RFID-triggered power activation for smart dynamic inductive wireless power transfer

Abstract

A RFID-triggered power activation system is devised, implemented and tested as the key sensing mechanism for controlling wireless power transfer from an inductive lane to a moving lightweight electric vehicle. The RFID reader and tag used are based on ISO/IEC-14443A compatible types, working at 13.56 MHz, one of the least expensive currently available passive near-field technologies. In order to fit lightweight electric mobility application requirements, the RFID magnetic antennas are redesigned to larger than standard sizes, both at reader and tag sides, increasing the detection volume without increasing the required reading power, thus permitting the reuse of commercial RFID circuits and embedded protocol software. To trigger the wireless power transfer, a RFID reader coil is placed magnetically orthogonal to each primary power coil to be controlled, at the extremity where electric vehicles are expected to come from, in a one-way traffic. The power is turned off automatically when the vehicle leaves the primary coil field and the power demand is extinguished, or when time-out is reached. An inductive lane constituted of a sequence of such RFID-controlled primary coils can detect the presence of authorized electric vehicles and smartly energize the lane, manipulating the unique identifier codes and other information stored in the on-board tag to more efficiently handle dissimilar power level demands, and to implement tolling. The performance of the system is predicted based on the reconstructed 3D digital model of the RFID main detection lobe.