Developments of Control and Design strategies for Slotless Permanent Magnet Motors using High Energy Density Magnets

作为全球环境保护的节能战略之一，电机驱动系统的效率提高在家电和工业应用中得到了促进。其中，利用高能量密度稀土磁体的无槽永磁同步电机（Slotless PMSM）从有效利用稀土磁体的角度受到了广泛关注。本课题的目标是开发高效无槽永磁同步电机的优化设计和控制策略，在研究期间我们取得了以下成果：考虑到绕组电感值对设计高效率无槽永磁同步电机的重要意义，提出了一种新的优化设计策略。根据优化设计结果，利用三维有限元分析（3D-FEM）制作了第二台样机，并对其驱动性能进行了实验评估。结果证实，与第一原型相比，第二原型可以实现25%的载流子损耗减少。通过三维有限元分析，我们发现，随着频率的增加，绕组电感的减小和绕组电阻的增加是由于Ne-Fe-B永磁体表面的涡流损耗造成的。在此基础上，提出了一种无槽永磁同步电机设计阶段载流子损耗的定量预测方法，并通过第二样机的实验验证了所提方法的有效性。

As one of strategies for saving energy in global environmental conservation, the efficiency improvements of electric motor drive systems have been promoted in home appliances and industrial applications. Among them, Slotless Permanent Magnet Synchronous Motor (slotless PMSM) using recently developed rare-earth magnets with high energy density have been received much attention from a standpoint of effective use of rare-earth magnets. An aim of this project was to develop the optimum design and control strategies for high efficiency slotless PMSM and during research period we had made achievements as follows.1. Considering that winding inductance value is important for designing high efficiency slotless PMSM, we proposed the new optimum design strategy modifying the design strategy of the first prototype. We made the second prototype according to the result of the optimum design using three-dimensional Finite Element Analysis (3D-FEM) and experimentally evaluated the drive performances. As a result, it was confirmed that the second prototype could realize the decrease in carrier loss by 25% compared to the first prototype.2. By using 3D-FEA, we identified the fact that the decrease in the winding inductance and the increase in the winding resistance for an increase in frequency are due to the eddy current loss on the surface of Ne-Fe-B permanent magnets. Based on the above investigation, we proposed a method for the quantitative prediction of the carrier loss at the design stage of slotless PMSM and confirmed the effectiveness of the proposed method by the experiments using the second prototype.