Additively Manufactured Heat Exchanger for Improved Cooling of Electric Machines

This paper presents an additively manufactured heat exchanger, which is stacked together with stator laminations in the axial direction for high-performance cooling of the machine. The proposed heat exchanger encircles the stator slots and core, featuring coolant flow in the circumferential direction. The main advantage of the proposed cooling scheme is direct contact between the heat exchanger and the stator coils as well as the stator core. This advantage provides effective and direct cooling of stator coils and core, unlike conventional water jacket. Also, the cooling can be achieved without degradation in the slot fill factor, unlike in-slot cooling solutions. An IPM traction motor with 54 kW rating is presented as a case study. Thermal analysis indicated that the proposed heat exchanger could achieve 26 Arms/mm² current density in the stator windings.