A multi-level buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications

Abstract

A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multilevel diode rectifier and a multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier has a few other features such as reliable operation and high voltage operation capability. This paper addresses a number of system design considerations such as switching pattern, input power quality and the effects of discrepancies of transformer leakage inductances on the system performance. Experimental results on a 5 kVA/208 V four-level prototype are also included.