Adaptive Resonant Energy Realization in FB-ZCS DC-DC Converter Using Dual-Capacitor Circuit

This paper presents a current-fed full-bridge zero current-switching (FB-ZCS) dc-dc converter with adaptive resonant energy, realized using dual-capacitor resonant circuit. In existing FB-ZCS converters, transformer leakage inductance and a resonant capacitor form the L-C resonant circuit to achieve smooth current commutation and soft-switching. 

Two types of resonant capacitor configurations are proposed in literature: shunt-connected across the transformer-secondary and series connected with the transformer-primary. Shunt-connected capacitor has the drawbacks of constant resonant energy and large duty-cycle loss. While series-connected capacitor realizes adaptive resonant energy and reduces duty-cycle loss, it suffers from increased peak-voltage stress for primary-side components and insufficient resonant capacitor voltage at light-loads. 

This paper presents a dual-capacitor resonant circuit to realize adaptive resonant energy and address the aforementioned limitations. Operation of proposed converter is explained and validated through simulation.

Index Terms— Current-fed, dc-dc converter, high-frequency transformer, leakage inductance, dual-capacitor resonant circuit, zero-current switching.