A Transistor Clamp Circuit of On-state Voltage Drop for SiC MOSFET Temperature Monitoring

To ensure the long-term reliability of power electronic systems, accurate junction temperature monitoring of Silicon Carbide (SiC) MOSFETs is essential, as excessive thermal stress is a major cause of device degradation and failure. This paper addresses the challenge of real-time, non-intrusive temperature monitoring by proposing a fast-response measurement circuit based on the on-state voltage drop (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</inf>), a temperature-sensitive electrical parameter. A theoretical linear correlation between (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</inf>) and junction temperature is established, enabling reliable thermal state estimation during normal operation. The proposed circuit accurately extracts (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</inf>) within 0.6 µs during device conduction and effectively suppresses voltage spikes during the off-state through voltage clamping. This design eliminates the need for complex auxiliary circuits, reduces monitoring latency, and enhances measurement precision. Its simplicity, robustness, and high temporal resolution make it particularly suitable for predictive maintenance, fault prevention, and thermal management in high-efficiency applications such as renewable energy inverters, electric vehicle powertrains, and smart grid systems.