Coupled Inductor-assisted Current-Fed Snubber-less Zero-Current-Soft Switching High Step-Up DC-DC Converter for Fuel Cell Power Interface

摘要

A new zero current soft switching high frequency (HF)-link dc-dc converter for fuel cell (FC) interface is presented in this paper. In a power and energy conversion processing of fuel cells, a dc-dc converter should ensure a high voltage step-up ratio with the low current ripple to avoid damage for the electrodes inside the cells. The newly-proposed dc-dc converter features a low current ripple with magnetically coupled inductors which have 180° phase difference of interleaved manner and surge-less ZCS operation while minimizing a number of passive components and stray inductance of the high-frequency planar-transformer (HFPT). The operation principle is introduced with the analysis of coupled inductors currents, which reveals that the coupled inductors have the effect of reducing the current ripple of input inductors. The steady-state performance of the proposed dc-dc converter is described in a time-domain analysis, after which the circuit operation is demonstrated with a mega hertz (MHz) driving of HF inverter. The actual performances are evaluated by experiment based on a 60W-l MHz prototype featuring a 600 V Gallium Nitride HeterojunctionField-Effect-Transistor (GaN-HFET) suitable for MHz driving. Then, the feasibility of the proposed dc-dc converter is verified from the viewpoints of current ripple, efficiency and voltage ratio.