High-efficiency self-resonant transmitters and receivers for wireless power transfer

无线电力传输具有新兴和潜在的应用，例如为个人电子产品和电动汽车充电，以及为无线传感器供电。然而，目前，在距离和效率方面的能力是有限的。这项工作将开发一种新的自谐振结构，以取代目前使用的发射和接收线圈，并使距离和效率得到改善。该结构可以使用低成本无毒的可回收材料制造，并且可以在广泛的功率水平，频率和尺寸范围内进行扩展。这种新方法提高了效率，可以在最小的效率损失下从传统的有线连接迁移到无线电源传输，同时无线电源的扩大使用可以促进低成本传感器网络和电动汽车等有益的新技术。用于发射和接收无线电源的谐振电路的质量因子Q是决定可达到的距离和效率的重要指标。本工作中开发的新型谐振结构有望实现更高的Q，从而实现更远的距离和更高的效率功率传输。除了应用于无线电力传输之外，这项工作中开发的方法可能会导致更有效的谐振结构，适用于更传统的电力和能源应用。将发展共振结构的两种几何形状。平面版本使用由薄聚合物介电层分隔的薄箔导体堆叠。每个箔都比蒙皮深度薄得多，从而克服了蒙皮效应损失。箔层之间的电容在工作频率下与电流回路的电感共振，这样主要的大电流路径完全在线圈内，不需要在线圈外建立大电流连接，也不需要外部谐振电容器。由层形成的电容器也充当镇流器阻抗，以实现层之间的相等电流共享，这是更传统的层箔绕组的关键和困难的挑战。平面技术与磁芯配合使用效果最好，磁芯可以形成磁场，以实现发射器和接收器之间最有效的耦合，并通过使磁场与箔层平行来最大限度地减少损耗。对于频率更高的应用，软磁材料性能不那么好，在环形基板上多步骤沉积的类似结构将被用来实现相同的优势，而不需要磁芯。

Wireless power transfer has emerging and potential applications such as charging personal electronics and electric vehicles, and powering wireless sensors. However, at present, the capabilities in terms of distance and efficiency are limited. This work will develop a new self-resonant structure to replace the transmit and receive coils now used, and enable improvements in distance and efficiency. The structure can be fabricated using low-cost non-toxic recyclable materials, and is scalable for a wide range of power levels, frequencies and sizes. The increased efficiency of this new approach can allow migration from conventional wired connections to wireless power transfer with minimal loss of efficiency, while expanded use of wireless power can facilitate beneficial new technologies such as low-cost sensor networks and electric vehicles. The quality factor Q of the resonant circuits used for transmitting and receiving wireless power is an essential figure of merit that determines the achievable distance and efficiency. The new resonant structures developed in this work are expected to achieve higher Q and therefore make longer distance and higher efficiency power transfer feasible. Beyond the application to wireless power transfer, the approach developed in this work may lead to more efficient resonant structures applicable to more conventional power and energy applications.Two geometries of the resonant structure will be developed. A planar version uses a stack of thin foil conductors separated by thin polymer dielectric layers. Each foil is much thinner than a skin depth, thereby overcoming skin-effect losses. The capacitance between the foil layers resonates with the inductance of the current loop at the frequency of operation, such that the main high-current path is completely within the coil, eliminating the need for high-current connections exiting the coil, as well as eliminating the need for external resonant capacitors. The capacitors formed by the layers also act as ballast impedance in order to achieve equal current sharing between layers, a critical and difficult challenge in more conventional layered-foil windings. The planar technology works best in conjunction with a magnetic core that shapes the field to achieve the most effective coupling between the transmitter and receiver, and to minimize losses by making the field parallel to the foil layers. For higher frequency applications, where soft magnetic material performance is not as good, similar structures deposited in multiple steps on a toroidal substrate will be used to effect the same advantages without the need for a magnetic core.