Scaling of High-Speed Surface PM Bearingless Machines

This paper presents an approach for rapidly and accurately scaling Bearingless Surface Permanent Magnet Machines (BSPMs) across a range of speeds and power, with aim to explore the performance potential and trade-offs across the design space of ultra-high-speed BPSMs. A computationally-efficient scaling algorithm with consideration of rotordynamic, structural, and current density limitations is proposed. The algorithm is applied to scale a 7.6kW, 160 kr/min reference BSPM to 10.4kW as a detailed case study, with FEA validation demonstrating the efficacy of the scaling approach. The validated algorithm is utilized to generate an example design space, and limiting constraints for achieving higher power and power density in BSPMs is identified. This study identifies that combined rotor structural and rotordynamic constraints limit the maximum achievable power at any given speed, while rotor structural and maximum slot current density constraints limit the maximum achievable speed when using the proposed scaling approach.