An Eccentric Pendulum Energy Harvester for High-Speed Rotational Applications

A compact eccentric pendulum energy harvester for harnessing energy from high-speed rotational motion is presented in this paper. Electromagnetic transduction is developed inspired by the slotless brushless motor topology to convert mechanical energy to electrical energy. Relative motion between a coil-array mounted on a host rotational shaft and a suspended sleeve containing an alternating array of magnets enables this energy conversion. This is achieved by taking advantage of gravitational torque from the eccentric mass on the magnetic sleeve, which counteracts the electromagnetic torque applied on the sleeve due to electromagnetic coupling between the magnets and the coils. An experimental prototype was developed that was tested at speeds up to $250rad/s$ to study the electromechanical properties and critical operating speed of this energy harvester. The novel device could stably operate with $45\ g$ eccentric mass at speeds up to $235rad/s$ and extract maximum peak power of $23.4\ mW$ with $100\Omega$ external load at $210rad/s$ .