Design and Implementation of Cascoded Dual-Half-Bridge Resonant Converter with GaN E-HEMT for High Input Voltage Applications

Because the limitation of the voltage rating of gallium nitride enhancement mode high electron mobility transistor (GaN E-HEMT), the conventional resonant converter with GaN E-HEMT is not suitable for high input voltage applications. The cascoded dual-half-bridge resonant converter is more suitable for high input voltage applications because the voltage stress on power devices is reduced. Also, the efficiency is enhanced because zero voltage switching is achieved in reducing switching loss. Since the magnetizing components are integrated, higher power density can be reached. The operating principles and the steady-state characteristics of the cascoded dual-half-bridge resonant converter are analyzed. Finally, an experimental prototype is implemented with input voltage range of 740 V to 800 V, output voltage of 15 V, rated power of 105 W, and switching frequency of 500 kHz. The experimental results reveal that when input voltage is 800 V, the highest efficiency is 92.9% at 50% load, and the full load efficiency is 90.5%.