Modeling and experimental analysis of rotating magnet receivers for electrodynamic wireless power transmission

An electrodynamic wireless power transmission (EWPT) approach that utilizes mechanically responsive receivers to safely deliver power in cluttered environments is presented. Mainstream WPT techniques are predominately based on near-field inductive coupling of two coils (MHz) or directed, far-field RF transmission (GHz) between a transmitter and a receiver. These approaches face significant technical hurdles (safety concerns, detuning, parasitic heating) in real-world scenarios where electrically conductive media exists in between the transmitter and receivers. The EWPT approach presented here relies on electrodynamic coupling between a magnetic near-field produced by a transmitter and a permanent magnet in the receiver. This approach enables wireless power delivery using low-frequency (<1 k Hz) fields, which facilitates transmission through and around common electrically conductive media such as metal objects, people, etc. Here, we present an electromechanical model of a rotating magnet receiver in order to analyze the transient and steady-state dynamics of the receiver magnet. We then experimentally demonstrate wireless power transmission with an efficiency of 7% to a 3 cm(3) receiver achieving 1.3 W (0.42 W cm(-3) power density) at 1 cm and 9 mW at 9 cm. These experimental results are well matched by simulations. Lastly, we demonstrate simultaneous charging of two wearable electronic devices in a cluttered environment.