A Position-Insensitive Wireless Power Transfer System Employing Coupled Nonlinear Resonators

Conventional magnetically coupled resonant wireless power transfer (WPT) systems suffer from a significant performance degradation as the coupling factor between transmit and receive coils changes from its optimum value. In this article, a new WPT circuit that consists of two passive nonlinear resonators in both the transmitter and receiver is proposed. The circuit can adapt well to a wide range of coupling factor variations to provide constant output power without using any active control circuitry, frequency tuning, or complicated coil configurations. Both analytical and numerical simulations for the WPT circuit are provided. A 60-W nonlinear WPT prototype circuit operating at 1.5 MHz is designed, fabricated, and measured. The results show that the WPT system based on the proposed circuit is capable of maintaining almost a constant output power, while the distance between the coils varies up to 15 cm, a significant performance improvement compared to the linear WPT circuit tested under the same conditions.