A Simple Method to Determine the Performance of Two-Coil Wireless Power Transfer Systems without Direct Output Measurement

Two-coil wireless power transfer (WPT) systems are composed of two circuits tuned at the same resonance frequency, one containing the source, and other containing the load, both connected to each other by the mutual inductance. The power delivered to the load circuit (Po) divided by the total power supplied by the source (PT) and by the maximum ideal amount of power which can be delivered to the load circuit are usual figures of merit known as efficiency (n) and power transfer capability (P*), respectively. Additionally, it can be defined a third figure of merit (I*) as the power dissipated at the source circuit divided by PT. It has been recently demonstrated that n and P* are related to I* . In this paper, it is presented a simple method to monitor I*, allowing consequently the determination of n and/or P* without any direct measurement at the load circuit. The qualities and limitations of the proposed method are discussed in details. Practical results are included to verify the proposal.