Heat pipes for thermal management of electric vehicle motors: A review

With the evolution of automotive drive motors towards high power density, traditional single cooling paths have limitations in breaking through series thermal resistance. Heat pipes achieve near isothermal heat transfer through latent heat of phase change, and can be connected in parallel with low thermal resistance channels to enhance motor cooling. This article systematically reviews the research progress of heat pipe assisted cooling technology in three systems: air cooling, water cooling, and oil cooling, based on the unified framework of “working fluid - evaporation section heat extraction structure - condensation section heat dissipation interface”. The design propositions and trade-off rules of the stator/rotor side three elements were compared around the dual dimensions of cooling medium and heat source location. The results indicate that the function of the heat pipe evolves progressively with the cooling medium, from the “strengthening force” in air cooling and the “advancing force” in water cooling to the “blind spot filling force” in oil cooling; The focus of the three element design is determined by the characteristics of the cooling terminal, with the condensing section being most affected by the medium. The current bottleneck lies in the gap between laboratory performance and engineering long-term reliability. This article points out that the theory of rotating working fluid reflux, multi physics field collaborative design, and vehicle accelerated ageing verification are the core directions to promote the engineering of this technology.