Novel Refrigerant Cooling Method for Traction Motor Thermal Management

This paper proposes a novel refrigerant cooling system for electric vehicle traction motors, replacing traditional 50/50 water-ethylene glycol cooling to improve thermal management and performance. The system, integrated with copper pipes and epoxy potting material within axial channels, was evaluated through comprehensive electromagnetic and thermal simulations using the Hyundai IONIQ 5 rear motor as a reference. The simulations, conducted under rated and peak conditions, showed significant reductions in winding temperatures—up to 43°C under rated conditions and 33°C under peak conditions. These results suggest that refrigerant cooling can support higher power densities, more compact motor designs, and extended motor lifespan while effectively managing condensation risks. Additionally, the analysis applies to R1234yf, with a heat transfer coefficient reaching up to 98% of R134a's in the same geometry, demonstrating that this cooling method can adapt to alternative refrigerants.