MHz-Driven Snubberless Soft-Switching Current-Fed Multiresonant DC-DC Converter

A new multiresonant step-up dc-dc converter is proposed in this article, which is suitable for obtaining a high dc-dc voltage ratio with minimizing the counts of active and passive components. The proposed dc-dc converter features the snubberless zero current soft-switching (ZCS) commutation with megahertz (MHz) high frequency driving of GalliumNitride-High Electron Mobility Transistor (GaN-HEMT)- based two-phase class-E inverters by adopting quasi resonance and dual parallel load resonance; multiresonant circuitry. The circuit configuration and operation principle are described together with the theory of switch-mode transitions and steadystate power transfer. A frequency-domain analysis is provided on the basis of the equivalent circuit, and the design guideline of multiresonant tanks is provided in details. The essential performances of the proposed dc-dc converter are demonstrated by experiment of 1-2 MHz / 120W prototype; ZCS operations are confirmed over the wide range of load variations (40-100%) with maximum efficiency 91.3% at 86.5% load, electromagnetic interference (EMI) noise reduction 29-79% as compared to hard switching, and the voltage ratio 1.5 times higher than the non-multiresonant topology, and less than 1% low-current ripple factor in the dc inductor.