Investigation of power MOSFETs for high temperature operation

This paper investigates the power MOSFETs high temperature operation from the standpoint of thermal stability. The objective is to identify the electrical and thermal limitations to high temperature and high frequency application of power MOSFETs, and to provide guidelines on how to use them safely and reliably for high temperature operation. Power MOSFETs DC blocking characteristics at high temperatures are studied experimentally and analytically. The loss characteristics including the switching loss, conduction loss, and leakage are tested and analyzed at higher junction temperature. A closed loop thermal system and stability criteria is developed and analyzed. At high switching frequency operation, the switching loss determines the thermal stability. When the junction temperature increases higher, the high leakage current loss can cause thermal instability. From the developed thermal stability system, the maximum witching frequency can be derived for the converter system design. The developed thermal system analysis approach can be extended to other Si devices including IGBT or wideband gap devices such as SiC power MOSFETs.