Speed control for sensorless SPMSM via variable structure controller and EMF-based position estimation scheme

This paper presents a sensorless control strategy for the surface-mounted permanent magnet synchronous motors (SPMSMs) with a sliding mode controller (SMC). To extract accurate rotor position from the back electromotive force (EMF) of the SPMSM, a tangent function-based phase-locked loop (PLL) is established. Without extra tuning of parameters, the position estimation scheme manages to provide accurate rotor position under both forward and reverse rotational speed. Compared to conventional sliding mode control approach, the proposed SMC adopts a nonlinear reaching law, which helps the controller to simultaneously achieve faster reaching time and lower chattering level. Effectiveness of the proposed control strategy is verified by simulation results.