An Investigation of Temperature-Sensitive Electrical Parameters for SiC Power MOSFETs

This paper examines dynamic temperature-sensitive electrical parameters (TSEPs) for SiC MOSFETs. It is shown that the switching rate of the output current (<italic>dI</italic>_DS<italic>/dt</italic>) coupled with the gate current plateau <italic>(I</italic>_GP) during turn-ON could be an effective TSEP under specific operating conditions. Both parameters increase with the junction temperature of the device as a result of the negative temperature coefficient of the threshold voltage. The temperature dependency of <italic>dI</italic>_DS <italic>/dt</italic> has been shown to increase with the device current rating (due to larger input capacitance) and external gate resistance (<inline-formula><tex-math notation="LaTeX">$R_{G}^{\rm EXT}$</tex-math></inline-formula>). However, as <italic>dI</italic>_DS<italic>/dt</italic> is increased by using a small <inline-formula> <tex-math notation="LaTeX">$R_{G}^{\rm EXT}$</tex-math></inline-formula>, parasitic inductance suppresses the temperature sensitivity of the drain and gate current transients by reducing the “effective gate voltage” on the device. Since the temperature sensitivity of <italic>dI</italic>_DS<italic>/dt</italic> is at the highest with maximum <inline-formula><tex-math notation="LaTeX">$R_{G}^{\rm EXT}$</tex-math></inline-formula>, there is a penalty from higher switching losses when this method is used in real time for junction temperature sensing. This paper investigates and models the temperature dependency of the gate and drain current transients as potential TSEPs for SiC power MOSFETs.