Design and control of a bearingless permanent magnet synchronous machine with a combined double-three-phase winding for torque and lateral force generation and star point-connected axial active magnetic bearing

创新之处：该概念的新颖性包括将轴向主动磁轴承电源集成到无轴承电机的逆变器馈电中，以降低系统成本。具体地说，轴向主动磁轴承连接在无轴承电机定子绕组的两个星点之间，由零序电流馈电。项目内容：在一台1kW/60000转/分的无轴承传动上实现这一概念，以研究其运行极限。对关键影响进行了识别和深入调查。原型是(参数)设计、建造和测量的。这一概念也被应用到更高功率等级的仿真中，以识别尺寸效应。对不同功率等级和常规馈电样机进行了比较。准备工作：从原理和仿真两个方面证明了新概念的可行性。定性地推导了伴随零序电流的一些电机和逆变器的约束条件。此外，还从理论上讨论了转子永磁体中涡流的干扰力。有了这项前期工作，项目在研究结果方面的成功是现实的。项目的目的：对于概念的应用范围的深刻认识，包括可伸缩性在内的基本设计方法和在实践中的实现是必不可少的。只有在理论上解释了实践认识之后，才有可能对这一概念进行最终验证。该项目正好填补了这一空白，即对运行极限进行了理论和实践研究。特别是，回答了以下问题：a)随着零序电流的增加和较高功率等级，转矩和悬浮力纹波是如何变化的？b)零序电流增加和较高功率等级时电机内部的损耗构成是如何变化的？c)逆变器开关频率对轴向位置控制的动态影响有多大，对于较高功率等级的IGBT逆变器可以得出什么结论？d)必须在逆变器中提供多少电压储备才能实现足够的轴向位置控制动态？e)哪些绕组拓扑适合于零序无轴承电机电流馈送？f)为了补偿涡流效应引起的干扰力，径向位置控制的刚度增加到了什么程度？系统控制可以得出什么结论？g)从哪些导电性是不适合无轴承电机的大块永磁体材料，以及这是否可以扩展到更高的功率等级？

The innovation:The novelty of the concept includes the integration of the axial active magnetic bearing supply into the inverter feeding of the bearingless motor for the sake of system cost reduction. In particular, the axial active magnetic bearing is connected between the two star-points of the bearingless motor stator winding, which is fed by a zero-sequence current. This feeds the axial magnetic bearing.Content of the project:The concept is realized on a 1 kW / 60000 rpm bearingless drive in order to investigate its operation limits. Critical influences are dentified and profoundly investigated. The prototype is (parametrically) designed, built and measured. The concept is also applied to higher power classes in simulation in oder to identify sizing effects. Comparisons between different power classes and with conventionally fed prototypes are made.Preparing work:The feasibility of the novel concept has been shown in principle and simulation. Some of the motor and inverter constraints, accompannied with the zero-sequence current, have been derived qualitatively. Moreover, the disturbing force due to eddy currents in the permanent magnets of the rotor have been discussed in theory. With this preliminary work the success of the project with regards to the research results is realistic.Aim of the project:For profound recognitions regarding limits of the application range for the concept, a fundamental design methodology, including scalability, and the realization in practice is essential. Only after explaining the practical recognitions in theory, a final validation of the concept is possible. This project closes exactly this gap, i.e. theoretical and practical investigation of the operation limits. In particular, the following questions are answered:a) How does the torque and suspension force ripple change for increased zero-sequence current and at higher power classes?b) How does the composition of losses change within the motor for increased zero-sequence current and at higher power classes?c) How much does the inverter switching frequency influence the dynamic of the axial position control and which conclusions can be drawn for IGBT-inverters of higher power classes?d) How much voltage reserve must be provided in the inverter for sufficient dynamic of the axial position control?e) Which winding topologies are suitable for bearingless motors with zero-sequence current feeding?f) To which extent has the stiffness of the radial position control to be increased in order to compensate for disturbing forces due to eddy current effects and which conclusions can be drawn for system control?g) From which electrical conductivity are massive permanent magnet materials inappropriate for bearingless machines and is this scalable for higher power classes?