Active Tuning of Wireless Power Transfer System for compensating coil misalignment and variable load conditions

Abstract Wireless Power Transfer is an alternative technique for powering remote devices across small gaps where the use of cables is not suitable. Such technique requires inductive coupled coils in a tuned circuit in order to efficiently transfer power to a load. Thus, the power transferred to the load is very sensible to variations in the position between the transmitter and receiver coils as well as the variations in the load. This work presents a multi-variable dynamic method for tracking the maximum possible output power in a wireless power transfer system robust to misalignments and load variations. An electronic system, located in the transmitter, monitors the magnitude and phase of the input current of the inductive link while actuating in both the source frequency and a variable matching network executing the tracking algorithm. Experimental results showed that the power delivered to the load, controlled only by the transmitter, can be substantially increased in low values of magnetic coupling coefficient k. Also, the power the can be held approximately constant over a large range of magnetic coupling coefficients and load values. This are significant improvements on the results obtained by actuating only on the source frequency or only on the matching network.