open access

https://doi.org/10.14943/doctoral.k15090

https://hdl.handle.net/2115/85629

Study of High-Power-Density Axial-Gap Motors Using Ferrite Permanent Magnets for EV/HEV

日本語

electric vehicles

2022-03-24

Hokkaido University

141p

With the recent tightening of regulations on carbon dioxide emissions, hybrid electric vehicles (HEVs) and electric vehicles (EVs) are becoming more and more popular worldwide. Permanent Magnet Synchronous Motor (PMSM) is often used as a drive motor (traction motor) in these vehicles. In order to expand the living space, it is essential to downsize the motor, i.e., a high-power-density is strongly required. This paper proposes two types of axial-gap motors using ferrite permanent magnets as a rare-earth less PMSM for in-wheel motor vehicle drives that can more easily secure the living space, and discusses how to increase its power density. First, a semi-closed-slot structure axial gap motor using soft magnetic composites, which can reduce the size and weight of a conventional axial gap motor, is proposed. In contrast to the open slot structure of the stator used in conventional motors, it was shown that the leakage flux could be reduced by using a half-closed slot structure with brims that enlarges the magnet opposing surface. As a result, it was shown from both the analysis and the actual test results that the same torque and efficiency characteristics as before can be obtained while reducing the amount of magnetic material and conductors in the motor. Secondly, a ferrite magnet consequent-pole-PM-type axial gap motor with a DC field winding was proposed to achieve high torque output comparable to that of rare earth magnets and high efficiency under light loads, which was difficult to achieve when using rare earth magnets. It was shown that the high torque output characteristic and the high efficiency characteristic, which are contradictory from the viewpoint of the field flux amount, can be combined by field operation using field windings. Furthermore, it was clarified that in order to achieve constant power operation up to the high speed range with high efficiency operation in the entire operation range, it is necessary to properly combine the field strengthening control with the field winding and the flux weakening control with the armature winding.

2022-03-24

甲第15090号

博士(工学)

(主査) 教授 小笠原 悟司, 教授 五十嵐 一, 教授 北 裕幸, 教授 竹本 真紹 (岡山大学・自然科学研究科)

情報科学研究科(システム情報科学専攻)

博士論文

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