Three-phase AC/DC converter with high power factor

The paper presents a three-phase AC/DC converter to achieve power-factor correction, harmonics elimination, DC-bus-voltage regulation and neutral-point-voltage compensation. The proposed converter can achieve bidirectional power-flow capability. Therefore the converter can be applied for active power-filter operation. Two legs are adopted in the proposed converter to achieve three-level pulse-width modulation (PWM) and control the line currents to be sinusoidal waves in phase with supply voltages. Three control loops, DC-link-voltage control, neutral-point-voltage compensation and line current control, were used in the control scheme to achieve DC-bus-voltage regulation, to balance neutral-point voltage and to draw the sinusoidal line currents. The mathematical model of the converter was derived and the control scheme is provided. The effectiveness of the proposed control scheme is verified through computer simulation and experiments.