A low cost single-phase to three-phase power converter for low-power motor drive applications

This paper presents an economic single-phase to three-phase converter which provides variable output voltage and soft starting capability by using four high frequency switches (IGBT, MOSFET), four diodes, and a triac. This converter can run a three-phase Induction motor which is much more efficient compared to a single phase motor. In order to have a balanced output voltage in all modes of operation (start-up, speed control, and steady state) two closed loop controllers has been utilized: one for dc link voltage and the other one for inverter output. The proposed scheme with variable output voltage and fixed frequency provides a limited-range speed control of the induction motor. As a result, the new single-phase to three-phase converter brings the controllable output voltage as in a six-switches standard three-phase inverter. The front-end rectifier has the capability of active input current shaping. Analysis and simulation results are presented in the result section to demonstrate these new features.