MagCap DC-DC Converter Utilizing GaN Devices: Design Consideration and Quasi-Resonant Operation

Abstract

A MagCap DC-DC converter using GaN semiconductor devices is presented to improve the efficiency and modularity of the vehicular power system. While the topology is as simple as the flyback converter, all the semiconductor switches turn ON and OFF with soft switching. A design guideline to transformer and capacitor is suggested considering the conduction loss and voltage stress of the switches. A quasi-resonant (QR) operation for low output-power condition is also explained. The switches turn ON at the valley of the drain-source waveform to secure soft switching and maximize the efficiency. A 180-W prototype hardware was populated on 63 mm x 31 mm printed circuit board using 200-V GaN FET devices. Peak efficiency was 97.1% at 155-W output power and 1.2-MHz switching frequency. Another prototype was built for the QR operation and demonstrated 91.6% peak efficiency by maintaining the soft switching and avoiding excessive switching frequency.