永磁同步电机无传感器控制的软开关滑模观测器

Soft Switching Sliding Mode Observer for PMSM Sensorless Control

针对滑模观测器估计中存在的抖振问题,采用边界层可变的正弦型饱和函数替代传统开关函数,提出了一种用于永磁同步电机无传感器控制的软开关滑模观测器。为了确定不同饱和函数的收敛速度,定义等效收敛区间,通过正弦型饱和函数边界层内的滑模状态表达式推导其等效收敛时间,并与现有初等、终端滑模型和双曲正切型饱和函数进行了对比。为扩大滑模观测器的速度适用范围,确定了开关增益的转速自适应律。利用锁相环方法提取转子位置与速度信息,解决由滤波器引起的相位误差。通过仿真分别分析了饱和函数类型和开关增益、等效收敛系数及边界层厚度等系数对估计精度与收敛时间的影响,验证了正弦型饱和函数的有效性。实验结果表明,正弦型软开关滑模观测器能够准确地观测出转子速度和位置,并很好地消除了估计结果的抖振。

In order to alleviate the chattering problem in conventional sliding mode observer(SMO), this paper proposes a soft switching(SS) SMO for sensorless control of permanent magnet synchronous motor(PMSM), in which the traditional switching function is replaced with a boundary-layer-flexible sinusoidal saturation function. Equivalent convergence interval is defined so as to obtain velocities of convergence of different saturation functions, based on which the equivalent convergence time of the sinusoidal saturation function is deduced from sliding mode state between the boundary layers, and compared with existing elementary, terminal sliding-mode and hyperbolic tangent saturation functions. Adaptive law of switching gain is regulated with the rotor speed to expend the functional range of SMO. Phase locked loop method is adopted to extract the rotor speed and position for compensating the phase lag resulted from filter. The effects of saturation function types, switching gain, equivalent convergence coefficient and boundary layer thickness on estimation accuracy and convergence time are analyzed according to simulation results. Experimental results show the SS-SMO is effective for speed and rotor position extraction and confirm its ability of chattering elimination.