An Electric Motor Thermal Bus Cooling System for Vehicle Propulsion - Design and Test

Automotive and truck manufacturers are introducing electric propulsion systems into their ground vehicles to reduce fossil fuel consumption and harmful tailpipe emissions. The mobility shift to electric motors requires a compact thermal management system that can accommodate heat dissipation demands with minimum energy consumption in a confined space. An innovative cooling system design, emphasizing passive cooling methods coupled with a small liquid system, using a thermal bus architecture has been explored. The laboratory experiment features an emulated electric motor interfaced to a thermal cradle and multiple heat rejection pathways to evaluate the transfer of generated heat to the ambient surroundings. The thermal response of passive (e.g., carbon fiber, high thermal conductivity material, thermosyphon) and active cooling systems are investigated for two operating scenarios. The test results demonstrate that up to 93% improvement can be achieved in cooling system energy consumption during a light load electric motor condition while maintaining a target core temperature of 70°C. The governing thermal system dynamics will be reviewed in discussion of the experimental observations.