Calculated performance of AC motors in a single-phase to three-phase converter application

In this paper the performance of induction motors operating with a single-phase to three-phase converter is analyzed. Usually, the motor is connected in open-delta, one side is fed by the AC supply, and the other side by a PWM waveform; as a result, the motor operates under unbalanced conditions. The effect of this unbalance is evaluated taking into account the percent of voltage unbalance, as defined by NEMA standards; the reduction of the torque; the additional rotor losses, and the overheating of the motor. For evaluation purposes, a programmed PWM technique and a class B, ¾ HP induction motor are used