双负载磁谐振S-LCL无线充电系统频率分叉分析

Analysis of Frequency Bifurcation of Dual Load Magnetic Resonance S-LCL Wireless Charging System

磁耦合无线充电系统在过耦合情况下会出现频率分叉现象,从而导致频率谐振点系统性能大幅降低。针对无线充电系统存在的频率分叉现象,目前已有文献大多都基于SS结构等基本拓扑进行研究,而缺少对S-LCL等复杂谐振结构频率分叉现象的研究,因此选择对双负载磁谐振S-LCL无线充电系统的频率分叉进行研究。首先分析了双负载系统输出特性随工作频率的变化情况。然后,利用谐振频率下的阻抗特征推导出双负载系统可以规避频率分叉现象的条件以及分叉谐振频率的表达式。仿真分析了耦合系数与负载阻值对双负载磁谐振S-LCL无线充电系统频率分叉临界点和输出特性的影响,得到了规避频率分叉现象的负载与耦合系数的取值范围。最后,搭建Matlab仿真模型和物理平台对所得结论进行验证。

The frequency bifurcation occurs in the magnetic coupling wireless charging system under the condition of over coupling,which leads to a significant reduction in the system performance of the frequency resonant point.In view of the frequency bifurcation phenomenon in wireless charging system,most of the existing literatures are based on the basic topology such as SS structure,and lack of research on the frequency bifurcation phenomenon of complex resonant structures such as S-LCL.Therefore,the frequency bifurcation of dual-load magnetic resonance S-LCL wireless charging system is studied.Firstly,the variation of output characteristics and system efficiency of dual-load system with operating frequency is analyzed.Secondly,the conditions under which the dual-load system can avoid the frequency bifurcation phenomenon and the expression of the bifurcated resonant frequency are derived by using the impedance characteristics at the resonant frequency.The influence of coupling coefficient and load resistance on the frequency bifurcation critical point and output characteristics of the dual-load magnetic resonance S-LCL wireless charging system is simulated and analyzed,and the value range of the load and coupling coefficient to avoid the frequency bifurcation phenomenon is obtained.Finally,Matlab simulation model and physical platform are built to verify the conclusions obtained.