Liquid Jet Impingement Cooling of PowerConversion

Thermal management of power electronics is an extremely challenging problem in the harsh environment of military hybrid vehicles, where the local air and liquid coolant’s temperature exceed 100 °C under regular operating conditions. This paper presents the development work of a high heat flux, jet impingement-cooled heat exchanger for a 600-V/50-A silicon carbide (SiC)power module (rated at 175 °C device junction temperature), used for bidirectional power conversion between a 28-V battery and a 300-V dc bus. A total of 50 volume% mixture of water-ethylene glycol (WEG) coolant at 100 °C inlet temperature is the only available coolant.

An array of WEG coolant microjets impinges on the base plate of the SiC module. The jet impingement cooling system has been optimized by experimental studies on a surrogate module, along with a high-fidelity computational model, to accurately estimate the SiC device junction temperature in relevant operating conditions. Results indicate that at the design heat load of 151 W (worst-case scenario), the SiC device junction temperature is reduced from 290 °C with commercial-off-the-shelf (COTS) cold plate cooling and 215 °C with COTS microchannel heat exchanger cooling, to 169 °C with a jet impingement-cooled heat exchanger, using the same flow rate.