Control of Single Phase Induction Motor Using Forced-Commutated Electronic Switches and Free-Wheeling Paths

Abstract

Single phase induction motors show better performance and have less cost if they are controlled using electronic switches instead of mechanical switches. This paper suggests a semiconductor-based method to start the motor and to control the speed and the direction of rotation. This is achieved by feeding the two stator windings of a split-single-phase motor via two forced-commutated solid-state devices. Meanwhile, each winding is shunted by a free-wheeling path that is controlled as well by a forced-commutated solid-state device. Therefore high starting torques and low starting currents are realized. Speed control is easily achieved at higher motor efficiency, compared with the case of controlling the motor using forced-commutated electronic switches without free-wheeling paths. This paper computes detailed performance characteristics of the motor employing the suggested method. For this purpose, the motor is represented in the dqo reference frame. Then, the performance is described by a developed state space mathematical model taking care of the discontinuities introduced by the electronic switches.