A single-phase four-switch rectifier with significantly reduced capacitance

A single-phase four-switch rectifier with considerably reduced capacitance is investigated in this paper. The rectifier consists of one conventional rectification leg and one neutral leg linked with two capacitors that split the dc bus. The ripple energy in the rectifier is diverted into the lower split capacitor so that the voltage across the upper split capacitor, designed to be the dc output voltage, has very small ripples. The voltage across the lower capacitor is designed to have large ripples on purpose so that the total capacitance needed is significantly reduced and highly reliable film capacitors, instead of electrolytic capacitors, can be used. At the same time, the rectification leg is controlled independently from the neutral leg to regulate the input current to achieve unity power factor and also to maintain the dc-bus voltage. Experimental results are presented to validate the performance of the proposed strategy