Speed Control for PMSM Drive System Based on Sliding Mode Observer with Phase-Locked Loop and Variable Proportional Desaturation PI Regulator

The sensorless control methods in terms of the traditional sliding mode observer (SMO) will usually produce a large number of high frequency harmonics and integral saturation problems, which will lead to a large deviation of the estimated speed of the drive system and poor dynamic performance. Hence, a novel variable proportional desaturation proportional integral (VPDPI) speed regulator design method based on SMO with phase-locked loop (PLL) is proposed in this paper. Firstly, the PLL-SMO speed sensorless observation method is designed by self-closed-loop phase angle prediction, which greatly weakens the high frequency chattering caused by traditional SMO observation under PMSM vector control. Unfortunately, the integral saturation would be intensified due to the introduction of the PLL. To achieve it, a novel VPDPI speed regulator is further designed by combining the self-judging multi-mode switching mode with the concept of threshold segmentation, which ensures that the saturation problem in the PLL and the whole drive system can be totally eliminated. The experimental results indicate that the proposed sensorless drive system based on VPDPI regulator can accurately track the actual speed. Meanwhile, compared with the traditional PI control effect, it has better speed response performance.