A new high-bandwidth sensorless direct torque controlled IPM synchronous machine drive using a hybrid sliding mode observer

This paper proposes a new high-bandwidth speed sensorless direct torque control of 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 sliding mode observer is enhanced by the fundamental PWM excitation technique, which is used to correct the direction of flux vector estimate of the observer. Compared with the hybrid observer with HF injection, the proposed observer features higher bandwidth, lower torque and flux ripples and no additional signal or separate test vector injected. Extensive simulation results are shown to verify the effectiveness of the proposed method, which exhibits smooth transition between hybrid and pure sliding mode observer structures and high dynamic and steady-state performances over a wide speed range.