A Comparison of Current-Carrying Coil Versus Rotating Magnet Transmitter For Electrodynamic Wireless Power Transmission

This paper experimentally investigates electrodynamic wireless power transmission (EWPT) using two types of transmitters: a current carrying pancake coil transmitter and a rotating magnet transmitter. Each transmitter is used to drive a receiver, but for the same magnetic field amplitude $(0.5 \text{mT})$ at the same distance $(\sim 12 \text{cm})$, the rotating magnet transmitter produces a more complex, rotating biaxial magnetic field in comparison to the uniaxial field produced by a traditional coil transmitter. At a field strength of $501 \mu \text{T}$, the receiver, connected across a $5 \Omega$ resistive load generated 149 mW at 356 Hz when driven by a rotating magnet transmitter compared to 38 mW at 241 Hz, resulting in 3.9 times more power output with the rotating magnet transmitter. The receiver driven by the rotating magnet transmitter corresponds to a normalized power density of $543 \text{mW} / \text{cm}^{3} \cdot \text{mT}^{2}$.