高温超导-永磁混合悬浮车基本系统的理论模型与实验

Theoretical model and experiment of the hybrid Maglev vehicle employing high temperature superconducting magnetic levitation and permanent magnetic levitation

具有磁通钉扎特性的高温超导磁悬浮是自然界唯一一种悬浮导向一体化自稳定悬浮系统,但其载重能力相对较弱;永磁体斥力式的永磁悬浮具有结构简单、载重能力强的优点,但在横向上不稳定.针对两种磁悬浮技术特征,基于现有的高温超导磁悬浮环形实验线"Super-Maglev",本研究以实现高温超导磁悬浮实验车大载重为目标,提出了一种新型的高温超导-永磁混合悬浮车系统概念及理论设计方法.首先,通过分别对永磁悬浮模块和超导导向模块建立在同一磁轨条件下的电磁模型,仿真对比分析两模块的磁力特性发现,两模块在垂向上的悬浮工作区间差异明显,在横向上具有相反的横向刚度.其次,结合恩肖定理,预测了混合悬浮系统在横向稳定条件下的最大载重能力及稳定工作区间.最后,基于仿真结论和现有的高温超导磁悬浮实验车,设计选用具有垂向解耦横向刚接功能的垂向直线轴承连接两悬浮装置,始终保持两模块在垂向上独立运动及横向上刚性连接,实现车载永磁载重与超导导向的功能匹配互补,搭建了高温超导-永磁混合悬浮原理实验样车,可载一人安全运行.进一步的准静态力学及动态振动实验共同验证了混合悬浮原理实验车具有成本低、结构简单、无源自稳定等优点,在载重能力提升上有一定的优势.该工作为超导磁浮轨道交通应用提供了新的技术途径.

The Maglev vehicle,widely considered as a promising transportation type,has distinct characteristics,such as high speed,environmental protection,non-contact operation and distributed load and so on.According to the principle of magnetic levitation technology,it can be divided into four types:Permanent magnet levitation(PML),electromagnetic levitation(EML),electrodynamic levitation(EDL)and superconducting magnetic levitation(SML).Among four Maglev technologies,both the SML with high temperature superconducting(HTS)bulks and the PML with conventional permanent magnets belong to the passive levitation mechanisms,and both of them need permanent magnet track.Due to the strong magnetic properties of permanent magnet materials,the load capacity of the PML can reach 3-6 t/m,but requires additional guidance controls,while the SML with the unique HTS flux-pinning effect can realize self-stable levitation with little active control.Therefore,considering the different levitation characteristics of the SML and the PML above the permanent magnet track,their potential hybrid application can achieve a larger load capacity and a bigger levitation gap at the same time.In the paper,a new SML-PML hybrid Maglev method and the corresponding theoretical models are proposed.Firstly,simulation models of the PML module and the SML module were built by finite element software.The simulation results show the different levitation performances of the two Maglev components.As to the SML module,it vertically behaves as the levitation force within the levitation height of 10-15 mm,and always achieves passive stable along the lateral direction.As to the PML module,the levitation force is relatively bigger at the calculated height of 20-60 mm,but the lateral force increases as the levitation height decrease and increases with the lateral displacement.It implies that the SML guidance capability should cover the PML lateral force at first.Hence,according to the Earnshaw theorem,the load capacity in typical working cases of the hybrid Maglev system was predicted from the simulation data.Considering the further lateral stability and the comprehensive levitation force utilization,the optimal passive stable working range and the lateral reversible range were discussed,which provide the theoretical basis for the design of the hybrid Maglev vehicle prototype.Then,based on the real magnet tracks of the HTS Maglev ring test line,the"Super-Maglev",in our group,a new manned hybrid Maglev vehicle prototype employing the PML and the SML modules was manufactured for carrying one passenger.In the designed two-layer Maglev frame,the linear bearings composed of the linear guide rails and the sliders are employed for vertical decoupling to guarantee the position difference of the SML and PML modules.At the same time,the lateral coupling keeps rigid since the lateral unbalance is covered by the SML module.This easy and feasible mechanical coupling way enhances the matching complementarity of the lateral recoverability of the two Maglev components.Compared with the"Super-Maglev"performance under the same working condition,the load capacity of the hybrid Maglev vehicle was increased by 17%and the cost input was lower compared with the price of one single on-board HTS bulk.Finally,static loading experiments and dynamic characteristics tests verified that the hybrid Maglev vehicle has the advantages of strong load capacity,simple structure and low cost.This work provides a new technical scheme for future Maglev transportation applications.