Closed-loop Torque Control for Permanent Magnet Synchronous Motor by Super-Twisting Algorithm Based Sliding-Mode Observer Considering Demagnetization

This paper presents a precise torque closed-loop control method by super-twisting algorithm based sliding mode observer (STA-SMO). A unified mathematical model of permanent magnet synchronous motor (PMSM) is first described. Then, a STA-SMO is designed to observe the PM flux linkage and to estimate the torque precisely. In particular, the STASMO eliminates the chattering of sliding mode successfully. Stability analysis of STA-SMO is also given in detail. Finally, the simulations results demonstrate the accuracy, validity of the proposed method.