An All-SiC High-Frequency Boost DC–DC Converter Operating at 320 °C Junction Temperature

This letter presents the design, prototype development, operation, and testing of an 800 kHz, 1 kW, 800 V output boost dc-dc converter module that integrates SiC MOSFET and SiC Schottky diode die. It is observed that when the device loss is dominated by switching loss, the steady-state junction temperature of SiC MOSFET can reach as high as 320°C. This is the highest self-heated junction temperature operation of SiC power devices under room temperature ambient reported in the literature. The high-frequency switching characteristics and high-temperature thermal reliability of the assessed converter are evaluated in detail. A solder-molten phenomenon during high junction temperature operation is detected and the die-attachment material is thus improved to enhance the high-temperature thermal reliability of the converter module. This study shows that the high-frequency capability of a gate driver and high-temperature die-attachment technology can be limiting factors preventing SiC power devices from operating at higher junction temperatures.