Protection for normally on SiC JFET
With the increasing demand for power converters and high power densities, and Silicon (Si) is reaching its theoretical limits, Silicon Carbide (SiC) is the object of a growing interest. It possesses several advantages over Si, among which: lower on resistance and operation at higher temperatures . This makes of SiC transistors, and more generally SiC power converters , the ideal candidates for use in hybrid and electric cars. Only one type of SiC transistor is close to commercial production: the Junction Field Effect Transistor (JFET). However, it is a normally- on device, i.e. it needs a negative voltage to be turned off. Therefore it needs protection when used in a circuit, as a fault in the driver power supply would turn on the JFET and possibly lead to short-circuits .
The invention proposes a way of solving the problem while retaining the advantages of using a SiC transistor. Therefore it does not add switching losses and does not impede the high temperature operation.