Primary-Side Current Based SR Control for High Voltage and High Frequency Cascoded Dual Half-Bridge Resonant Converter

In the paper, the cascoded dual-half-bridge (CDHB) resonant converter is implemented with the GaN power devices for high-input voltage applications because the voltage stress on power switches is reduced. Since power devices of the CDHB resonant converter can be operated with soft-switching, the system efficiency is increased and therefore increasing the switching frequency and the power density of the converter. In this paper, the primary-side current is detected to generate the control signal of the secondary-side synchronous rectifiers, reducing conduction losses. Finally, an experimental prototype of the CDHB resonant converter with the presented primaryside based synchronous rectification control method is implemented. The input voltage range is 740 V to 840 V, the output voltage is 15 V, the rated power is 105 W, and the series resonant frequency is designed at 1 MHz. At the input voltage of 800 V and the current output of 4.2 A condition, the highest efficiency is achieved at 94%.