具有模糊边界层的PMSM改进型滑模观测器设计

Design of Improved Sliding Mode Observer for PMSM with Fuzzy Boundary Layer

针对观测器中存在的固有抖振问题,选用斜率可变的双曲正切函数作为切换函数以削弱切换面抖振,并为此设计了一个模糊调节器,使其能根据系统抖振大小动态调节切换函数的斜率值以改变边界层厚度,很好地平衡了柔滑抖振和稳态误差之间的矛盾。另外,固定的滑模增益容易导致电机低速时抖振大,高速时位置转速估计不精准,在观测器满足李雅普诺夫稳定性的条件下,设计了基于转子角速度自适应调节的滑模增益,利用锁相环技术提取转子位置和速度信息提高了估算精度,削弱了计算噪声。仿真及实验结果表明,改进后的滑模观测器估计精度高、抖振小,在永磁同步电机的宽调速范围内,观测效果依然良好。

Aiming at the inherent buffeting problem in the observer,hyperbolic tangent function with variable slope is selected as the switching function to weaken the chattering of the switching surface,and a fuzzy controller is designed to dynamically adjust the slopes of the switching function according to size of system buffeting for changing the thickness of the boundary layer,which well balances the contradiction between the buffeting and the steady-state error.Furthermore,a fixed sliding mode gain is easy to cause large buffeting at low speed and inaccurate estimation of position and speed at high speed.Under the condition that the observer satisfies Lyapunov stability,the sliding mode gain based on the adaptive adjustment of rotor angular speed is designed,using PLL technology to extract the rotor position and speed information improves the estimation accuracy and weakens the computational noise.The simulation and experimental results show that the improved sliding mode observer has high estimation accuracy and small buffeting,and the observation effect is still good in the wide speed range of the PMSM control system.