An Integrated Boost-LC-Resonant-Flyback Multimode Converter for Battery Charger Applications

An integrated boost-LC-resonant-flyback multimode converter with a wide voltage gain is proposed in this article. With three different pulsewidth modulation strategies, the proposed converter can realize three modes including high-, medium- and low-voltage-gain (LG), by multiplexing inductors and power switches. In the high-voltage-gain mode, it has better load characteristics than the conventional LLC converter through an extra energy storage stage. In the medium-voltage-gain mode, the working condition is similar to that of the conventional LLC converter, but the issues of current reflow and circulation can be addressed than reducing the conduction loss. In the LG mode, the proposed converter works as a flyback converter, and it has a higher conversion efficiency and simpler operation state than the conventional LLC converter. Additionally, all power switches can realize zero-current switching over a wide load range. The operating principle, voltage gain, design methodology, and control scheme are fully presented in this article. Finally, a laboratory prototype with 110 V input voltage, 0-5 A output current, and 24-165 V output voltage was conducted and verified the proposed solution.