The modular-combined three-phase PFC converter based on improved full-bridge structure

Abstract

A phase modular-combined three-phase single-stage power factor correction (PFC) converter based on improved full-bridge structure is proposed in this paper. To reduce the voltage spike existing across the bridge arms and limit the inrush current through the clamp switch, an improved active- clamp circuit is proposed in single-phase full-bridge PFC module. With the control strategy in this paper, soft-switching characteristics can be achieved for all the power switches. On these basis, a phase modular-combined three-phase single-stage PFC converter is derived from three combined single-phase single-stage full-bridge PFC modules. The topology and the operating mechanism of this converter is explained in detail. A control strategy including a shared voltage loop and three independent current loops is used to realize three phase power automatic balance. Besides, the output voltage ripples are analyzed to verify the dominant ripple at two times line frequency (100Hz) ripple is eliminated. Finally, a 1.8kW prototype is built to validate the theoretical analysis.