Unity power factor operation for three-phase induction motor

This paper describes the feasibility of unity power factor operation for three-phase induction motor subjected to variable loads. The basic idea is to use a shunt active power filter to provide such operation. The operation principle is introduced. The two-loop control strategy is analyzed. Simulation results show that, under all loading conditions, unity power factor is achieved automatically. Furthermore, the supply current can be kept sinusoidal. A microcontroller-based system has been tested in the lab to confirm the analysis. The experimental results show that the strategy to improve power factor of the motor is feasible.