非铁磁性金属影响下的磁共振耦合电能传输系统建模与分析

摘要

磁共振耦合无线电能传输通道周围存在非铁磁性金属物体时，交变磁场与金属导体相互作用，传输性能受到影响。针对该问题，文中建立了金属物体影响下的非接触电能传输系统模型，推导出任意状态下的功率、效率计算式。理论分析结合实验手段研究金属物体对系统传输性能的影响规律，结果表明：非铁磁性金属物体影响下的共振系统包含无金属干扰系统所具有的共振频率分叉、功率与效率最佳工作频率点往往不重合等基本特性，另外，金属物体的存在还会引起原系统共振频率向上偏移，且传输通道周围的金属物体并不一定总是对系统传输性能产生负面影响，在收发端弱耦合条件下可能对功率或效率传输起到改善作用。分析指出造成系统传输性能变化的根本原因是电涡流参数引起驱动源激励下的系统总等效阻抗及等效负载阻抗的变化所致。理论分析结论与实验结果相吻合。%When there are non-ferromagnetic metal objects around the power transmission channel of magnetic resonance coupling wireless power transmission systems,the power transmission performance will be affected by the interaction of the alternating magnetic field with metal objects.For this problem,a non-contact power transmission system model considering the influence of metal objects is developed,and mathematical expressions of transmission power and efficiency in an arbitrary status are deduced.The influence laws of metal objects on the transmission performance are analyzed by means of theoretical analysis and experiment.The results show that resonance systems influenced by non-ferromagnetic metal objects contain the basic characteristics of what an ideal system has,such as resonance frequency splitting,the optimum operating frequencies of power or efficiency often are not the same.Furthermore,the presence of metal objects can also cause resonance frequency shifting upward relative to the original system,and metal objects around the transmission channel do not always have a negative impact on the transmission performance,for it may benefit the transmission power or efficiency in the weak coupling condition. Theoretical analysis indicates that the root cause of the transmission performance change is that the eddy current parameters will result in variations in the system equivalent parameters,including equivalent impedance of system and load.Experimental results are in good agreement with the theoretical analysis conclusions.