基于新型趋近律的永磁同步电机滑模速度控制

系统惯性和切换开关的时间滞后造成了滑模控制系统的抖振问题。为了解决该问题,提高永磁同步电机调速系统的动态品质,设计了新型趋近律。趋近律引入了系统状态变量绝对值的反正切函数,减小接近滑模面时的速度。用变边界层饱和函数代替常规的符号函数,使滑模面附近沿滑模面的运动更平滑。负载转矩是滑模速度控制器中的一个扰动项,采用以转矩和转速为观测对象的扩展滑模观测器对负载转矩进行观测,将观测值引进滑模速度控制器进行前馈补偿,进一步提高控制系统的抗扰性。仿真结果表明,改进后的趋近律在减小滑模面趋近时间的同时,有效地削弱了系统的抖振。负载转矩观测器在负载阶跃变化时能够进行准确的跟踪。相较于传统的指数趋近律滑模控制,基于新型趋近律的滑模控制响应速度快、无超调、抗扰性强,能够实现永磁同步电机良好的调速动态品质。

Sliding Mode Speed Control of Permanent Magnet Synchronous Motor Based on New Reaching Law

The system inertia and the time lag of the switching switch cause the buffeting problem of the sliding mode control system. In order to solve this problem and improve the dynamic quality of the permanent magnet synchronous motor speed control system,a new reaching law was designed. The reaching law introduced the arc tangent function of the absolute value of the system state variable,reducing the speed near the sliding surface. The variable boundary layer saturation function was used instead of the conventional symbol function to make the movement near the sliding surface and along the sliding surface smoother. The load torque was a disturbance item in the sliding mode speed controller. The extended sliding mode observer with the torque and rotation speed as the observation object was used to observe the load torque,and the observation value was introduced into the sliding mode speed controller for feed-forward compensation to further improve the control system’s immunity. The simulation results show that the improved reach law can effectively reduce the chattering of the system while reducing the approach time of the sliding mode surface. The load torque observer can track accurately when the load step changes. Compared to the traditional exponential reaching law sliding mode control,the sliding mode control based on the new reaching law has fast response speed,no overshoot and strong anti-disturbance performance,which can realize the good dynamic quality of speed regulation of permanent magnet synchronous motor.