Guest Editorial: Advances in High‐Speed Machines for Electric Drives, PowerGeneration and Energy Storage Systems
Guest Editorial: Advances in High‐Speed Machines for Electric Drives, PowerGeneration and Energy Storage Systems
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客座社论：电力驱动、发电和储能系统高速机器的进步
DOI：
10.1049/iet-epa.2018.0189
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发表时间：
2018
影响因子：
1.7
通讯作者：
D. Ionel
中科院分区：
文献类型：
--
作者：
D. Lawhorn;N. Taran;V. Rallabandi;D. Ionel
由于各种因素的影响，高速电机在许多应用领域越来越受到重视。例如，人们通常希望摆脱高速涡轮机或压缩机与耦合电机之间的齿轮箱，而采用直接驱动装置，以获得更高的效率、更高的可靠性和更容易的维护。同时，对于任何给定的额定功率，提高电机的转速是减小其扭矩的有效方法，从而减小其尺寸和重量。这尤其适用于混合动力或电动汽车以及更电动的飞机上使用的电动机和发电机，在这些地方，空间和重量的限制使高功率密度成为一个关键的设计目标。高速电机领域非常广泛，包括各种各样的技术、应用、额定功率和性能要求。在任何情况下，这些机器的设计都是特别微妙的，因为其中的材料和部件受到非常的热、机械和电磁应力，并且往往接近其物理操作极限。例如，高额定频率会导致定子铁心的大磁损耗和定子导体和转子有源部件的涡流损耗，从而可能导致危险的温度；转子表面也可能过热，由于空气摩擦损失在高转速。另一方面，离心力在旋转部件中引起机械应力，导致磨损、疲劳和可能的早期故障。最后，需要达到非常高的速度可能会导致转子暂时越过或接近其临界速度，从而导致整个轴线的可能振动和横向动态不稳定。准确评估所有这些方面对于安全设计是必不可少的，并且由于电磁，热，通风和机械现象之间的密切相互作用，必须采用多物理场方法。由于经常要求最小化机器成本并最大化其功率密度以及其他性能指标，因此设计过程变得更加具有挑战性，从而需要多目标约束优化方法。这意味着需要对成百上千的设计进行比较探索，以寻找最优解，为了使这种广泛的探索可行，需要使用计算效率高的方法来分析每个设计。本特刊收录了13篇同行评审的论文，这些论文提供了一些具体的技术见解，涉及上述关于高速电动机和发电机的设计，分析和运行的一般主题和挑战，用于最先进和新兴的应用。第一篇论文，“在优化算法的帮助下最大化永磁体的功率密度”，由F. Cupertino等人撰写，明确指出了航空用高速表面永磁体功率密度最大化的潜力和限制。它强调，随着额定速度的增长，固定永磁体免受离心力影响所需的保持套厚度也在增长，从而导致更大的气隙，从而限制了功率密度的增加。提出了一个优化过程，包括电磁二维有限元分析（FEA）模拟和分析力学公式，以确定产生最大可实现功率密度的速度。航空用表面永磁电机的功率密度优化也在第二篇论文“航空航天应用中高速无槽永磁同步电机扭矩密度最大化的优化方法”中得到了解决，作者是D. Lee等人。这里的重点是外转子机器拓扑与无槽定子和哈尔巴赫阵列永磁体的安排。优化方法是不同的，因为速度被视为一个约束，连同定子铜损耗，转子机械应力水平，内外机器半径和铁芯长度。通过基于二维有限元的优化，将机器内部尺寸以及哈尔巴赫阵列磁段的磁化方向作为设计变量，以最大限度地提高功率密度。设计优化在第三篇论文“三自由度混合磁轴承的磁路设计和结构优化”中再次被介绍，由Z. Xu等人撰写，但这一次应用于作为许多高速机器关键部件的磁轴承。正确的磁轴承设计，以合适的承载能力和刚度值为目标，是保证高速轴系转子动力学性能的关键。通过磁等效电路技术对磁轴承进行解析建模，加快了粒子群优化过程。最后，通过三维有限元模拟对选定的最优设计进行了详细的研究。第四篇论文“1 kW/ 60000 min - 1无轴承永磁电机与扭矩和转子悬挂组合绕组”中提出了一种创新方法，以实现高速机器中的磁悬浮转子作为传统磁性轴承的替代品。高速电机配有六相定子绕组。利用多相绕组提供的多个自由度，通过传统的磁场定向控制产生转矩，同时产生转子磁悬浮所需的径向力。该解决方案已实现到原型中，并通过各种测试成功验证。Zhang等人的第五篇论文《基于多物理场的高速室内永磁电机设计》阐述了高速电机设计的多学科性质，该论文介绍了高速室内永磁电机的设计过程。强调了多物理场方法的必要性，强调了电磁、结构、转子动力学、传热和流体动力学分析的重要性和相互依赖性，这些分析需要在高速机器的设计中进行。第六篇论文“高速永磁电机转子的转子动力学建模和分析”给出了高速机械设计中转子动力学分析的见解。事实上，预测与转子弯曲模式相关的固有频率（特别是前两个）对于确保所有稳态工作点足够远离临界速度并避免发生危险的振动和机械故障至关重要。C. Babetto等人在第七篇论文“高速同步磁阻电机的设计方法”中讨论了高速同步磁阻电机设计中机械和电磁计算的集成。
High-speed electric machines are gaining more and more importance in several application fields thanks to various factors. For example, it is often desirable to get rid of gear-boxes between high-speed turbines or compressors and the coupled electric machinery in favour of a direct-drive arrangement for better efficiency, higher reliability and easier maintenance. At the same time, raising the speed of the electric machine is an effective way to reduce its torque, and hence its size and weight, for any given power rating. This especially applies to electric motors and generators to be used in hybrid or electric vehicles and in moreelectric aircrafts, where room and weight restrictions make high power density a crucial design target. The field of high-speed electric machinery is very broad encompassing a large variety of technologies, applications, power ratings and performance requirements. In any case, the design of these machines is particularly delicate because materials and components in them are subject to extraordinary thermal, mechanical and electromagnetic stresses and tend to work close to their physical operating limits. For instance, high rated frequencies cause large magnetic losses in the stator core and eddy-current losses in stator conductors and rotor active parts, resulting in possibly dangerous temperatures; rotor surfaces may overheat also due to air friction losses at high rotational speeds. On the other hand, centrifugal forces induce mechanical stresses in rotating components causing wear, fatigue and possible early failures. Finally, the need to reach very high speeds may cause the rotor to temporarily cross or approach its critical speeds, resulting in possible vibrations and lateral dynamic instability of the whole shaft line. Accurately evaluating all of these aspects is mandatory for a safe design and must require a multi-physics approach due to the close interactions among electromagnetic, thermal, ventilation and mechanical phenomena. The design process is made ever more challenging by the frequent requirement to minimise the machine cost and maximise its power density together with other performance indices, leading to the need for a multi-objective constrained optimisation approach. This implies that hundreds or thousands of designs are to be comparatively explored in search for the optimal solutions and, to make such a wide exploration feasible, computationally-efficient methods need to be used for the analysis of each design. This Special Issue features thirteen peer-reviewed papers which provide some specific technical insights into the general topics and challenges mentioned above regarding the design, analysis and operation of high-speed electric motors and generators for state-ofthe-art and emerging applications. The first paper, ‘Maximisation of Power Density in Permanent Magnet Machines with the Aid of Optimisation Algorithms’, by F. Cupertino et al., clearly addresses the potentials and limits of power density maximisation in high-speed surface permanentmagnet machines for aeronautical use. It emphasises how, as the rated speed grows, the retaining sleeve thickness needed to secure the permanent magnet against centrifugal force grows as well, leading to larger air-gaps and thus posing a limit on the power density increase. An optimisation process, including both electromagnetic 2D finite-element analysis (FEA) simulations and analytical mechanical formulas, is proposed to identify the speed that produces the maximum achievable power density. The power density optimisation of a surface-permanent magnet machine for aeronautical use is also addressed in the second paper, ‘Optimisation Method to Maximise Torque Density of High-Speed Slotless Permanent Magnet Synchronous Machine in Aerospace Applications’, by D. Lee et al. Here the focus is on an outer-rotor machine topology with a slotless stator and a Halbach-array permanent-magnet arrangement. The optimisation approach is different as the speed is treated as a constraint, together with stator copper losses, rotor mechanical stress levels, inner and outer machine radii and core length. The internal machine dimensions, as well as the magnetisation directions of Halbach-array magnetic segments, are taken as design variables to maximise the power density through a 2D FEA-based optimisation. Design optimisation is covered again in the third paper, ‘Magnetic Circuit Designing and Structural Optimisation for a Three Degree-of-freedom Hybrid Magnetic Bearing’, by Z. Xu et al., but this time applied to magnetic bearings as a key component of many high-speed machines. A correct magnetic bearing design, targeting suitable load capacity and stiffness values, is essential to guarantee a satisfactory rotor-dynamics behavior of the high-speed shaft line. The magnetic bearing is analytically modeled through the magnetic equivalent circuit technique so as to speed-up the particle-swarm optimisation process. The optimal design finally selected is then investigated in more detail through 3D FEA simulations. An innovative approach to achieve magnetically-suspended rotors in high-speed machines as an alternative to conventional magnetic bearings is presented in the fourth paper, ‘1 kW/60,000 min−1 Bearingless PM Motor with Combined Winding for Torque and Rotor Suspension’, by D. Dietz et al. The high-speed motor is equipped with a six-phase stator winding. The multiple degrees of freedom offered by multiphase windings are exploited to generate the torque through a conventional field-oriented control and, at the same time, to produce the radial force required for rotor magnetic levitation. The solution is implemented into a prototype and successfully validated through various tests. The multi-disciplinary nature of high-speed motor design is illustrated in the fifth paper, ‘Design of High Speed Interior Permanent Magnet Motor Based on Multi-Physics Fields’, by F. Zhang et al., which presents the design process for a high-speed interior permanent-magnet motor. The need for a multi-physics approach is emphasised, stressing the importance and interdependence of the electromagnetic, structural, rotor-dynamics, heat-transfer and fluid-dynamics analyses which need to be performed in the design of a high-speed machine. An insight into the rotor-dynamics analysis in high-speed machine design is given in the sixth paper, ‘Rotor-Dynamics Modelling and Analysis of High-Speed Permanent Magnet Electrical Machine Rotors’, by Z. Huang and Y. Le. Predicting the natural frequencies associated with the rotor bending modes (especially the first two) is, in fact, essential to ensure that all steady-state operating points are sufficiently far from critical speeds and avoid the occurrence of dangerous vibrations and mechanical failures. The integration of mechanical and electromagnetic calculations in the design of high-speed synchronous reluctance motors is addressed in the seventh paper, ‘Design Methodology for HighSpeed Synchronous Reluctance Machines’, by C. Babetto et al.