磁耦合谐振式无线电能传输系统的阻抗匹配方法研究

Research on impedance matching method for magnetic resonant coupling wireless power transmission system

针对磁耦合谐振式无线电能传输系统中传输距离或负载的改变会导致输入阻抗与射频内阻不匹配,引起输出功率下降的问题,以L型匹配网络为例,提出了一种基于Smith圆图理论的阻抗匹配方法。该方法根据等效电路理论和Smith圆图理论推导出了关于匹配电感和匹配电容的参数表达式,在阻抗失配的情况下通过调节归一化电阻变量即可控制匹配网络参数,从而实现系统的阻抗匹配。仿真和实验结果表明,该匹配方法网络结构简单,避免了复杂的计算过程;相同条件下,匹配后的系统输出功率相较匹配前得到了明显提高,且可有效抑制系统的频率分裂。

In view of the problem that the input impedance does not match the RF internal resistance and the output power decreases due to the change of transmission distance or load in magnetic resonant coupling wireless power transmission system,an impedance matching method based on Smith chart theory was proposed taking L-type matching network as an example.Based on equivalent circuit theory and Smith chart theory,a parameter expression of matching inductance and matching capacitance is derived.In the case of impedance mismatch,the matching network parameters can be controlled by adjusting normalized resistance variables,so as to realize the impedance matching of the system.The simulation and experimental results show that the network structure of the matching method is simple and the complex computation process is avoided.Under the same conditions,the output power of the system after matching is significantly improved compared with that before matching,and the frequency splitting of the system can be effectively suppressed.