Research On Speed Synchronization Control Method For Electric Vehicle With Front- And Rear-wheel-driven Srms

With the increase of environmental pollution and the serious of energy depletion,electric vehicles have become one of the important ways to alleviate such problems.Due to the advantages of simple structure,low cost,high reliability and strong fault tolerance,Switched Reluctance Motor(SRM)is widely concerned in the field of electric vehicles.Moreover,dual motors for front-rear-axle is suitable for electric vehicle,because of flexible control,stable system and high power.Then,the issue of asynchronous speed for dual motors will cause unstable operation of the system.According to the issue of speed synchronization for dual motors in electric vehicle,it is studies in terms of control structure,control algorithm and fault tolerance performance in this thesis.The main contents of as follows:Regarding to the problem of dual SRMs given signal delay in traditional virtualspindle-based speed synchronization control method,speed synchronization control of dual SRMs with virtual-spindle-based disturbance observation and feedforward compensation is proposed.Firstly,according to the motor mechanical motion equation and disturbance observation modern control theory,the disturbance observer is designed to observe the disturbance,and the time-varying control factor is introduced in disturbance observer.The virtual speed command is calculated through the disturbance observer and motor parameters.Then,the virtual rotational speed command replaces the reference speed as the input signal in the motor controller.In order to improve the dynamic response performance of dual SRMs,the compensation formula is obtained by observed disturbances,actual speed and reference speed to compensate virtual speed command.In order to reduce the speed synchronization error of the dual motors during the deceleration state,the three closed-loop controllers of speed,turn-off angle and current are designed.In the controllers,the speed loop is inner loop,and the turn-off angle and current ring are outer loop to realize deceleration braking control of dual motors.Simulation and experiments verify the effectiveness of the proposed method.In order to improve the dynamic performance and robustness of the traditional cross-coupled-based speed synchronization control,speed synchronization control of dual SRMs with cross-coupling-based sliding mode control is proposed in this thesis.Sliding mode controller of single SRM is designed to improve the dynamic response of the motor,and sliding mode synchronization controller is designed to reduce the speed synchronization error.In the sliding mode controller of single SRM,the sliding mode surface is designed based on the speed tracking error and state variables.In order to improve the smoothness of the sliding mode control,sgn(s)is replaced by sigmoid(s)in the sliding mode reaching law.The time-varying coefficient of the sliding mode surface and the coupling function of dual SRMs are introduced into sigmoid(s)to reduce sliding mode control chattering.In order to reduce the impact of observed load disturbances for sliding mode control,the system change caused by load disturbance is mapped to the change of sliding mode surface,and the observed value of load disturbance is introduced into the sliding mode controller.Also,the stability of the sliding mode controller is proved by using the Lyapunov function.In the sliding mode synchronization controller,the sliding mode surface is designed based on the speed synchronization error.Then,the compensation factor is introduced into the sliding mode approach law to reduce chattering.In order to reduce the impact of different parameters for dual SRMs,the difference in viscous friction coefficient is ignored and load disturbance observations are introduced.Finally,simulations and experiments verify the effectiveness in terms of dynamic performance and rotational speed synchronization performance.Combining the advantages of virtual-spindle-based and cross-coupling-based speed synchronization control,an anti-disturbance speed synchronization control method based on extended state observer is proposed.On this basis,considering the current sensor power-down,a fault-tolerant speed synchronization control method is given.Speed Synchronization of disturbance rejection is proposed based on the virtual spindle,cross coupling structure and sliding mode control methods.According to observation speed and virtual speed command,pulse width modulation(PWM)signal is generated.The speed is predicted by the speed slope and control cycle.Then,the switching signal is obtained based on the predicted speed of faulty motor and actual speed of another motor.Speed synchronization control of fault-tolerance based on variable PWM is proposed to reduce the impact of current sensor with power-down fault on the drive system based on PWM signal and switching signal.Simulation and experiments verify the effectiveness of the anti-disturbance method and the variable PWM fault-tolerant speed synchronization control method.