Speed sensorless PMSM motor drive system based on four-switch three-phase converter

This paper proposes a speed sensorless control for PMSM motor drive system. The sensorless strategy is based on back-emf estimation of the motor, suited for applications at high speed. The drive system uses a four-switches three-phase inverter. This topology is attractive specially in fault conditions in one leg of the conventional three-phase converter. The speed sensorless vector control based on the proposed converter provides a motor drive system with reduction of cost and volume. Relevant characteristics of the converter is presented, such as: voltage capability, capacitor currents, PWM modulation. Details of the vector control implemented is addressed. Simulation results are shown and validates the proposed system. The proposed method are under implementation in an industrial converter.