Comparison of Short-Term Over-current Capability of SiC Devices using Microchannel Cooling below and on top of the Chip

The typical fault clearance time in an AC grid is approximately 200 ms. Grid-connected power converters should be able to deliver increased currents during this time. This paper investigates the over-current (OC) capability using microchannel (MC) cooling below the chip using COMSOL simulations with SiC MOSFETs. The paper also compares thermal performance of MCs above and below the chip. The maximum allowable chip temperature is assumed to be 250 °C since SiC devices do not fail up to this temperature if the package is adapted for such operation. OC durations is from a few milliseconds to a few seconds. It is concluded that MC cooling below the chip can potentially increase the OC capability. However, the OC capability is significantly superior when MC cooling is applied on top of chip.