A new direct phase converter to power three phase induction motor from a single phase supply

In this paper, a new approach to directly convert the available single phase power to three phase power suitable for powering an induction motor load is proposed. The proposed phase converter employs four bi-directional switches which define balanced three phase voltages across the motor terminals. Voltage and frequency at the converter output is controllable to acheive variable speed operation of the motor load. The proposed approach does not employ any reactive components and hence is robust and is small in size and weight. A control strategy is proposed to maximize the gain between the output and the input terminals of the converter and also to facilitate the on-off operation of the bi-directional switch for inductive load currents. A thorough analysis of the proposed converter is presented for various load power factors along with simulations. Finally, selected results are verified experimentally on a laboratory prototype converter fed induction motor drive from a single phase supply