A Coupling Factor Independent Wireless Power Transfer System Employing Two Nonlinear Circuits

Conventional linear resonant wireless power transfer (WPT) systems suffer from a significant performance degradation as the coupling factor between the transmit and receive coils varies. In this paper, based on the properties of a nonlinear resonant circuit, a WPT system that can maintain constant output power over a wide coil distance range is proposed. It employs passive nonlinear resonators in both the transmitter and receiver sides to regulate the output power without using active or control circuitry, frequency tuning or complicated coil configurations. A 60 W nonlinear WPT prototype circuit working at 1.5 MHz is designed and fabricated and compare with a similarly designed linear WPT circuit. The nonlinear WPT circuit is capable of maintaining almost a constant output power while the distance between the coils changes from 6 cm to 15 cm, a significant performance improvement as compared to the linear WPT circuit tested under the same conditions.