Three-Phase to Single-Phase Power-Conversion System

A power-conversion system for converting three-phase power into single-phase power is proposed in this paper. The proposed three-phase to single-phase (3φ/1φ) power-conversion system comprises a power converter, a zero-sequence transformer set, and a filter capacitor. The output currents of the power converter are divided into two parts. One is a set of positive-sequence sinusoidal currents, whose phases are in phase with the voltages of the three-phase power source. The positive-sequence sinusoidal currents are employed to absorb a real power from the three-phase power source. In addition, the power converter can perform the functions of three-phase balance, low harmonic distortion, and unity power factor when the single-phase load is used. The other is a set of zero-sequence currents, which will pass through the zero-sequence transformer set and build a single-phase voltage with high power quality for the single-phase load. Since the proposed 3φ/1φ power-conversion system contains only one power converter, it has the advantages of simplifying both the power circuit and control circuit. A prototype is developed and tested to demonstrate the performance of the proposed 3φ/1φ power-conversion system. The experimental results show that the proposed system can achieve the expected performance.