【作者】 刘敏贤；

【导师】 王素玉；

【作者基本信息】 西南交通大学 ， 电工理论与新技术， 2009， 博士

【摘要】 处于永磁轨道上方的高温超导块材具有自稳定悬浮特性,因此高温超导磁悬浮列车性能相比其他两种的主要磁悬浮列车(常导磁悬浮列车和低温超导磁悬浮列车)具有控制简单、成本低廉及环保节能等优点。高温超导磁悬浮车可能成为将来的一种高速、安全、环保、经济的最有效的地面轨道交通方式之一。本研究小组也在这方面作了大量的研究与探讨,并于2000年底研制成功世界首辆载人高温超导磁悬浮实验车。这种车系统的永磁轨道希望在车运行的方向的磁场保持均匀,但在实际应用中,由于安装工艺等因素的影响,使得其磁场在纵向存在一定的波动。本论文就这种磁场波动对块材悬浮力性能的影响展开工作。永磁轨道由于安装工艺的因素,在永磁块和永磁块之间存在一定的缝隙,该缝隙使得轨道上方的磁场存在一定波动。本论文通过实验测试和计算机仿真计算相结合的方法研究了缝隙对轨道磁场波动的影响。通过坐标变换,把空间周期变化的磁场等效为时间周期变化的磁场,为实验研究波动外磁场作用下,块材悬浮力特性提供了理论基础,并通过永磁轨道的磁场和电磁铁磁场的叠加模拟高温超导磁悬浮车运行时,块材周围的磁场环境。以此来研究波动磁场对悬浮力性能的影响。首先通过实验研究了交流磁场频率对悬浮力性能的影响情况,在实验的基础上,首次将频率对悬浮力的影响划分为三个不同的区域,分别是：低频(悬浮力振荡为主要特征)、高频(悬浮力振荡很小,悬浮力衰减为主要特征)和过渡区域,并实验研究了频率发生变化(包括突变和渐变)时,交流磁场对悬浮力的影响。接着系统地分析了在低频(100 Hz以下)交流磁场下,块材悬浮力振荡和衰减特性,并借助Bean临界态模型阐述了波动外磁场对块材悬浮力影响的作用原理,研究了交流磁场幅值对悬浮力振荡和衰减的影响,研究了不同场冷高度或者测试高度情况下,波动外磁场对悬浮力性能的影响情况。此后研究了高频(170 Hz以上)交流磁场作用下,块材悬浮力的衰减特性,包括交流磁场的幅值和频率对悬浮力衰减的影响,同样也研究了不同场冷高度和不同测试高度情况下,波动外磁场对悬浮力性能的衰减影响情况。考虑到高温超导磁悬浮车的实际运行情况,论文中还研究交流磁场作用时间对悬浮力性能的影响。在Bean临界态模型的基础上,针对目前的高温超导磁悬浮车系统,提出了一种通过磁场在块材中的穿透情况来计算块材悬浮力的模拟计算方法。该方法可计算在波动外磁场中块材悬浮力的振荡和衰减情况。通过实验结果与模拟计算结果的对比,验证了该方法的可行性。通过该方法讨论了高温超导块材的性能(临界电流密度、块材尺寸)对波动外磁场中高温超导块材悬浮力的影响情况。更多还原

【Abstract】 The high temperature superconductor (HTSC) bulk can realize inherently self-stable levitation in external magnetic field without any active control, so the high temperature superconducting magnetic levitation (Maglev) train is more significant potential for the maglev train than the normal electromagnets maglev and the low Tc superconducting maglev. The superconductivity maglev train will be one of the transports with high-speed, safety, reliability, low environmental impact. Our group did a lot of research on high temperature superconductivting (HTS) maglev vehicle system and successfully developed the first man-loading HTS maglev test vehicle on Dec.31,2000. For the HTS maglev vehicle system, it required that the magnetic field is i mmutable along the lengthways direction. However, the permanent magnet guideway (PMG) is composed many permanent magnets, there should be air gap between the adjacent magnets, which would fluctuate magnetic field above the PMg surface. So the present thesis considers the effect of the fluctuant magnetic field on the levitation force of the HTS bulk above the PMG.For the permanent magnet guideway of the HTS Maglev vehicle system, there should be some air gaps between two adjacent permanent magnets by connecting, which may generate ripple magnetic field in the forward direction of the vehicle. The surface magnetic field of the PMG is measured and simulated by a computer. From the experimental and the simulation results, the influence of the air gap on the magnetic field above PMG is investigated.For the Maglev vehicle engineering application, we investigate the levitation force characteristics of the HTS bulk above the PMG exposed to the AC magnetic field generated by electromagnet, which is used to simulate the possible fluctuation of the PMG.Firstly, the influence of the AC field frequencies on the levitation force is investigated, according to characteristic of the levitation of HTS bulk expose the AC field above PMG., it is the first time to divide the frequencies into low-frequency, high-frequency and transition-frequency. Besides, the influence of variation of frequency of the AC field on the levitation force is investigated. Then, the oscillation and attenuation characteristic of the levitation force of the HTS bulk expose to the low-frequency AC field are investigated; based on the Bean critical model, we explained the oscillation and attenuation of the levitation force and discussed the influence of amplitude of AC field on the levitation force. We also compare the levitation fore oscillation and attenuation of the bulk exposed to the fluctuant external magnetic field under the conditions of different field-cooled height or different work height. Similarly, the characteristic of the levitation force of the HTS bulk expose to the high-frequency AC field is also investigated.Based on the Bean critical model, a simulation method is adopted to calculate the oscillation and decay of levitation force of the bulk exposed to. fluctuant magnetic field for the current HTS maglev system. Compared the experimental results with the simulation ones, it was found that the simulation method was feasibility and could qualitatively reveal the characteristics of levitation force of HTS bulk in this situation. Furthermore, the influences of. critical current density and the dimension of a superconductor on the levitation force of the bulk exposed to fluctuant magnetic field are investigated by the simulation method.更多还原