Sensorless position control for four-switch three-phase synchronous reluctance motor drives

This paper proposes a novel sensorless technique applied to position control for four-switch three-phase synchronous reluctance motor drives as opposed to conventional methods which use six switches. According to the defined three-phase current-slope vectors of the synchronous reluctance motor with four designated active-voltage vectors generated by a four-switch three-phase inverter, the proposed technique can extract rotor position from the components of difference current-slope vectors. Cost down of synchronous reluctance motor driver is achieved by reducing the number of power switches, reducing the algorithm coding effort, and eliminating the encoder or the resolver. In addition, the proposed technique achieves position control with satisfactory performance. Moreover, no additional hardware circuits and no switching strategy change are required for existing drive systems. The feasibility and effectiveness of the proposed method are demonstrated by simulation results.