A Novel 500-kHz LLC-T Resonant Converter with Wide Output Range

Abstract

The LLC resonant converter is attractive for the electric vehicle charging application due to its high efficiency and high power-density. Nevertheless, the efficiency of the conventional LLC converter suffers from the wide switching frequency for the wide output range applications. In this paper, a novel LLC-T resonant converter, an extra auxiliary transformer in parallel with the L-C resonant tank, is proposed to narrow the switching frequency range for the EV charging application. A 500-kHz, 1.35-kW, 400-V/250-450-V prototype is built to verify the merits of the proposed converter and demonstrates 97.82% peak efficiency.