Evaluation of Two-Phase Cold Plate for Cooling Electric Vehicle Power Electronics

Rapid increases in the power ratings and continued miniaturization of semiconductor devices have pushed the heat flux of power electronics well beyond the range of conventional thermal management techniques, and thus maintaining the IGBT temperature below a specified limit has become a critical issue for thermal management of electric vehicle power electronics. Although two-phase cold plates have been identified as a very promising high flux cooling solution, they have received little attention for cooling of power electronics. In this work, a first-order analytical model and a system-level thermal simulation are used to compare single-phase and two-phase cold plate cooling for Toyota Prius motor inverter, consisting of 12 pairs of IGBT’s and diodes. Our results demonstrate that with the same cold plate geometry, R134a two-phase cooling can substantially reduce the maximum IGBT temperature, operate all the IGBT’s at very uniform temperatures, and lower the pumping power and flow rate in comparison to single-phase cold plate cooling. These results suggest that two-phase cold plate can be developed as a low-cost, small-volume, and high-performance cooling solution to improve system reliability and conversion efficiency for electric vehicle power electronics.