飞轮用永磁悬浮轴承的磁路设计及磁力解析模型

Magnetic circuit design and magnetic analytical model of permanent magnet suspension bearing for flywheel

飞轮储能以其突出优势广泛应用于电网调频领域,为进一步提升飞轮储能技术的能量密度和功率密度,飞轮储能转子趋向于重型化、高速化,其通常采用磁悬浮轴承进行轴向卸载,而大承载力、高安全性、低损耗能的永磁轴承设计是关键技术。目前研究的双环、多环和Halbach阵列的永磁轴承卸载结构,在长期高速旋转下存在着与转子固联的动磁环材料会出现强度不够的突出问题,因此本文提出一种单环吸力型轴向永磁轴承拓扑结构。以3种拓扑结构中的1种为设计示例,充分利用磁能、节省用材为设计要求,基于基尔霍夫两大定律确定了单环吸力型轴向永磁轴承的结构参数,在考虑边缘磁通效应的影响下,利用磁场分割法对各部分磁通进行了精确划分,建立了等效磁路模型,依据虚位移法推导出了轴向承载力和轴向静刚度的解析计算模型,并采用有限元方法对所建立的解析模型进行了验证,结果吻合良好,为永磁轴承的设计与后续飞轮动力学分析提供了理论依据。

Flywheel energy storage is widely used in the fields of frequency modulation of power grids due to its outstanding advantages.To further improve the energy density and power density of flywheel energy storage technology,the flywheel energy storage rotors tend to be heavy and high-speed,and magnetic suspension bearings are usually used for axial unloading.The key technology is the design of permanent magnetic bearings with a large carrying capacity,high safety,and low energy loss.The permanent magnetic bearing unloading structure of the double-ring,multi-ring,and Halbach arrays currently being studied have the prominent problem of insufficient strength of the moving magnetic ring material fixedly connected with the rotor under long-term high-speed rotation.Therefore,this paper proposes a single-ring suction type axial permanent magnetic bearing topology.Taking one of the three topological structures as a design example,making full use of magnetic energy and saving materials as the design requirements,the structural parameters of the single-ring suction type axial permanent magnetic bearing are determined based on Kirchhoff’s two laws.Under the influence of the flux effect,the magnetic field segmentation method is used to accurately divide the magnetic flux of each part,and the equivalent magnetic circuit model is established.The analytical calculation model of the axial bearing capacity and the axial static stiffness is derived based on the virtual displacement method,and the finite element method is used to verify the established analytical model,and the results are in good agreement,providing a theoretical basis for the design of permanent magnet bearings and subsequent flywheel dynamics analysis.