LLC converter combined with switched capacitor for high voltage applications

This paper presents a new LLC converter combined with switched capacitor for high voltage applications. In the proposed converter, the flying capacitor of the switched capacitor is divided into two parts, and they are used as resonance capacitors of an LLC converter. The proposed method reduces the switch voltage stress to a half of the input voltage, and the current in switches are a half of that in transformer. In addition, by increasing the number of switches and capacitors to connect, the proposed converter can be adapted for higher input voltage. The principle of operation and the characteristics of the proposed converter circuit are analyzed and verified on a 400 V input 24V/5A output experimental prototype, of which efficiency is 93.1% at rating condition.