Current Sharing and Overvoltage Issues of Paralleled SiC MOSFET Modules

The development of the medium voltage wideband gap semiconductor SiC power devices has enabled several applications. Most of these medium voltage high power applications require parallel connections of the power modules to reach the desired current ratings. With high switching speeds of the SiC modules, the paralleling of the modules must be done properly to ensure the safe operation of the devices. The parameter variations among the paralleled modules, variation of gate drive signals, modules layout and associated parasitic elements are the key things affecting the current sharing among the modules and the voltage overshoot across the devices. Careful design consideration must be done addressing all of the above issues to ensure good current sharing and voltage overshoot in paralleled SiC Modules. In this paper, switching performance of the three paralleled SiC MOSFET modules switching at 1250V, 1300A is presented. The details of the gate driver for driving three modules in parallel is presented and importance of good layout is discussed by comparing two different gate driver layouts. The effect of load cable coupling on current sharing is analyzed. Also, a turn off over voltage situation when there is parameter mismatch among the paralleled modules is presented.