High Frequency Half-Bridge Resonant Converter with Synchronous Rectification for High Input Voltage Applications

With the rapid development of gallium nitride (GaN) power devices, they have been widely utilized for high-frequency applications to enhance the system efficiency and power density. However, the voltage blocking capability of GaN power devices is limited, constraining the applications of GaN power devices for high input voltage applications. An input series/output parallel (ISOP) half-bridge (HB) resonant converter is adopted in this research. The voltage stress on primary-side power switches is reduced and the conduction losses caused by the secondary-side rectifiers are also reduced due to parallel operation. Furthermore, HB resonant converter has the characteristic of soft switching in decreasing the switching losses in power components. GaN power devices are employed. Also, ANSYS is used for design of the planar transformers in high-frequency applications. Then, the control driving signals for secondary-side synchronous rectifiers (SRs) are generated by sensing resonant current to increase the efficiency of the converter. Finally, an ISOP HB resonant converter is built with input voltage of 740-840 V, output voltage of 200 V, series-resonant frequency of 1 MHz, and output power of 2.7 kW. The experimental results show that the highest efficiency of the ISOP HB resonant converter is 98.2% at output power of 1.35 kW, while the efficiency of full load at 2.7 kW is 95.9%.