High temperature testing of a buck converter using silicon and silicon carbide diodes

The More Electric Initiative demands (MEI) high temperature and high power electronic circuits for use in power management and distribution in advanced aircraft systems. In an attempt to develop electronic power devices for high temperature application, SiC diodes were performance mapped for dynamic characterization in the temperature range of 25°C to 300°C. Similar high temperature dynamic characterization was performed on SiC MOSFETs in the temperature range of 25°C to 300°C. In order to compare the advantages of enhanced SiC device performance at elevated temperatures over Si devices, Si and SiC devices were studied in a buck type DC/DC converter circuit. The present research is geared towards the investigation of thermal effects at high temperatures on the performance characteristics of the buck converter circuit. SiC devices are capable of operating at higher voltages and temperatures when compared to Si devices. To investigate these advantages, Si MOSFETs and Si diodes were used in a Si based buck converter circuit at elevated temperatures. A Si MOSFET and SiC diode were initially used in the buck converter circuit. Performance characteristics of this converter circuit were generated at elevated temperatures. The converter utilizes a Si MOSFET with a Si or SiC Schottky diode, Schottky diodes were preferred over p-n diodes as the reduced on-voltage results in improved efficiency. Performance characteristics were measured to determine the effect of temperature of the on-resistance of the MOSFET, efficiency and DC voltage transfer function (M_vdc) of the converter