Feasibility Study of Implementing a Hybrid Single- and Two-Phase Cooler for High Power Density Power Electronics

Abstract Thermal management is crucial in power module design nowadays, significantly influencing the cost, performance, and reliability of the traction inverters. As we strive for greater power density and smaller form factors, innovative thermal solutions become imperative. In this study, we explored a two-phase cooling method for the power electronics. The heatsink of a hybrid single- and two-phase cooler is integrated into a power module. We utilize surface enhancement features at the substrate-embedded evaporator to enable capillary-driven flow for passive coolant circulation and optimized phase separation. Additionally, a local reservoir is included in the cooler package that serves as a buffer to optimize the liquid supply to the evaporator. The two-phase cooling in our study leads to a high heat flux removal rate of 370 W/cm2 at a low superheat of 10 °C, and the coolant flow rate is less than 1 g/min, nearly 50 times lower than the pumped flow-based two-phase microcoolers. The feasibility of the completely passive operation is also studied. The proposed two-phase embedded cooler provides a promising solution for effective cooling and heat spreading of the next-generation power modules.