In-Wheel Motor System of Multiple High Speed Motors Integrated with Magnetic Gear for Electric Vehicle

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14724
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 21010:Power engineering-related
• Research Institution: Shibaura Institute of Technology (2021-2023); Waseda University (2020)
• Principal Investigator: Aiso Kohei 芝浦工業大学, 工学部, 准教授 (60844206)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 磁気ギア / 高速モータ / 電気自動車

Outline of Final Research Achievements

In this study, an in-wheel motor system integrating magnetic multiple spur gears (MMSG) and multiple high-speed motors was proposed to reduce the size and weight of motor systems and to achieve higher efficiency for electric vehicles. As a result of the research, it was clarified through experiments that prototype machine can achieve the gear efficiency of more than 90% and the gear torque density of 158 kNm/m^3 in the high-speed range up to 42,000 rpm. This achievement shows that magnetic gears can achieve high speed drive, high efficiency, and high torque density. In addition, a control method for driving multiple high-speed motors with high efficiency by a simple and inexpensive system was clarified.

Free Research Field

電力工学関連

Academic Significance and Societal Importance of the Research Achievements

磁気ギアは非接触での動力伝達が可能であり, メンテナンスフリー, 低振動, 低騒音, 伝達効率が高い利点がある。しかし, 従来の磁気ギアの多くは動作原理が磁束変調方式に基づいているため, 高速回転時には高調波磁束に起因した損失増大や入力ロータの機械強度の課題があり, 自動車のように入力モータの回転速度が10,000rpm以上の用途に適用することは困難であった。本研究により新しい磁気ギア(MMSG)が提案され, 実機実験により高速駆動, 高トルク密度, 高効率が達成されたことは, 磁気ギアの高速化に向けた有用な成果であり, EV用モータシステムの小型軽量化と高効率化に貢献できる成果である。