Novel high frequency power conversion topologies employing soft switching methods

Abstract

In this dissertation, novel soft switching converter topologies for high frequency DC/DC, AC/AC(constant frequency), DC/AC(AC/DC) and AC/AC power conversion are proposed. a new family of soft switching DC/DC converters and two kinds of new soft switching DC/AC(AC/DC) converters are presented to improve the performances of the previously reported soft switching converters while a new family of soft switching AC choppers (constant frequency AC/AC converters) and a new soft switching AC/AC matrix converter are presented as the first soft switching approaches of the AC chopper and AC/AC matrix converter areas. A new resonant switch and a new family of zero current and zero voltage mixed mode switching quasi-resonant converters(QRC``s), named as single cycle reaonant converters(SCRC``s), are proposed to improve the performance of the conventional QRC``s and extend their applications to AC choppers. The proposed SCRC``s which include two active switches operated with zero current switching(ZCS) and zero voltage switching(ZVS), respectively, have distinctive advantages over the ZCS-QRC``s including very simple operation and easiness in control and analysis, and overcome the limited load range characteristics of the contentional ZCS-QRC``s. Furthermore the SCRC``s can be applied even for high frequency AC choppers by replacing unidirectional switches with bidirectional ones. Steady state operation and characteristics of the buck type SCRC``s are analyzed and compared with those of the buck type full wave QRC. To verify the operational principle and characteristics, experimental results at 200KHz, 1KW level are also presented. For the DC/AC(AC/DC) converters, two kinds of new soft switching inverters are newly proposed to overcome the well known problems of the soft switching resonant DC-link inverters particularly as high device voltage stress and subharmonics, one is three phase resonant pole inverter(RPI) for low power applications and the other is a soft switchin...