Novel multi-element resonant converters for front-end dc/dc converters

This paper proposes novel multi-element resonant converters for front-end dc/dc converters. The superior performance of the proposed resonant converters is to provide inherent current protection and very low circulating energy. With the optimized design, the proposed resonant converters can operate under short output circuit. Based on the third order harmonic injection, the circulating energy of the resonant tank can be reduced and lower than other conventional resonant converters, such as LLC resonant converters. Zero-voltage-switching (ZVS) and zero-current-switching (ZCS) can be achieved for primary side and secondary side devices respectively. Furthermore, high voltage gain can be designed for holdup time operation. The hold up time capacitors can be reduced more than 50% compared with conventional circuits. Hence, cost and volume can be saved significantly. Finally, a 1 kW, 1 MHz prototype is built to demonstrate the advantages of the proposed resonant converters. 86 W/in³ power density and 95.5% efficiency at full load are achieved.