Additive Manufacturing of electric machines: Research on the potential of additivemanufacturing of PM synchronous machine rotors

附加制造工艺无需使用成形工具，就可以一层一层地生产零部件和组件。此过程在设计零部件的几何图形以及设计材料特性时会产生额外的和新的自由度。本研究项目的重点是利用这些新的自由度来改进电机的设计和制造，特别是永磁同步电机转子的设计和制造。在之前的研究中，帕德伯恩大学直接制造研究中心(DMRC)和汉诺威莱布尼茨大学驱动系统和电力电子研究所(IAL)密切合作，获得了关于AM的不同材料系统、其表征及其在电机中应用的基础知识。本文提出的研究项目涉及“AM材料研究”、“转子设计”、“转子制造”和“转子试验”等领域。在材料研究方面，通过系统的参数研究，确定了适用于电机的软磁材料和相应的AM工艺参数。重点放在一个FeCo和两个FeSi合金上。为了对这些材料进行表征，应在AM试件上测定其电、磁和结构力学性能。这些结果将用于永磁同步电机转子设计的二期工程。应利用已确定的材料特性和AM在设计中产生的新自由度来改进PMSM的可制造性和技术参数，例如，通过在不增加PM泄漏磁通的情况下进行转子倾斜，以及通过特殊的表面成形来减少转子表面的涡流。对于这些新的AM转子概念，电磁和机械设计都需要设计规则。在项目的第三阶段，原型转子应由AM制造，如果需要，还应进行机械或热后处理。最后，将通过实验对这些转子进行评估，以验证预测的电磁和机械性能以及运行行为，如扭矩密度、效率和扭转强度。为了证明AM对电机制造的好处，应通过模拟和测量将其与传统制造的转子进行比较。

Additive manufacturing processes produce components and assemblies layer by layer without using formative tools. This process generates additional and new degrees of freedom in designing the geometry of the components as well as in designing the material properties. The focus of this research project is to use these new degrees of freedom for improving the design and manufacturing of electrical machines, especially of rotors of permanent magnet excited synchronous machines (PMSM). In previous research, fundamental knowledge on different material systems for AM, their characterization and their application in electrical machines were achieved in tight cooperation between the University of Paderborn's Direct Manufacturing Research Center (DMRC) and the Institute for Drive Systems and Power Electronics (IAL) of Leibniz Universität Hannover. The research project proposed here addresses the fields 'material research for AM', 'rotor design', 'rotor manufacturing' and 'rotor test'. On the field of material research, suitable soft magnetic materials for electrical machines and the respective process parameters for AM are identified by means of systematic parameter studies. The focus lies on one FeCo and two FeSi alloys. In order to characterize these materials, their electrical, magnetic and structural mechanic properties shall be determined on AM test specimen. These results shall be used in the second phase of the project for designing rotors of PMSM. The identified material properties and the new degrees of freedom in design due to AM shall be used to improve the manufacturability and the technical parameters of PMSM, e.g. by rotor skewing without increasing the PM leakage flux and by reducing eddy currents on the rotor surface with a special surface shaping. For these new AM rotor concepts, design rules are required for both, electromagnetical and mechanical design. These shall be elaborated in order to care for robust design and easy manufacturability.In the third phase of the project, prototype rotors shall be manufactured by AM and, if required, mechanical or thermal postprocessing. Finally, these rotors will be evaluated by experiment in order to validate the predicted electromagnetical and mechanical properties and operational behaviour, e.g. torque density, efficiency, and torsional strength. In order to demonstrate the benefits of AM for electrical machine manufacturing, comparisons shall be made to conventionally manufactured rotors by simulation as well as by measurement.