Toward Direct Cooling In High Voltage Power Electronics: Dielectric Fluid Microchannel Embedded Source Bussing Terminal

A strategy for providing semi-direct cooling of SiC MOSFETs in an extreme power dense half-bridge module, while also serving as a source terminal interconnection is presented. This bussing structure with integrated cooling function provides topside (source) connection to 16 paralleled devices within a low inductance, 1.7kV rated power module. Dielectric fluid coolant (HFE7500) in the microchannel manifold sustains the voltage discharge risk in the fluid but while not introducing risks associated with flooding the module with coolant. Meanwhile, it also achieves a low thermal resistance pathway between device to coolant as a single phase coolant. Thermal characterization has been performed illustrating an effective thermal resistance of 0.54 cm ² -°C/W across the 16 devices, with ample room for increased performance with optimized device topside attachment. This cooling approach inside of a bussing connector has the opportunity to increase module + cooler power density up to 4-5x of a traditional single sided module, as well as reduce the thermal coupling effects inside a module.