Research on the effect of input current by switching method in three-phase 4-wired to single-phase 3-wired matrix converter

Abstract

– A single-phase 3-wired matrix converter connecting three-phase 4-wired micro-grid is used instead of transformers to improve the power quality on the Micro-grid. The switching harmonic analysis of the inverter circuit has been studied by former researchers. However, in MC systems, the harmonics of input current caused by switching operation has not been analyzed. MC is generally used for motor drive and the output currents of MC are smoothed by inner inductor in the motor.However, the series inductor used in the output filter is relatively small, so that the voltage drops due to the filter has small impact on the output current harmonics, which becomes large compared to the fundamental component and it influences the phase of the input fundamental current. In this paper, we formulate that the harmonics in output voltage finally effect the input current phase error of single-phase MC. The harmonics of input current caused by switching is calculated and confirmed by simulation.