Conventional two-coil wireless power transfer (WPT) systems achieve the maximum output power at the optimal distance. In the over-coupled state, in which the distance between coils is shorter than the optimal distance, the input impedance is significantly higher than that with the optimal distance. As a result, the output power at the load is dramatically decreased. In this letter, we propose a method to improve the maximum output power by applying a negative-impedance converter (NIC) to an additional coil. The proposed system can drastically improve the output power at a load even in the over-coupled state because the negative coil eliminates the impedance reflected by mutual coupling between coils. To validate the proposed method, the NIC was implemented with an operational amplifier and four identical coils. In the experiment, the proposed system transferred enhanced power, which was three times higher than the maximum output power of the conventional system.

中文翻译：

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在过耦合 WPT 系统中使用负线圈提高最大输出功率

传统的两线圈无线电力传输 (WPT) 系统可在最佳距离下实现最大输出功率。在过耦合状态下，线圈之间的距离小于最佳距离，输入阻抗明显高于最佳距离。结果，负载处的输出功率显着降低。在这封信中，我们提出了一种通过将负阻抗转换器 (NIC) 应用于附加线圈来提高最大输出功率的方法。即使在过耦合状态下，所提出的系统也可以显着提高负载下的输出功率，因为​​负线圈消除了线圈之间互耦合所反射的阻抗。为了验证所提出的方法，使用运算放大器和四个相同的线圈实现了 NIC。在实验中，