In magnetic resonant wireless power transfer (WPT), relays are placed between a transmitter and a receiver as a means of increasing both the operating distance and the power transfer efficiency, but this makes the analysis of the WPT system more complicated. In this letter, we derive a mathematical expression for the power transfer efficiency with an optimal load resistance based on an equivalent circuit model, and analyze the effects of varying the number of relays on the power transfer efficiency that can be achieved. By means of circuit-level simulations and experiments under a variety of scenarios, we verify the accuracy of our analysis, and we also confirm that there is an optimal number of relays for maximizing the achievable power transfer efficiency for a given end-to-end distance.

中文翻译：

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继电器数量对可实现的磁共振无线电能传输效率的影响

在磁谐振无线电力传输 (WPT) 中，将继电器放置在发射器和接收器之间，以增加操作距离和电力传输效率，但这使得 WPT 系统的分析变得更加复杂。在这封信中，我们基于等效电路模型推导出具有最佳负载电阻的功率传输效率的数学表达式，并分析了改变继电器数量对可实现的功率传输效率的影响。通过各种场景下的电路级仿真和实验，我们验证了我们分析的准确性，并且我们还确认了对于给定的端到端的最大化可实现的功率传输效率存在最佳继电器数量距离。