Drive Train Cooling Options for Electric Vehicles

Electrification of vehicles intensifies their cooling demands due to the requirements of maintaining electronics/electrical systems below their maximum temperature threshold. In this paper, passive cooling approaches based on heat pipes have been considered for the thermal management of electric vehicle (EV) traction systems including battery, inverter, and motor. For the battery, a heat pipe base plate is used to provide high heat removal (180 W per module) and better thermal uniformity (<5°C) for the battery modules in a pack while downsizing the liquid cold plate system. In the case of Inverter, two phase cooling system based on heat pipes was designed to handle hot spots arising from high heat flux (~100 W/cm²)–for liquid cooling and provide location independence and a dedicated cooling approach-for air cooling. For EV motors, heat pipe-based systems are explored for stator and rotor cooling. The paper also provides a glimpse of development on high-performance microchannel-based cold plate technologies based on parallel fins and multi-layer 3D stacked structures. Specifically, this work extends the concept of hybridization of two-phase technology based on heat pipes with single-phase technology, predominately based on liquid cooling, to extend performance, functionalities, and operational regime of cooling solutions for components of EV drive trains. In summary, heat pipes will help to improve and extend the overall reliability, performance, and safety of air and liquid cooling systems in electric vehicles.