中文摘要：

为了解决近距离传输时无线能量传输系统出现频率分裂导致多个功率极值点的问题，建立了系统的传输模型。综合考虑谐振频率、负载大小、两线圈间的耦合强度等参数，探讨了频率分裂现象发生的内在因素和边界条件。结果表明：在负载大小不变的情况下自然谐振频率越高，越容易发生频率分裂，当频率分裂现象发生时，系统的最大传输功率将不在线圈的自然谐振频率处，给系统稳定性及功率优化控制带来了困难。为此提出了一种近距离传输时通过降低谐振频率来解决频率分裂的方法，当传输距离减小时降低系统的谐振频率可使系统成功退出频率分裂区域，并在负载不变的情况下传输功率可提高400％，而传输效率仅下降约14％，极大地提高了系统的传输性能。

英文摘要：

In order to solve the multiple power extreme value point problem caused by system frequency splitting during wireless energy transmission at short distances a transmission model of the system is established.With the comprehensive consideration of the resonance frequency load parameters and the coupling between coils the internal factors of frequency splitting and boundary conditions are discussed.The results show that under the condition of the fixed load the higher the natural resonance frequency the easier the frequency splitting. As the frequency splitting occurs the frequency of the maximum power transfer is no longer with the natural resonance frequency which can make the system unstable and the transfer power more difficult to control. Therefore a decreasing-frequency method is proposed to avoid the system frequency splitting. And decreasing the system resonance frequency can make the system successfully withdraw the frequency splitting area at a short-distance range.Under the fixed load condition the transmission power of the system can be increased by 400% and the transmission efficiency is reduced by only 14% which greatly improves the transmission performance of the system.