A Comparative Design and Performance Study of a Non-Isolated DC-DC Buck Converter Based on Si-MOSFET/Si-Diode, SiC-JFET/SiC-Schottky Diode, and GaN-Transistor/SiC-Schottky Diode Power Devices

Conventional silicon (Si) based power devices are commonly used in industrial battery charging applications. In most cases, fast switching operation is desired in such applications in order to have a compact power converter system in terms of size and weight, while in contrast, it drives for large switching losses. The maturity of wide bandgap (WBG) technology provides enormous opportunities to ameliorate fast switching capabilities, high blocking voltage abilities, and high temperature operating conditions for power devices. This paper presents a comparative design and performance study of a non-isolated dc-dc buck converter based on three combinations of power devices: Si-MOSFET/Si-diode, SiC-JFET/SiC-Schottky diode, and GaNtransistor/SiC-Schottky diode for industrial applications. Characterization of the switching behavior of each power device and evaluation of switching energy losses are presented and discussed. Furthermore, the overall converter efficiency at high switching operations as well as with a wide operating range of input voltages, and the converter power density to size ratio are studied and reported. Results are shown that the GaN-transistor/SiC-Schottky diode and SiC-JFET/SiC-Schottky diode based converters exhibit significant lower switching energy losses and less total converter power loss, and thus a more efficient performance compared to the Si-MOSFET/Si-diode based converter. Through the analysis performed, it is shown that the hybrid combination of the GaN-transistor/SiC-Schottky diode followed by the SiC-JFET/SiC-Schottky diode combination are the most robust options for a high performance, high power density with smaller size non-isolated dc-dc buck converter for harsh operating conditions.