Hybrid Solid- and Liquid-Cooling Solution for Isothermalization of Insulated Gate Bipolar Transistor Power Electronic Devices

Rapid increases in the power ratings and continuing miniaturization of power electronic devices have pushed chip heat fluxes well beyond the range of conventional thermal management techniques. The heat flux of power electronic devices for hybrid electric vehicles is currently at the level of 100-200 W/cm² and is projected to increase to 500 W/cm² in next generation vehicles. Such high heat fluxes lead to higher and less uniform insulated gate bipolar transistor (IGBT) chip temperature and significantly degrade the device performance and system reliability. Maintaining the maximum temperature below a specified limit, while isothermalizing the surface temperature of the chip, has become a critical issue for thermal management of power electronics. In this paper, a hybrid solid- and liquid-cooling system design, which combines cold plate liquid cooling and TE solid-state cooling, is proposed for thermal management of a 10 × 10 mm IGBT chip. The liquid-cooling cold plate is used for global cooling of the entire IGBT module while the embedded thin-film TE cooler (TEC) is employed for isothermalization of the individual IGBT chip. A detailed package-level 3-D thermal model is developed to explore the potential application of this cooling concept, with the primary attention focused on isothermalization and temperature reduction of IGBT chip associated with variations in TEC sizes, TE materials, applied current on TEC, cooling system designs, working fluid temperature, cold plate cooling capacity, and IGBT chip heat flux. The results demonstrate that the hybrid solid and liquid cooling is a very promising thermal management solution that can eliminate more than 90% of the temperature nonuniformity on the IGBT chip.