基于自抗扰滑模控制的开关磁阻电机转矩分配控制策略

Torque Sharing Function Control Strategy for Switched Reluctance Motor Based on Active Disturbance Rejection Sliding Mode Control

针对开关磁阻电机运行时存在的转矩波动大与外部干扰下电机运行不稳定等问题,该文提出了一种基于自抗扰滑模控制的开关磁阻电机转矩分配控制策略。由于传统滑模控制中趋近律采用的符号函数引起系统振荡频率高,造成被控对象抖振大,该文采用新型滑模趋近律,用平滑函数代替符号函数,并引入状态变量,同时提升了响应速度并降低抖振;此外,为了解决开关磁阻电机外部干扰对电机运行带来的稳定性问题,该文设计了一种自抗扰扩张状态观测器,这种观测器可以实现对负载扰动的实时观测,将观测值作为滑模速度控制器的前馈补偿,减小电机固有参数不确定对控制系统的影响。最后,通过仿真和实验验证了所提出的方案能够有效地改进控制系统在不同工况下的动态性能。

The research of new energy electric vehicles is currently a hot topic.Switched reluctance motors(SRM)are applied in electric vehicles due to their simple structure,robust fault tolerance,and ease of control.Among them,motor torque ripple and system response speed are critical indicators to measure the performance of motor drive systems.Sliding mode control is a nonlinear algorithm with the advantages of fast response speed and strong robustness,including sliding mode approach law and sliding mode surface.The sign function used in the traditional exponential approach law can cause system oscillation and large chattering in the control system.The smooth function is used instead of the sign function,and the system state variable is introduced to improve control flexibility.At the same time,an improved integral sliding surface is proposed to improve the convergence of the traditional integral sliding surface.Because of the nonlinearity,the motor’s load torque and inherent parameters significantly affect the operation of the motor under variable speed and load conditions.Therefore,the active disturbance rejection extended state observer(ADRESO)is used as a feedforward compensation for the sliding mode speed controller to adjust the uncertain parameters and load torque of the motor.The design of the ADRESO does not require an accurate mathematical model of the motor,and it can ensure the stability of the system under complex operating conditions and has strong robustness.Experimental results of an actual switched reluctance motor show that under steady-state operating conditions,when the motor load is 0.5 N•m and the set speeds are 500 r/min and 1000 r/min,the proposed active disturbance rejection sliding mode control(ADRSMC)results in smaller motor pulsation.Under variable speed conditions,when the load torque is 0.2 N•m,the starting time of the system using PI control and traditional sliding mode control is 0.7 s and 0.25 s,and the variable speed response time is 0.65 s and 0.28 s.The starting time of the system with the proposed ADRSMC is 0.07 s,and the variable speed response time is 0.1 s.When the load torque is 0.5 N•m,the starting time of the system using PI control and traditional sliding mode control is 0.95 s and 0.3 s,and the variable speed response time is 0.73 s and 0.5 s.The starting time of the system with the proposed ADRSMC is 0.12 s,and the variable speed response time is 0.13 s.The proposed method reduces motor speed fluctuations under stable operation.Under variable load conditions,when the set speed is 500 r/min,the time for the system to return to the original state with PI control and traditional sliding mode control is 0.38 s and 0.12 s.The response time of the system with the proposed ADRSMC is 0.03 s.When the set speed is 1000 r/min,the time for the system to return to the original state using PI control and traditional sliding mode control is 0.43 s and 0.33 s.The system’s response time with the proposed ADRSMC is 0.08 s,indicating that the proposed ADRSMC can approach the original speed in a relatively short period.It can be concluded that the proposed control strategy can effectively reduce the torque ripple of the motor,improve the response time of the system,and enhance the stability of the speed.