A new method for balancing a three-phase induction motor supplied by a single-phase source

Abstract

A three-phase induction motor (IM) powered by a single-phase supply is working under a very unbalanced condition, necessitating it to be derated to avoid overheating. To improve the performance of single-phase powered IMs, a new circuit scheme is proposed in this paper. The proposed circuit scheme is inspired by the traditional Steinmetz connection which employs a capacitor to connect the motor's third terminal to either of the two terminals of the single-phase source supplying the motor. The proposed scheme uses two sets of static var compensators (SVCs), a parallel combination of a thyristor-controlled reactor and a capacitor, as a phase balancer. By properly choosing the element values of the two SVCs, this new scheme allows the motor to operate under a perfect balanced three-phase voltage condition.