Sensorless Control of Permanent Magnet Synchronous Motor Based on the Improved Sliding Mode Observer

Sliding mode observer (SMO) which has a strong robustness is used in the sensorless control system of permanent magnet synchronous motor (PMSM). The method is usually used to estimate the rotor position although it has the chattering problem. According to the causes of the chattering in traditional SMO, the method of improved sliding mode observer (ISMO) is proposed in this paper. Sign function is replaced by the saturation function to suppress the chattering problem, and the speed of PMSM is estimate when combined with field oriented control (FOC) method. A hardware platform of 2.7 kW, 10 000 r/min PMSM is built to verify the control effectiveness of ISMO. Simulation analysis and experimental result show that ISMO can estimate the rotor speed accuracy and reduce the chatting at the same time.