Online Junction Temperature Measurement Of SiC MOSFET In Practical Converters

Junction temperature is critical for reflecting the health of power semiconductor devices. However, the junction temperature extraction circuit of SiC MOSFET based on temperature sensitive electrical parameters (TSEPs) are difficult to apply in practical converters. This paper uses a new measurement circuit to extract peak voltage. The circuit can be integrated in the driving circuit, and realizes automatic, accurate and fast online real-time extraction in each switching cycle without additional control signals and is independent of the main circuit electromagnetic interference. Furthermore, the accuracy of the system is verified in the double-pulse test circuit and Boost convertor. The double-pulse test results show that the peak voltage can be accurately extracted and has a sensitivity of −0.32 mV/°C. Importantly, the circuit proposed in the boost converter can also work normally without interference from the main circuit, and has a sensitivity of −0.33 mV/°C, which is basically the same as the double-pulse test circuit.

I Introduction

SiC MOSFETs are widely used in power electronic converters with the advantages of high switching speed, high power density, high juncture temperature, low resistance, high blocking voltage, etc [1]–[3]. The complex and harsh working conditions are demand for a higher reliability power system, while the power semiconductor failure accounts for the highest proportion in all failure cases, so health monitoring of power semiconductors is of great significance. It is very important to obtain the junction temperature of the device without affecting its normal function during the operation of the converter.