A Novel Multimode AC-DC LLC Resonant Converter for Wide Output Voltage Range Applications

In this article, a novel multimode ac-dc LLC converter for ultra-wide output voltage range electric vehicle (EV) applications is presented. By integrating the totem-pole Boost power factor correction (PFC) converter with Full bridge (FB) LLC resonant converter and using small-capacity bus capacitor, the proposed converter can operate in single-stage, quasisingle-stage, or two-stage mode, effectively extending the output voltage range. Moreover, a unified control scheme for different modes is presented to achieve output regulation and power factor correction simultaneously. The smooth transition between different operating modes can be achieved by an optimized control strategy. The detailed operational principle and design considerations of the proposed converter are analyzed and discussed. Finally, an experimental prototype rated at 100∼420 V/3.3 A under 180∼260 V_ac input is built-up to verify the theoretical analysis. Experimental results show that good efficiency (>95.0%) is achieved over the full charging range and the peak efficiency reaches 96.5%.