A Real-Time Tracking Algorithm for 3D Wireless Maximum Power Transfer to a Moving Device

Many personal mobile consumer electronics, such as mobile phones, smartwatches and tablets, require three-dimensional wireless charging due to increased flexibility. However, it is very challenging to transfer power to moving devices in a 3D space. The main problems are the transfer distance and efficiency. This paper proposes a real-time algorithm for tracking maximum power when the device is moving in 3D space, which can considerably improve the transfer distance and efficiency could be improved as much as possible by the proposed algorithm under the same hardware condition. By measuring the input power of the wireless power transfer system and monitoring its gradient change, the minimum value of the cost function is dynamically found, and the maximum power transfer is achieved for a moving device without the need to know its position and pose. Plus, communication between the transmitting and receiving coils is avoided. The correctness and convergence of the proposed algorithm are proven by using LaSalle's invariance principle.