Online Accurate Measurement of Steady-Thermal Resistance of SiC MOSFETs for DC Solid-State Power Controller

The steady-state thermal resistance Rthis the key characteristic of SiC MOSFETs, usually used as a failure indicator. Due to the operating mode of SiC MOSFETs in the dc solid-state power controller (dc-SSPC), the junction temperature measurement based on the steady on-state resistance Rdsonof SiC MOSFETs is vital to the accurate online measurement of Rth. The accuracy of a digital oscilloscope is limited by its analog-to-digital converter; therefore, a drain-source voltage clamp circuit (DVCC) needs to be employed for the accurate online Rdsonmeasurement. However, conventional DVCCs are unsuitable for either the use over a wide range of operating temperature Twor the integration into the dc-SSPC due to their bulk package. Therefore, in this article, a new design of DVCC is proposed that commonly used small-sized components can be easily integrated into the dc-SSPC with a little impact on its overall volume and can accurately perform the online Rdsonmeasurement. The experimental results verify the high Rdsonmeasurement accuracy (wrange (25-100 °C), as well as, the accurate online measurement of Rthwith an accuracy of 2.3%. The application of the proposed DVCC in the accelerated power cycling tests highlights its potential in the lifetime prediction.