Cooling System Design and Temperature Field Analysis for High-Speed Switched Reluctance Motor Considering Multi-Field Coupling of Electromagnetic-Thermal-Flow

Given the challenges of high loss density and heat dissipation in high-speed switched reluctance motors (HSRMs), this paper proposes a thermal analysis and cooling design method based on electromagnetic-thermal-flow (EM-TF) coupling. A 3 kW, 20,000 r/min HSRM is investigated. Accurate models of AC copper and windage losses are developed using fine 3-D winding modeling and full-domain CFD, enabling realistic heat source distribution. The total losses, including copper, core, and windage losses, are used as inputs for thermal simulation. Three cooling structures are compared in terms of thermal and flow field performance, and the spiral waterway is identified as optimal. To improve prediction accuracy, both unidirectional and bidirectional EM-TF coupling methods (UEMTFC and BEMTFC) are employed. The latter considers temperature-dependent properties of materials and internal air. Results show that BEMTFC significantly improves thermal prediction, with winding temperature deviations under $4~^{\circ }$ C compared to experimental results. These results confirm the effectiveness of the proposed method in improving the accuracy of thermal analysis for high-speed electrical machines.