兰州大学机构库 >土木工程与力学学院
高温超导悬浮系统在场冷条件下的磁刚度研究
Alternative TitleStudy on Magnetic Stiffness of High-Tc Superconducting Levitation Systems under Field Cooling Conditions
赵宪锋
Thesis Advisor周又和
2015-11-26
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword高温超导悬浮系统 场冷 磁刚度 极限拟合法 穿透深度
Abstract针对与磁刚度密切相关的超导磁悬浮力,博士论文首先基于电流和磁场相关联的Kim临界态模型和Maxwell方程组,考虑超导体内部临界电流密度与磁场的函数关系,以屏蔽电流穿透深度为基本变量,建立了隐含屏蔽电流穿透深度的半解析微分方程。采用迭代法进行数值求解,得到了与实验结果吻合的磁悬浮力结果,验证了理论模型的有效性。进而分析了近场冷却情况下,超导磁悬浮力的典型特征,给出了超导磁悬浮力随系统物理参数与几何参数的变化规律。 博士论文针对传统的磁刚度认知程度和实验处理方法,建立了与实际更为符合的磁刚度数据处理方法—极限拟合法。以此方法为基础,讨论了近场冷却情况下,高温超导悬浮系统的磁刚度特征。进一步地详细分析了磁刚度对系统参数的依赖关系,通过对超导体内部屏蔽电流穿透情况和内磁场变化情况进行分析,对磁刚度的变化规律给予了合理解释。博士论文研究了先上升-后下降和先下降-后上升两类典型初始场冷条件的区别。详细讨论了这两种场冷情况下高温超导悬浮系统的磁刚度特征,重点关注了场冷高度对两类情况下系统磁刚度的比对结果。给出了在先下降-后上升场冷条件下磁刚度随临界电流密度、外加磁场、超导体厚度等参数的变化规律。此外,基于屏蔽电流穿透深度理论,对高温超导悬浮系统的实时控制策略提出一些初步构想。基于Kim电磁本构关系、Ampère环路定律,数值求解了悬浮体的动力学微分方程,得到了系统的时间响应曲线以及超导体内部多层电流的穿透特征廓线。讨论了动力系统的角频率和动磁刚度的时变性特征,指出动磁刚度随时间的变化规律符合Logistic函数关系。研究了场冷高度的影响,给出了动磁刚度随场冷高度的增加呈负指数关系减小的规律。从角频率和单位位移增量两个角度分别获得了动磁刚度的结果,进行了对比分析,给出了两种方法差异性的合理解释。进一步讨论了系统的磁阻尼性质,讨论了相对阻尼系数随时间、场冷高度的变化规律。给出了动磁刚度随临界电流密度常数呈负指数关系减小的性质,从超导体的钉扎能力角度进行合理解释。
Other AbstractIn this Ph.D. thesis the characteristics of magnetic stiffness of high-Tc superconducting system under two kinds of field cooling conditions are investigated. A few of new relations between magnetic stiffness and the parameters of HTS are found, using the internal current penetration and magnetic field in superconducting bulk, and the results are explained. Based on Kim critical model and Maxwell equations, a semi analytical implicit equation on shielding currents penentration in bulk is presented. The relation between shielding currents and magnetic field is considered in this equation. The chacteristics of magnetic levitation force is showed based on the solution of the equation. Furtherly, the rule on the levitation force including the parameters of HTS are discussed. Based on the limited-fitting method, the chacteristics of HTS under ascending-descending field cooling condition are showed. The dependences of magnetic stiffness on the parameters of HTS are researched in detail, which can be explained with the change of shielding currents and internal magnetic field.The physical difference between descending-ascending (DA) field cooling condition and ascending-descending one (AD) is provided. We pay more attention to the mechanics behavior of magnetic stiffness of HTS under DA condition and AD one, such as the influence of field cooling heiths. The dependences of magnetic stiffness on critical currents、applied magnet field and thickness etc of HTS are presented. In addition, a preliminary idea about instant cotrolling on high temperature superconducting levitation system is showed considering penetration of shielding currents.Finally, the dynamic characteristics such as angular frequency、dynamical magnetic stiffness and relative damping factor are discussed. The dynamical differential equation is solved using the fourth-order Runge-Kutta method based on Kim critical electro-magnetic model and Ampère circular law. The angular frequency and the dynamical magnetic stiffness are found to be changed with time. The Logistic relation is employed to associate the dynamical magnetic stiffness changing with time. The dependence of dynamical magnetic stiffness on field cooling height is investigated. The relative damping factor of high-Tc superconducting system changes with time and field cooling heights. The effect of crtical current density constant intior of HTS on the dynamical magnetic stiffness is given in this thesis.
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226409
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
赵宪锋. 高温超导悬浮系统在场冷条件下的磁刚度研究[D]. 兰州. 兰州大学,2015.
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