Buck-Boost Common Ground Bridgeless PFC (CGBPFC) Rectifies With Positive/Negative Output

This article proposes new common ground bridgeless power factor correction rectifiers suitable for use in any application which requires a positive or negative dc power supply. The main advantage of the proposed rectifiers, compared to previous works, is the provision of the common ground between input and output, which eliminates electromagnetic interference (EMI) associated with high rates of change of voltage and consequently reduces the need for EMI common mode filtering. The converter also provides step-down and step-up operation, and facilitates positive or negative output voltages with a low number of semiconductor devices operating simultaneously. High power factor, acceptable grid-side current quality, and high efficiency are also achieved. Two variants are presented, referred to as type-I and type-II, which offer common ground positive and negative dc voltages, respectively. Closed-loop control of the converters is provided by a dead-beat current controller in the inner loop. Experimental results are presented for a 500-W prototype, operating from 220 and 110 Vrms input to \pm48 and \pm200 Vdc output. The experimental results demonstrate the capability for step-down and step-up ac-to-dc power conversion with a peak efficiency of 96.8% and 96.6% in the positive and the negative outputs, respectively.