Performance of a series-parallel resonant DC-DC converter module for high current low voltage applications

Recent research into power electronic converters has proposed the use of resonant switching, or soft switching strategies to reduce semiconductor losses under high frequency switching conditions, or to reduce EMI caused by the severe dv/dt and di/dt transitions that are characteristic of hard switched converters. This paper reports on the development of a 630 W resonant DC-DC converter module which provides a 70 A, 9 VDC output from a widely varying high voltage 3-phase AC input supply. The final design achieved better than 85% efficient conversion overall, with the major remaining losses being unavoidable semiconductor losses. The paper includes discussion on both theoretical and practical aspects of resonant converter design.