A Reconfigurable Coil grid for Receiver Localization in Wireless Power Transfer and Magnetic Field Steering

The main purpose of Inductive Power Transmission (IPT) is efficient power transfer. Yet the ability to localize the receiver is itself an interesting goal. In Qi standards for wireless power transfer, the localization is performed by using a coils array. The resolution of localization is equal to the diameter of the coils in the transmitter array. Decreasing the diameter of coils in transmitters increases the resolution of localization but also reduces the range of power transfer. IPT is used in inductive RFID (Radio Frequency Identification) where a trade-off between resolution of localization and range of tag detection arises. This paper proposes an original system making it possible to modify the resolution and the distance of operation independently. Calculations and simulations are implemented in MATLAB software. Experiments in low frequency validate the method and show the system capability to localize the receiver with good accuracy, with mean absolute error of 4 mm for localizing a receiver coil of 1 cm radius positioned in a box with dimensions 20*20*10 cm. Transmitter is a grid of 9 coils of 3.3 cm radius. After localization, the magnetic field is steered in the direction of the receiver to obtain a more efficient power transfer.