基于改进滑模观测器的BLDCM无传感器控制

Sensorless Control of BLDCM Based on Improved Sliding Mode Observer

传统滑模观测器用于无刷直流电机(BLDCM)反电动势观测时,由于系统抖振过大需外加低通滤波器,但滤波器造成的相位延迟无法准确补偿,导致换相不准确。提出将sigmoid函数应用于滑模观测器,利用其光滑连续的特点来减小抖振,并根据Lyapunov定理推导出一种可变滑模增益进一步削弱了系统抖振,获得了可直接判断出换相信号的线反电动势观测值。仿真和实验结果表明:改进滑模观测器在400 r/min和3000 r/min下线反电动势观测误差峰值分别降低了70%和54.8%,获得了更加准确的换相信号,提高了无刷直流电机无位置控制系统的性能。

When the traditional sliding mode observer was used to observe the line back electromotive force(line back-EMF)of brushless dc motor(BLDCM),a low-pass filter was required because of the excessive chattering of the system.However,the phase delay caused by the filter could not be accurately compensated,resulting in inaccurate commutation.This paper proposed to apply the sigmoid function to the sliding mode observer,and used its smooth and continuous characteristics to reduce chattering.At the same time,a variable sliding mode gain was deduced to further weaken the chattering of the system based on the Lyapunov theorem.Through these measures,the line back-EMF observations observed could directly determine the commutation signal.The simulation and experimental results showed that the improved sliding mode observer reduced the peak value of line back-EMF observation errors at 400 r/min and 3000 r/min by 70%and 54.8%respectively,obtained more accurate commutation signals,and improved the brushless dc motor positionless control system performance.