Comparison of Top and Bottom Cooling for Short Duration of Over-Currents for SiC Devices: An Analysis of the Quantity and Location of Heat-Absorbing Materials

Abstract

The fault clearance time in the power system can vary from a few milliseconds to a few hundred milliseconds. Power electronics converters should be able to provide the increased current during faults without failing due to thermal limits. Hence, the heat generated in the semiconductor chip due to the over-current (OC) should be removed as soon as it is generated. In this paper, cooling by heat-absorbing material has been investigated on the top, bottom, and top + bottom of the SiC MOSFET chip using COMSOL simulations for OCs. The heat-absorbing materials considered in the paper are copper, graphite, and aluminum. The maximum allowed chip temperature is assumed to be 250 °C since SiC devices do not fail in this range of temperature. It is concluded that the cooling on the top of the chip has the best performance among the three arrangements discussed in the paper in terms of OC duration and steady-state temperature. Another conclusion is that copper has the best performance due to higher thermal capacity for the same volume of the heat-absorbing material.