A sensorless vector strategy for the PMSM using improved sliding mode observer and fuzzy PI speed controller

To reduce the cost and obtain accurate rotor position of the permanent magnet synchronous motor (PMSM), a sensorless vector strategy for the PMSM using an improved sliding mode observer (SMO) and a fuzzy PI speed controller is proposed. The mathematical model of the PMSM is firstly presented. Then, a sigmoid function is applied to the improved SMO for overcoming chattering, and the observer of back electromotive force instead of the low-pass filter is introduced to the SMO. The stability of the improved SMO is further proved with the Lyapunov function. Additionally, the fuzzy PI speed controller is designed. The simulation is performed based on MATLAB, and the experiment is carried out under the developed test rig based on DSP TMS320F2808. The effectiveness of the proposed strategy is finally verified.