Sliding mode observer combined with fundamental PWM excitation for sensorless control of IPMSM drive

This paper proposes a new high-bandwidth speed sensorless field orientated control system for interior permanent magnet synchronous motor drives for wide speed range operation, including standstill. The sliding mode observer is used for joint stator flux and rotor speed estimation at all speeds. At low speeds, the flux vector estimate of the observer is enhanced by the fundamental PWM excitation technique. This sensorless approach features high control bandwidth, immunity to the motor parameter variation and no additional signal or separate test vector injected. Extensive simulation results are shown to verify the effectiveness of the proposed method. By using the enhanced sliding mode observer, the proposed sensorless drive exhibits smooth transition between the low and high speeds operation and high dynamic and steady-state performances over a wide speed range.