Thermal Modelling of Advanced Rotor Cooling Solutions for Traction Applications

Guiducci, A; Wrobel, R; Nuzzo, S; Barater, D; Franceschini, G

doi:10.1109/ICEM60801.2024.10700224

Thermal Modelling of Advanced Rotor Cooling Solutions for Traction Applications

Lookup NU author(s): Dr Rafal Wrobel

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

This paper explores alternative thermal management techniques of a rotor assembly of a high-speed salient polewound-field synchronous motor for traction applications. In general, the rotor assembly of an electrical machine is very challenging in terms of effective heat removal. This is due to nature of the rotary part with a limited thermal path for extracting the generated heat. Further to this, factors like system integration and additional mechanical power loss need to be carefully considered for a well-balanced thermal management/electrical machine design. In this work, the authors investigate several selected cooling techniques, which involves passing a fluid (air and/or oil-based coolant) through the rotor assembly. To aid the analysis, a number of design tools have been developed/used including a simplified correlation-based thermal equivalent-circuit (TEC), a finite element (FE) method and a finite volume computational fluid dynamics (CFD). The proposed methodology offers a computationally efficient approach, with the TEC used for initial trade-off study, and high-fidelity detailed CFD employed at later stage of the development process. A case study motor design is used here, to demonstrate the methodology. The initial theoretical predictions suggest that the active rotor cooling offers clear performance gains, as compared with the baseline rotor design with passive heat removal. Both convective heat transfer coefficient (HTC) and rotor power loss handling are discussed in the context of the overall motor performance/torque-speed envelope. Moreover, comments regarding the thermal management and motor systemintegration, and additional mechanical power loss are provided.