Thermal design of high power-density additively-manufactured induction motors

The objective of this paper is to present the thermal and mechanical stress analysis of an additively manufactured induction motor for traction applications. The additive manufacturing process enables higher copper fill factors in the stator core of the machine and also improves the internal thermal conduction in the stator core. While a higher copper fill factor increases the machine power density, it comes at the cost of higher heat dissipation density. This poses new challenges for the machine thermal management and its reliability due to the operational thermo-mechanical stresses. Thermal stress analysis has been presented for various electromagnetically optimized machine designs at a rated power of 30 kW. Maximum current density in the stator is predicted for varying machine size, cooling schemes, and maximum allowable temperature in the stator slot. It is shown that liquid cooling of the induction machine can achieve stator current density > 20 A/mm² in the stator for a rated power of 30 kW.