Thermal measurement and analysis of packaged SiC MOSFETs

• New method to characterize the transient thermal resistance of packaged SiC MOSFETs.
• The junction temperature of SiC MOSFETs is measured with supplying constant power.
• The transient thermal resistance is characterized with discrete time constants.
• The thermal model parameters are characterized using thermal structure functions.

This paper reports an approach for transient thermal resistance measurement and thermal analysis of packaged SiC MOSFETs. A relationship of gate-source voltage (VGS) and temperature of a SiC MOSFET measured using constant current pulses of 2 A that have width of 200 μs is employed to measure junction temperature. The transient thermal resistance of the packaged SiC MOSFET is measured with constant current injection of 2 A in heating condition. A modified thermal resistance analysis by an induced transient (TRAIT) method is introduced. The measured transient thermal resistance is characterized with a discrete time constant spectrum, and analysed using structure functions based on a Cauer equivalent thermal model. The partial thermal resistances of the packaged SiC MOSFET were extracted and compared to the results from the thermal model based on finite difference method (FDM), and comparison shows good agreement between both results.