Investigation of SiC Stack and Discrete Cascodes

The SiC cascode switch integrates the advantages of a Si MOSFET and the excellent high voltage, high frequency and high temperature properties of the SiC normally-on JFET. It has a normally-off operation mode, simple gate drive, and a reliable MOS gate without the threshold voltage drift. These superior features make the SiC cascode device the best candidate for realizing a "smaller, faster and cheaper" power conversion system. The cascode can be constructed in discrete configuration or in stack configuration. In this work, the switching performance, short-circuit withstand capability and unclamped inductive switching (UIS) capability of 1.2kV SiC discrete and stack cascodes are investigated by performing experiments and numerical simulations. Simulation results show that the silicon MOSFET in the stack cascode does not limit the short circuit and UIS capabilities of the stack cascode.