[论文解读] Wireless Power Transfer for High-precision Position Detection of Railroad Vehicles

Hyun-Gyu Ryu, Dongsoo Har|arXiv (Cornell University)|Aug 31, 2015

Wireless Power Transfer Systems参考文献 4被引用 4

一句话总结

本文提出了一种无线能量传输（WPT）系统，用于在铁轨车辆中实现高精度位置检测，通过在轨枕中嵌入类似RFID的无源标签实现。该系统利用磁感应和铁氧体基磁束整形技术，在列车及轨道结构中的铁磁性材料干扰下仍能提升能量传输效率，仅需读取线圈发射几瓦功率即可实现标签的可靠工作。

ABSTRACT

Detection of vehicle position is critical for successful operation of intelligent transportation system. In case of railroad transportation systems, position information of railroad vehicles can be detected by GPS, track circuits, and so on. In this paper, position detection based on tags onto sleepers of the track is investigated. Position information stored in the tags is read by a reader placed at the bottom of running railroad vehicle. Due to limited capacity of battery or its alternative in the tags, power required for transmission of position information to the reader is harvested by the tags from the power wirelessly transferred from the reader. Basic mechanism in wireless power transfer is magnetic induction and power transfer efficiency according to the relative location of the reader to a tag is discussed with simulation results. Since power transfer efficiency is significantly affected by the ferromagnetic material (steel) at the bottom of the railroad vehicle and the track, magnetic beam shaping by ferrite material is carried out. With the ferrite material for magnetic beam shaping, degradation of power transfer efficiency due to the steel is substantially reduced. Based on the experimental results, successful wireless power transfer to the tag coil is possible when transmitted power from the reader coil is close to a few watts.

研究动机与目标

• 通过嵌入轨枕中的无源标签，实现在铁轨车辆中的高精度位置检测。
• 通过从读取器无线采集能量，解决标签电池寿命有限的问题。
• 缓解列车及轨道结构中钢等铁磁性材料导致的能量传输退化问题。
• 通过铁氧体材料实现磁束整形，优化能量传输效率。
• 通过实际功率水平的实验验证系统的可行性。

提出的方法

• 利用磁感应实现列车上读取线圈与轨枕中嵌入的标签线圈之间的无线能量传输。
• 采用铁氧体材料对磁场进行整形，减少漏磁通及附近钢质部件的干扰。
• 通过仿真分析读取线圈与标签线圈之间相对位置对能量传输效率的影响。
• 设计并测试了原型系统，读取线圈发射功率为几瓦。
• 测量标签线圈接收到的功率，评估在含钢质结构的实际环境下的性能表现。
• 通过实验结果验证系统，证明在实际功率水平下可成功实现能量采集。

实验结果

研究问题

• RQ1 列车及轨道中存在铁磁性材料如何影响无线能量传输效率？
• RQ2 基于铁氧体的磁束整形能否有效缓解钢质部件引起的效率下降？
• RQ3 读取器需要多大功率才能确保系统中无源标签的可靠运行？
• RQ4 读取线圈与标签线圈之间的相对位置如何影响能量传输效率？
• RQ5 无线能量传输是否适用于在真实铁路环境中为无源位置检测标签供电？

主要发现

• 基于铁氧体的磁束整形显著降低了列车及轨道中铁磁性材料引起的能量传输效率退化。
• 当读取器发射几瓦功率时，能量传输效率仍保持足够高，可实现标签的可靠运行。
• 仿真与实验结果共同证实，该系统在真实条件下可实现稳定且充足的无源标签供电。
• 该系统可实现无需更换标签电池的连续、高精度位置检测。
• 实验成功验证了无线能量传输的可行性，证实了该方法在真实铁路应用中的有效性。