Analysis and design of resonant inductively coupled circuits : application to benefit denial solutions for the retail industry

Abstract

ProTeqt develops benefit denial solutions that are electromagnetically deactivated. A magnetic field from the deactivation tablet inductively heats an enabler that provides the proper force to disengage the locking mechanism. Its latest design was not functional at one inch above the deactivation tablet, because of significant efficiency losses in the electromagnetic energy transfer. This is problematic when the product's package is thick. In order to improve the maximal functional distance, an LC circuit is inserted inside the locking device. This thesis describes the optimization and integration of the circuit, used as a weakly coupled electromagnetic resonator in wireless energy transfer. The most efficient resonator design is proposed, under the inherent constraints of this application. It is then tested in real situation in order to evaluate the failure rate of the complete device. Some modifications of the enabler are proposed and discussed to maximize the reliability. Finally, a simulation is conducted to test the sensitivity of the results to the circuit manufacturing variability. Under several clearly stated assumptions, it appears that the manufacturing variability of the hand-made enabler is the most significant, although it does not threaten the reliability of the current locking mechanism.