A Multi-Receiver MHz WPT System with Hybrid Coupler

The megahertz (MHz) operating frequency increases the spatial freedom, making it more suitable for multi-receiver wireless power transfer (WPT) scenarios. Generally, in a single-receiver WPT system, similar shapes (e.g. spiral) of the transmitting coil and the receiving coil help to improve the cross coupling. However, in multi-receiver cases, traditional spiral receiving coils limit the maximum number of receivers, and the coil coupling varies obviously as position changes. This paper proposes a hybrid coupler of a spiral transmitting (Tx) coil and solenoid receiving (Rx) coils, which can effectively increase the upper limit of the number of receivers, and is also suitable for some receivers with special shapes (e.g. tubular). In addition, a new design method for the impedance matching network (IMN) of MHz WPT systems, which improves the robustness of the systems when the number of receivers varies, is also proposed.