Design and performance evaluation of a DC-DC buck-boost converter with cascode GaN FET, SiC JFET, and Si IGBT power devices

Wide bandgap (WBG) semiconductors exhibit superior material properties, enabling power devices to operate at higher blocking voltages, switching frequencies, and junction temperatures. Power converters featuring WBG devices have higher power density and are more efficient and reliable than those using existing silicon (Si) devices. This paper presents the design of a non-isolated dc-dc buck-boost converter and evaluates the impacts of three power devices on converter performance. To evaluate overall performance, three buck-boost converters are designed and tested: one with a Cascode GaN FET, one with a SiC JFET, and one with a Si IGBT. Additionally, a SiC Schottky diode is implemented in each converter to reduce switching energy loss of power devices and improve converter performance. The switching behavior and energy loss of three power devices are evaluated at various junction temperatures. Total power loss and efficiency of each converter are compared at different switching frequencies, output power levels, and operating temperatures. The results show that the Cascode GaN FET-based converter yields considerable improvements in switching performance, total power loss, and overall efficiency.