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

创新点：该概念的新颖性包括将轴向主动磁轴承供电集成到无轴承电机的逆变馈电中，以降低系统成本。特别是，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。这为轴向磁轴承提供动力。项目内容：该概念在1 kW / 60000 rpm的无轴承驱动器上实现，以研究其运行限制。关键的影响是确定和深入研究。原型是（参数化）设计、制造和测量的。这个概念也适用于模拟中的更高功率类，以便确定大小的影响。比较了不同的动力等级和与传统馈电原型。准备工作：在原理和仿真上证明了新概念的可行性。一些电机和逆变器约束，伴随零序电流，已定性导出。此外，还从理论上讨论了转子永磁体涡流的扰动力。有了这一初步工作，该项目的成功与研究成果是现实的。项目目标：为了深刻认识到该概念的应用范围限制，一个基本的设计方法，包括可扩展性，以及在实践中的实现是必不可少的。只有在理论上解释了实际认识之后，才有可能对概念进行最后的验证。本项目正是填补了这一空白，即对运行极限的理论和实践研究。具体来说，回答了以下问题：a)增大零序电流和更高功率等级时，转矩和悬架力脉动如何变化？b)当零序电流增大和功率等级增大时，电机内部的损耗组成是如何变化的？c)逆变器开关频率对轴向位置控制的动态影响有多大，对于更高功率等级的igbt逆变器可以得出哪些结论？d)为了保证轴向位置控制的足够动态，逆变器必须提供多少电压储备？e)哪种绕组拓扑结构适用于零序电流馈电的无轴承电机？f)为了补偿涡流效应引起的扰动力，径向位置控制的刚度应该增加到什么程度？对于系统控制可以得出哪些结论？g)大型永磁材料的电导率是什么，不适合用于无轴承机器，这是否适用于更高的功率等级？

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?