A simple algorithm to control two-phase induction motors using a two-leg VSC

This paper proposes a novel control method for two-phase induction motors using a two-leg voltage-sourced converter (VSC) in high speed applications and field-weakening regions. The proposed Approximate Stator Flux Control (ASFC) method is based on the dynamic model of two-phase induction motors and provides good dynamic behavior of the drive system. The switching strategy of ASFC method is proposed and the speed of the rotating field and the average switching frequency of the VSC are derived. ASFC method controls the speed of the rotating field by adjusting the stator flux modulus. No need to use current transducers and mechanical sensors makes implementation cost of ASFC comparable with that of the conventional scalar control system. Through simulations, the performance of the proposed two-phase ASFC method is evaluated and compared with the scalar control method. In addition, the correctness of the presented theories of ASFC method is validated by dynamic simulations.