Designing High-Power Ultra-High-Speed Motor Using a New Multiphysics Multi-Objective Optimization Method for Mechanical Antenna Applications

Abstract

The conventional ultra-high-speed motor (UHSM) has been mostly developed for light load (or low power) applications (e.g., ~100W, 500 kr/min). However, the new mechanical antenna system requires a high-power UHSM. Accordingly, the conventional design approach of low-power UHSM cannot address the new challenges, especially with high-power design. The new challenges include lowered critical bending resonance (CBR) due to higher rotor aspect ratio ( $L/D$ ), ineffective electrical loading in the slotless stator due to commonly used three-phase winding, and significant temperature variation unusually in the axial direction and its mutual impact on the electromagnetic and mechanical performances. To address these new challenges, this paper proposes a quasi-3D thermal model to estimate critical temperature variations, a Rotordynamic model to limit CBR frequencies above the rated speed, and an electromagnetic model with multiphase winding to increase electrical loading in the slotless stator effectively. These models are systematically integrated to develop a unique Multiphysics multi-objective optimization (MMO) method, which enables (i) the mutual influence analysis among Multiphysics performances, such as thermo-electrical and thermo-physical that are critical in HP-UHSM, and (ii) a precise trade-off analysis between the efficiency and design safety margin (DSM). To validate the effectiveness of the proposed new MMO method, a 2-kW 500 kr/min UHSM, the highest power rated motor at this speed to the best of author’s knowledge, is designed for a mechanical antenna system and experimentally validated. It provides 94.5% efficiency with 30% DSM at 500 kr/min and no CBR below 11 kHz.

Keywords

• Multiphysics analysis
• multi-objective optimization
• permanent magnet motor
• six-phase motor
• safety margin
• ultra-high-speed motor