Sensorless Control of Low Speed PMSM Based on Novel Sliding Mode Observer

This paper presents a novel sliding mode observer (SMO) based on the permanent magnet flux linkage of permanent magnet synchronous motor (PMSM). The stability of the proposed SMO is further proved with the Lyapunov function. As the sliding mode gain required by the proposed SMO to satisfy the stability condition is much smaller than the traditional back-electromotive force based SMO, the proposed SMO effectively weakens chattering and avoids the use of low-pass filter, delivers higher precision of position and speed estimation in low speed. A linear extended state observer (LESO) is incorporated into the quadrature phase locked loop (Q-PLL) to achieve better dynamic performance under large load torque. Finally, the proposed sensorless control strategy is tested in MATLAB/Simulink for its speed tracking capability under low speed. Simulation results validate the feasibility and effectiveness of the proposed sensorless control strategy.