Resonant magnetic coupling (RMC) wireless power transmission (WPT) systems heavily rely on the accuracy of the resonant frequencies of the TX and RX sides to provide longer transmission distances, high power transfer efficiency (PTE) and maximal transferred power (MTP). 
This patent provides a method to calibrate both sides’ resonant frequencies of the RMC WPT system so as to address significant performance degradation of the system due to the intrinsic variations of the inductances of the coils and the capacitances of the resonant capacitors (C1/C2). 
The calibration method detects the voltage drops across the resonant capacitors or inductors and tunes the resonant capacitors accordingly to make the voltage drops maximal. It first calibrates C1 by one of several means and then calibrates C2 with the calibrated C1. The resulted C2 achieves the optimal PTE. After that, C1 is recalibrated in background with the resulted optimal C2 to achieve the highest MTP.

Resonant magnetic coupling (RMC) wireless power transmission (WPT) can more efficiently transmit power at a longer distance without perfectly aligned coils in theory. However, it can achieve its optimal performance only when the inductor-capacitor resonant frequencies of both TX and RX are well controlled at the theoretical values.
This patent provides a method to calibrate both resonant frequencies of the power transmitter and receiver sides of the RMC WPT system. The calibration method detects the voltages across the resonant capacitors or those across the coils to tune the resonant frequencies accordingly. By following the proposed calibration flow, the RMC WPT system can achieve its optimal power transfer efficiency and the maximal transferred power after calibration.

Resonant magnetic coupling (RMC) wireless power transmission (WPT) has the advantages of longer transmission distances, contactless, water- and dust-proof, and excellent user experiences. Hence, it becomes a promising power supply of various electric appliances such as cell phones, implanted biomedical devices, and electric vehicles. This patent provides a method to calibrate both the resonant frequencies of the power transmitter and receiver sides of the RMC WPT system so as to address significant performance degradation of the system due to the intrinsic variations of the inductances of the coils and the capacitances of the resonant capacitors. The realization of this patent only requires very simple and robust circuits making the cost low and the yield high.