A Novel Method for Real-Time Junction Temperature Monitoring of SiC mosfet Through Sensitivity Amplification of Turn-off Delay Time

Junction temperature is a critical silicon carbide (SiC) semiconductor parameter for thermal management and health condition monitoring. To monitor the junction temperature, the temperature-sensitive electrical parameter (TSEP) method is gaining increasing attention. Among the TSEPs of the SiC mosfet, the turn-off delay time has good linearity over a wide temperature range. However, the temperature sensitivity of the turn-off delay time of SiC mosfet is low. In existing solutions for turn-off delay time, the gate drive resistance is increased to prolong the turn-off delay time and enhance the temperature sensitivity, affecting the switching process of the device under test (DUT) and increasing switching loss. To address these challenges, a novel real-time junction temperature monitoring method is proposed for turn-off delay time. The proposed method amplifies the temperature sensitivity of the turn-off delay time without increasing the gate drive resistance. The gain of the temperature sensitivity amplification can be easily adjusted by changing the detection circuit parameters. According to the test results, the temperature sensitivity of the turn-off delay time is successfully amplified by the detection circuit with a gain of 60.90331 (which is close to the setting value of 61), without affecting the switching process of the DUT. Once the DUT is turned off, the detection circuit can detect the turn-off delay time and output a wide pulse signal, whose pulse width exhibits good linearity and high temperature sensitivity over a wide temperature range, allowing it to be directly tested by a microcontroller.