Single-Core Dual Coils in Wireless Power Transfer Systems with Force-Display Functions

Conventional wireless power transfer technologies primarily focus on wireless charging devices, overlooking the impact of mechanical connections, such as cable tension on user interfaces. In contrast, we are exploring a wireless power transfer system with force-display functions to enable users to intuitively perceive the power supply status of electronic devices. The system used a permanent magnet on the receiver side and an electromagnet on the transmitter side. The charging status of the electronic device can be intuitively displayed to the user by adjusting the electromagnet based on the circumstances. In this paper, we present the design and implementation of single-core dual coils that realize both electromagnetic and wireless power transfer coils in a single core. Through experimental evaluations, the generation of attractive and repulsive forces up to approximately 2 N was confirmed in terms of the electromagnetic force. In addition, the maximum power transfer efficiency reached 87%.