A current fed multi-resonant converter with extended voltage regulation range

A previously proposed current fed multi-resonant converter (CFMRC) has the merits of low input current ripple, high step-up capability and high efficiency. However, in order to ensure zero-current switching (ZCS) of its secondary rectifying diodes, the switching frequency range is limited hence the voltage regulation range is limited. In this paper, the switching frequency range is broadened for the purpose of extending the voltage regulation range of the CFMRC. Although ZCS of the rectifying diodes are lost when pushing the switching frequency much higher than the resonant frequency, SiC diodes are applied to the secondary rectifier to eliminate the reverse recovery issue and the efficiency of the converter is not affected much. The merits of the proposed converter is verified by a 150 W prototype operating from 255 kHz to 355 kHz, the voltage gain achieves 22 at 355 kHz switching frequency and the peak efficiency is as high as 96%.