功率和效率是电能传输系统的两个重要指标，利用理论分析结合实验研究的方法，探讨磁共振耦合无线电能传输系统的功率和效率传输特性。分析指出负载功率与系统效率频率响应曲线均存在分叉现象，收发端参数相同的传输系统的负载功率频率响应曲线呈近似对称形状，分叉现象消失前的负载功率不随收发端距离的变化而变化；参数非对称系统频率分叉时存在主从共振频率之分，且负载功率会随收发端距离的增大先增大后减小。理论推导出系统临界耦合系数及功率最优传输条件下的收发端优化耦合系数数学表达式。针对峰值功率与峰值效率工作频率点不重合的特性，提出了基于信息反馈的能效优化控制策略，借助能量传输通道，利用负载调制技术将接收端工作状态向发送端实时反馈，实现能量传输过程的闭环控制。文中理论分析结论与实验结果相一致。%Power and efficiency are two important indexes for power transmission systems.By theoretical analysis combined with experiments,the transmission characteristics of power and efficiency for the wireless power transmission system based on magnetic resonance coupling are researched.The results show that there is the bifurcating phenomenon in both the bearing power and the frequency response curves of system efficiency.The bearing power and frequency response curves of a transmitting system with identical parameters at the transmitting and receiving terminals appear to be approximately symmetric in shape.The bearing power before bifurcation vanishes does not vary with the change in distance between transmitting and receiving terminals.There is the difference between the primary and secondary resonance frequencies when the frequency is bifurcated for asymmetrical systems,and the bearing power will be enhanced first and then declined with an increase in the transmission distance.Mathematical expressions for critical coupling coefficient and transmitting and receiving terminals optimization coupling coefficient for optimal power transmission are deduced.In view of the feature that the peak power and peak efficiency working frequency points do not coincide,an information feedback-based energy efficiency optimal control strategy is proposed.In addition,by the aid of the energy transmitting channel,the work state is fed back to the transmitting terminal using the load modulating technique to realize closed loop control of the energy transmission process.The conclusions drawn in the paper are in agreement with experimental results.
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