Utilizing Electroluminescence of SiC MOSFETs for Unified Junction-Temperature and Current Sensing

Sven Kalker, Christoph H. van der Broeck, Rik W. De Doncker

Abstract

This work proposes a method for unified junctiontemperature and device-current sensing that utilizes the bodydiode electroluminescence of SiC MOSFETs. During conduction, the body diode of SiC MOSFETs emits light in the visible spectrum that is dependent on the device current and junction temperature. The sensing of this light offers the potential for a galvanically isolated and high-bandwidth junction-temperature and device-current measurement. Previous publications successfully showed that either temperature or current information can be extracted from the intensity of the emitted light if the other variable is known. However, they did not aim to independently extract the two variables. This work presents a unique extraction method that separately extracts device current and junction temperature by using intensity and wavelength information of the body-diode electroluminescence. The decoupled device-current and junction-temperature extraction works on the basis of multiple optical sensors with different wavelength sensitivities and artificial-intelligence techniques. This method is demonstrated via experimental evaluations using an automotive-grade SiC power module. Its integration in next generation power modules enables high-performance electrothermal monitoring for safe and reliable long-term operation.