High Power Density Stacked-Coils Based power Receiver for MHz Wireless Power Transfer

Wireless power transfer (WPT) is desirable for the charging of consumer electronic devices, such as cell-phones. However, the charging power is still low compared to the conventional plug-in charging, which makes the WPT solution less competitive. This paper proposes a high power density stacked-coil based power receiver for MHz WPT applications. The proposed high power density stacked receiving coil can harvest more power with certain magnetic field for the WPT systems. Detailed circuit model of the proposed stacked-coil based power receiver for WPT system is presented and associated compensation methodology is proposed which is independent of the variation of coil coupling and final loads. Both calculation and simulation are used to validate the proposed design and desired performances. Comparison experiments are also designed and implemented to verify the derivation and the analysis of the stacked-coil based power receiver. Experimental results show that stacked-coil based power receiver can harvest more energy and show improved efficiency compared to the conventional single-coil based power receivers.