Influence of High Temperature on Electromagnetic and Mechanical Performances of High-Speed Permanent Magnet Machines

Generally, electrical machines are designed, analyzed, and optimized at standard room temperature (20°C), and the rise in temperature due to the heat generated by the electromagnetic losses is normally managed through cooling systems. In the electrically assisted turbocharger, the electrical machine operates in more challenging conditions where the ambient temperature is between 200°C and 300°C. This makes the development of high-temperature, high-performance machines is not only a safety issue but also a performance issue. Therefore, the impact of these high temperatures on the electromagnetic and mechanical performances of a high-speed permanent magnet synchronous machine (PMSM) intended for use in turbochargers is the subject of this study. Firstly, the changes in the electromagnetic and mechanical characteristics of the materials used in the SPM machine due to temperature variation are discussed. Moreover, finite element analysis (FEA) is used to make accurate predictions and comparisons about the electromagnetic performance of the PMSM running at 20°C and 200°C, including the airgap flux density, no-load voltage, output torque, torque-speed characteristics, electromagnetic losses and efficiency, and rotor mechanical stress. Finally, an individual design parameter optimization is carried out at 20°C and 200°C to highlight the influence of high temperatures on the predicted optimum values.