Position sensorless control of PMSM based on a novel sliding mode observer over wide speed range

A position sensorless control scheme of permanent magnet synchronous machines (PMSM) without saliency is proposed. The rotor position angle of PMSM is estimated by a novel sliding mode observer over a wide speed range including nux-weakening region. A feedback of the equivalent control is applied in the sliding mode observer. Compared to conventional sliding mode observers (SMO), the proposed approach features the flexibility to design the sliding mode observer with broad operating range. By properly selecting equivalent control feedback gains, the estimation error of rotor position angle can be reduced in the low-speed range and fast convergence guaranteed in the high-speed range. Computer simulation and experimental results are presented to verify the proposed sensorless control algorithm.