High-Efficiency Resonant DC-DC Converter With Low Input Current Ripple for DC Power Distribution Systems

A novel resonant dc-dc converter with high efficiency and low input current ripple is presented. Without adding any components, the proposed converter significantly improves the efficiency of the conventional half-bridge converter that has input current ripple reduction. By using two input capacitors and two leakage inductances of the conventional converter as resonant elements, a new high-efficiency resonant converter with a double LLC resonant tank is achieved. Consequently, the proposed converter reduces switching losses by the soft-switching operation of all primary switches and secondary diodes in a wide input voltage range. Moreover, it can improve conduction losses by reducing the voltage stress on the secondary diodes. In addition, the output filter inductor is removed, and the ripple and undesired harmonic components caused by the pulsating input current can be significantly reduced without using a large input filter. The operating principle is analyzed, and the experimental results of a prototype verify the feasibility of the proposed converter.