrate the embodiments of the present invention, specific implementation methods will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0050] Example:

[0051] like Figure 1 As shown, this invention provides a speed-start control method for distributed wheel-side / hub motors, comprising at least two independent drive units. Each drive unit includes a wheel-side permanent magnet motor or a hub permanent magnet motor, a wheel speed sensor, a current sensor, a signal acquisition circuit, a main controller, and a power inverter circuit. The wheel speed sensor is coaxially connected to the drive unit or connected via gear meshing. The current sensor is located on the motor three-phase output side of the power inverter circuit. The signal acquisition circuit is electrically connected to both the wheel speed sensor and the current sensor. The main controller is electrically connected to both the signal acquisition circuit and the power inverter circuit. The method includes the following steps.

[0052] S1, Wheel-side / hub motor coasting phase with power loss:

[0053] During the speed-loss coasting phase of the wheel-side / hub motor, the motor triggers a protection mechanism due to instantaneous overcurrent, overheating, or unstable wheel speed sensor signal. The drive circuit shuts down, causing the motor to lose power. The wheel is then dragged by the drive wheel, and the motor current is 0. The motor speed signal is unavailable, and the motor is in an electrically runaway state.

[0054] S2, Wheel-side / Hub Motor Speed-Drive Start-up Preparation Stage:

[0055] In the preparatory stage of the wheel-side / hub motor's belt-speed start-up, a constant current-frequency ratio (IF) control method is adopted, setting the initial expected values ​​of the d-axis and q-axis currents in the main controller's current loop control program to zero. As the current command for IF control, it simultaneously acquires the motor speed signal of the drive wheel and takes the average value of the electric angular velocity of the drive wheel as... As the frequency command for the IF control method; setting the current phase angle θ r0 =0, serving as the initial phase for the IF control method; simultaneously, the initial motor speed in the main controller's speed loop control program is set to...

[0056] S3, Wheel-side / Hub Motor Speed-up Starting Current Tracking Stage:

[0057] During the on-speed starting current tracking phase of the wheel-side / hub motor, the main controller activates the PWM control signal of the power inverter circuit, implementing a rotation frequency of... The IF control strategy uses proportional-integral-resonant closed-loop control to achieve rapid tracking and impact suppression of the motor's d-axis and q-axis currents, and the command voltage is obtained by observing the motor vector control model. and The power inverter circuit outputs a command voltage to the motor and further generates current.

[0058] S4, Wheel-side / hub motor speed-tracking start-up phase:

[0059] After the rapid current tracking process in step S3 stabilizes, the current motor speed and rotor angle are obtained through a sensorless estimation algorithm. The estimated motor speed is used as the feedback value of the speed closed loop, and the estimated rotor angle is used as the rotation angle of the dq coordinate system. The phase current measurement value is substituted into the dq coordinate transformation to calculate the feedback value of the current closed loop. Then, the control mode is quickly switched from the IF control of speed open loop and current closed loop to speed and current dual closed loop to achieve speed tracking.

[0060] S5, stable operation phase of wheel-side / hub motor with speed start:

[0061] The motor that is already running normally is put back into the vehicle's powertrain. The main controller receives torque distribution signals and speed signals from the vehicle's master controller and implements multi-wheel coordinated control of the vehicle. At the same time, the main controller detects non-destructive faults such as instantaneous overcurrent, overheating or wheel speed sensor signal instability in the motor drive system in real time. If the fault occurs again, steps S1 to S5 are repeated.

[0062] Figure 1 In the above, S1 is the speed-down coasting stage, and the switching condition ① is that the main controller detects a system fault and triggers the protection logic; S2 is the speed-start preparation stage, and the switching condition ② is that the system recovers from the fault state and the protection can be released; S3 is the speed-start current tracking stage, and the switching condition ③ is that the main controller has completed the speed-start initialization; S4 is the speed-start speed tracking stage, and the switching condition ④ is that the current loop tracking process of the system has stabilized; S5 is the speed-start stable operation stage, and the switching condition ⑤ is that the speed loop tracking process of the system has stabilized.

[0063] Furthermore, the desired current signal i controlled by IF in steps S2 and S3 f All are represented as

[0064]

[0065] Let t be the expected value of the current along the q-axis in the dq coordinate system, and t be time.

[0066] Furthermore, in step S3, proportional-integral-resonant closed-loop control is used, specifically implemented as follows: Figure 3 The PIR current controller shown is an example. Figure 3 As shown, the transfer function of the proportional-integral-resonant closed-loop control is...

[0067]

[0068] Where k p k i k rThese are the proportional coefficient, integral coefficient, and resonance coefficient, respectively; ω c ω d Here, ω represents the resonant angular frequency and resonant bandwidth, respectively, and s is the complex frequency in the Laplace transform; the resonant control frequency of the proportional-integral-resonant element in the current closed-loop control is set to ω. This is used to improve the phase tracking effect of AC current and AC voltage, and reduce overcurrent caused by the phase mismatch between the motor's rotating back EMF and the initial voltage of the power inverter circuit during startup; during belt-speed startup, the proportional-integral control parameter k is set. p k i To suppress the amplitude of the inrush current, the resonant control element coefficient k is set. r ω c ω d To reduce phase tracking deviation of the alternating current, the resonant frequency ω of the resonant circuit needs to be updated in real time according to changes in wheel speed. c It is used to improve the dynamic tracking performance of the current controller.

[0069] Furthermore, during step S4, the AC frequency of the motor current changes synchronously with the motor speed and vehicle speed, and the electric angular velocity of the motor is estimated by a sensorless estimation algorithm. Let the resonant frequency and resonant bandwidth of the resonant circuit be respectively:

[0070]

[0071] This is used to reduce the amplitude and phase errors in current tracking, achieving optimal tracking of sinusoidal AC current; among which The amplitude of the fluctuation in the estimated angular velocity;

[0072] According to formulas (2) and (3), the improved transfer function of the quasi-resonant element is obtained as follows:

[0073]

[0074] The sensorless estimation algorithm includes rotor position. and angular velocity The estimation calculation is specifically expressed as follows:

[0075]

[0076]

[0077]

[0078] Where, ψ α ψ β u α u β iα i β Represent the motor flux linkage, voltage, and current in the α-β coordinate system, respectively, R s L s These are the motor stator resistance and inductance, respectively, and LPF is a low-pass filter.

[0079] In addition, such as Figure 2 As shown, according to the topology of the control system, in the belt-speed start control, the main controller can restore the current closed-loop control through the current tracking process and estimate the initial rotor information of the motor (corresponding to step S3). After the rotor estimation stabilizes, the motor speed closed-loop control can be restored through the speed synchronization recovery process (corresponding to step S4). The specific operation process is as follows: First, turn on control switch 1, and obtain the synchronous voltage u of the motor through the zero-desired current tracking process of the dq axis. d u q and current signal i d i q This allows for the estimation of the motor rotor speed and position signals. After the rotor estimation signal stabilizes, simultaneously turn on control switches 2 and 3 to switch into the speed loop and restore normal operation of the dual closed loop.

[0080] Figure 4 The diagram shows the complete waveform and detailed diagram of the motor current during vehicle start-up at speed. Stage S1 represents the motor's current-free state after power loss, while stage S2 represents the initial motor current state when the control system triggers the protection mechanism. The inrush current is suppressed after 0.05 seconds. Details are shown below. Figure 5 As shown; S3 is the resonant tracking stage of the current, and the stable tracking process of the alternating current is as follows. Figure 6 As shown, the current frequency is the same as the motor speed frequency; S4 is the speed tracking stage of starting with speed, indicating the switch from the speed open-loop and current closed-loop IF control to the speed and current dual closed-loop control; S5 is the stable operation stage, where the motor is re-engaged in the vehicle powertrain and the current tends to stabilize.

[0081] The present invention also provides a belt-start control system for distributed wheel-side / hub motors, comprising:

[0082] The wheel-side / hub motor speed-off coasting module is used to set up a protection mechanism that is triggered when the motor is coasting with the wheel-side / hub motor speed-off due to instantaneous overcurrent, overheating or unstable wheel speed sensor signal. The drive circuit is shut down to de-energize the motor, the wheel is dragged by the drive wheel, the motor current is 0, the motor speed signal is unavailable, and the motor is in an electrically runaway state.

[0083] The wheel-side / hub motor speed-start preparation module is used to set the initial expected values ​​of the d-axis and q-axis currents in the main controller's current loop control program to zero, employing a constant current-frequency ratio (IF) control method. As the current command for IF control, it simultaneously acquires the motor speed signal of the drive wheel and takes the average value of the electric angular velocity of the drive wheel as... As the frequency command for the IF control method; setting the current phase angle θ r0 =0, serving as the initial phase for the IF control method; simultaneously, the initial motor speed in the main controller's speed loop control program is set to...

[0084] The wheel-side / hub motor speed-up current tracking module is used to enable the main controller to activate the PWM control signal of the power inverter circuit during the speed-up current tracking phase of the wheel-side / hub motor, thereby implementing a rotation frequency of... The IF control strategy uses proportional-integral-resonant closed-loop control to achieve rapid tracking and impact suppression of the motor's d-axis and q-axis currents, and the command voltage is obtained by observing the motor vector control model. and The power inverter circuit outputs a command voltage to the motor and further generates current.

[0085] The wheel-side / hub motor with speed-up starting speed tracking module is used to obtain the current motor speed and rotor angle through a sensorless estimation algorithm after the rapid current tracking process has stabilized. The estimated motor speed value is used as the feedback value of the speed closed loop, and the estimated rotor angle value is used as the rotation angle of the dq coordinate system. The phase current measurement value is substituted into the dq coordinate transformation to calculate the feedback value of the current closed loop. Then, the control mode is quickly switched from the speed open-loop and current closed-loop IF control to the speed and current dual closed loop to achieve speed tracking.

[0086] The wheel-side / hub motor speed-start and stable operation module is used to re-engage the motor that is already running normally into the vehicle's powertrain. The main controller receives torque distribution signals and speed signals from the vehicle's master controller to implement multi-wheel coordinated control of the vehicle. At the same time, the main controller detects non-destructive faults in the motor drive system, such as instantaneous overcurrent, overheating, or wheel speed sensor signal instability, in real time.

[0087] This invention proposes a method for speed-on restart of a hub motor drive system without the need for voltage and position sensors. The aim is to ensure safe power-on of the motor drive controller during vehicle operation without requiring a restart. This invention addresses the redundant structure of distributed electric vehicle multi-wheel drive systems by utilizing wheel speed sensor signals from redundant wheels to obtain the initial motor speed signal. A proportional-integral-resonant (PIR) controller is employed to achieve stable tracking of AC current and AC voltage, enabling full-speed-range power-on restart. The PIR controller features tracking suppression characteristics against steady-state error at specific frequencies, effectively suppressing motor current surges during the initial power-on startup phase and improving the dynamic tracking performance of the current loop. This allows the hub motor disconnected from the powertrain to reliably and smoothly engage at different speeds. This invention does not rely on additional voltage and speed sensors; it only requires signals from the inherent motor phase current sensors to achieve reliable power-on operation under speed conditions, making it particularly suitable for applications caused by wheel speed sensor failures.

[0088] The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. A belt-driven start control method for distributed wheel-side / hub motors, comprising at least two independent drive units, each drive unit including a wheel-side permanent magnet motor or a hub permanent magnet motor, a wheel speed sensor, a current sensor, a signal acquisition circuit, a main controller, and a power inverter circuit; the wheel speed sensor is coaxially connected to the drive unit or connected via gear meshing; the current sensor is located on the motor three-phase output side of the power inverter circuit; the signal acquisition circuit is electrically connected to both the wheel speed sensor and the current sensor; the main controller is electrically connected to both the signal acquisition circuit and the power inverter circuit; characterized in that, Includes the following steps; S1, Wheel-side / hub motor coasting phase with power loss: During the speed-loss coasting phase of the wheel-side / hub motor, the motor triggers a protection mechanism due to instantaneous overcurrent, overheating, or unstable wheel speed sensor signal. The drive circuit shuts down, causing the motor to lose power. The wheel is then dragged by the drive wheel, and the motor current is 0. The motor speed signal is unavailable, and the motor is in an electrically runaway state. S2, Wheel-side / Hub Motor Speed-Drive Start-up Preparation Stage: In the preparatory stage of the wheel-side / hub motor's belt-speed start-up, a constant current-frequency ratio (IF) control method is adopted, setting the initial expected values ​​of the d-axis and q-axis currents in the main controller's current loop control program to zero. As the current command for IF control, it simultaneously acquires the motor speed signal of the drive wheel and takes the average value of the electric angular velocity of the drive wheel. As the frequency command for the IF control method; setting the current phase angle θ r0 =0, serving as the initial phase for the IF control method; simultaneously, the initial motor speed in the main controller's speed loop control program is set to... S3, Wheel-side / Hub Motor Speed-up Starting Current Tracking Stage: During the on-speed starting current tracking phase of the wheel-side / hub motor, the main controller activates the PWM control signal of the power inverter circuit, implementing a rotation frequency of... The IF control strategy uses proportional-integral-resonant closed-loop control to achieve rapid tracking and impact suppression of the motor's d-axis and q-axis currents, and the command voltage is obtained by observing the motor vector control model. and The power inverter circuit outputs a command voltage to the motor and further generates current. S4, Wheel-side / hub motor speed-tracking start-up phase: After the rapid current tracking process in step S3 stabilizes, the current motor speed and rotor angle are obtained through a sensorless estimation algorithm. The estimated motor speed is used as the feedback value of the speed closed loop, and the estimated rotor angle is used as the rotation angle of the dq coordinate system. The phase current measurement value is substituted into the dq coordinate transformation to calculate the feedback value of the current closed loop. Then, the control mode is quickly switched from the IF control of speed open loop and current closed loop to speed and current dual closed loop to achieve speed tracking. S5, stable operation phase of wheel-side / hub motor with speed start: The motor that is already running normally is put back into the vehicle's powertrain. The main controller receives torque distribution signals and speed signals from the vehicle's master controller and implements multi-wheel coordinated control of the vehicle. At the same time, the main controller detects non-destructive faults such as instantaneous overcurrent, overheating or wheel speed sensor signal instability in the motor drive system in real time. If the fault occurs again, steps S1 to S5 are repeated.

2. The belt-driven start control method for distributed wheel-side / hub motors according to claim 1, characterized in that, The desired current signal i controlled by IF in steps S2 and S3 f All are represented as Let t be the expected value of the current along the q-axis in the dq coordinate system, and t be time.

3. The belt-driven start control method for distributed wheel-side / hub motors according to claim 1, characterized in that, The transfer function of the proportional-integral-resonant closed-loop control described in step S3 is: Where k p k i k r These are the proportional coefficient, integral coefficient, and resonance coefficient, respectively; ω c ω d Here, ω represents the resonant angular frequency and resonant bandwidth, respectively, and s is the complex frequency in the Laplace transform; the resonant control frequency of the proportional-integral-resonant element in the current closed-loop control is set to ω. This is used to improve the phase tracking effect of AC current and AC voltage, and reduce overcurrent caused by the phase mismatch between the motor's rotating back EMF and the initial voltage of the power inverter circuit during startup; during belt-speed startup, the proportional-integral control parameter k is set. p k i To suppress the amplitude of the inrush current, the resonant control element coefficient k is set. r ω c ω d To reduce phase tracking deviation of the alternating current, the resonant frequency ω of the resonant circuit needs to be updated in real time according to changes in wheel speed. c It is used to improve the dynamic tracking performance of the current controller.

4. The belt-driven start control method for distributed wheel-side / hub motors according to claim 3, characterized in that, During step S4, the AC frequency of the motor current changes synchronously with the motor speed and vehicle speed, and the electric angular velocity of the motor is estimated by the sensorless estimation algorithm. Let the resonant frequency and resonant bandwidth of the resonant circuit be respectively... This is used to reduce the amplitude and phase errors in current tracking, achieving optimal tracking of sinusoidal AC current; among which The amplitude of the fluctuation in the estimated angular velocity; According to formulas (2) and (3), the improved transfer function of the quasi-resonant element is obtained as follows:

5. The belt-driven start control method for distributed wheel-side / hub motors according to claim 4, characterized in that, The sensorless estimation algorithm includes rotor position. and angular velocity The estimation calculation is specifically expressed as follows: Where, ψ α ψ β u α u β i α i β Represent the motor flux linkage, voltage, and current in the α-β coordinate system, respectively, R s L s These are the motor stator resistance and inductance, respectively, and LPF is a low-pass filter.

6. A belt-speed start control system for distributed wheel-side / hub motors, used to implement the belt-speed start control method for distributed wheel-side / hub motors as described in any one of claims 1-5, characterized in that, The belt-start control system for distributed wheel-side / hub motors includes: The wheel-side / hub motor speed-off coasting module is used to set up a protection mechanism that is triggered when the motor is subjected to instantaneous overcurrent, overheating or wheel speed sensor signal instability during the wheel-side / hub motor speed-off coasting phase. The drive circuit is shut down to de-energize the motor, and the wheel is dragged by the drive wheel to coast. The wheel-side / hub motor speed-start preparation module is used to set the initial expected values ​​of the d-axis and q-axis currents in the main controller's current loop control program to zero, employing a constant current-frequency ratio (IF) control method. As the current command for IF control, it simultaneously acquires the motor speed signal of the drive wheel and takes the average value of the electric angular velocity of the drive wheel. As the frequency command for the IF control method; setting the current phase angle θ r0 =0, serving as the initial phase for the IF control method; simultaneously, the initial motor speed in the main controller's speed loop control program is set to... The wheel-side / hub motor speed-up starting current tracking module is used to enable the main controller to activate the PWM control signal of the power inverter circuit during the speed-up starting current tracking phase of the wheel-side / hub motor, thereby implementing a rotation frequency of... The IF control strategy uses proportional-integral-resonant closed-loop control to achieve rapid tracking and impact suppression of the motor's d-axis and q-axis currents, and the command voltage is obtained by observing the motor vector control model. and The power inverter circuit outputs a command voltage to the motor and further generates current. The wheel-side / hub motor with speed-up starting speed tracking module is used to obtain the current motor speed and rotor angle through a sensorless estimation algorithm after the rapid current tracking process has stabilized. The estimated motor speed value is used as the feedback value of the speed closed loop, and the estimated rotor angle value is used as the rotation angle of the dq coordinate system. The phase current measurement value is substituted into the dq coordinate transformation to calculate the feedback value of the current closed loop. Then, the control mode is quickly switched from the speed open-loop and current closed-loop IF control to the speed and current dual closed loop to achieve speed tracking. The wheel-side / hub motor speed-start and stable operation module is used to re-engage the motor that is already running normally into the vehicle's powertrain. The main controller receives torque distribution signals and speed signals from the vehicle's master controller to implement multi-wheel coordinated control of the vehicle. At the same time, the main controller detects non-destructive faults in the motor drive system, such as instantaneous overcurrent, overheating, or wheel speed sensor signal instability, in real time.

7. The belt-driven start control system for distributed wheel-side / hub motors according to claim 6, characterized in that, In the wheel-side / hub motor speed-off coasting module, the specific state of the motor is as follows: the motor current is 0, the motor speed signal is unavailable, and the motor is in an electrically runaway state.

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