Power Conversion With SiC Devices at Extremely High Ambient Temperatures

TLDR

The study evaluates the suitability of SiC JFETs and Schottky barrier diodes for high‑temperature power electronics. SiC JFETs and SBDs were packaged for high‑temperature operation, their dc characteristics measured from 25 °C to 450 °C, and a 100 V 25 W dc‑dc converter was designed and tested up to 400 °C based on those measurements. Both devices function at 450 °C—unlike conventional Si—though the JFET current and conduction loss decline with temperature while the SBD current remains constant, demonstrating SiC suitability for aerospace and automotive harsh‑temperature applications.

Abstract

This paper evaluates the capability of SiC power semiconductor devices, in particular JFET and Schottky barrier diodes (SBD) for application in high-temperature power electronics. SiC JFETs and SBDs were packaged in high temperature packages to measure the dc characteristics of these SiC devices at ambient temperatures ranging from 25degC (room temperature) up to 450degC. The results show that both devices can operate at 450degC, which is impossible for conventional Si devices, at the expense of significant derating. The current capability of the SiC SBD does not change with temperature, but as expected the JFET current decreases with rising temperatures. A 100 V, 25 W dc-dc converter is used as an example of a high-temperature power-electronics circuit because of circuit simplicity. The converter is designed and built in accordance with the static characteristics of the SiC devices measured under extremely high ambient temperatures, and then tested up to an ambient temperature of 400degC. The conduction loss of the SiC JFET increases slightly with increasing temperatures, as predicted from its dc characteristics, but its switching characteristics hardly change. Thus, SiC devices are well suited for operation in harsh temperature environments like aerospace and automotive applications.