On the modeling and optimization of an electromagnetic energy harvester

The interest in modeling and prototyping the so-called Vibration Energy Harvesters (VEHs) has increased significantly in the last decades, given the growing demand for energy sources that can capture energy from the vibration of a machine, for example, to power small sensors and vibration monitoring devices. In this work, the design and optimization of a commercial Electromagnetic Vibration Energy Harvester (EMVEH) are presented. Such a device contains in its interior a resonant-type electromagnetic transducer, the latter composed basically by a seismic mass, a mechanical spring and a multi-turn coil. The complete set weighs about 90 g and occupies a total volume of approximately 50.97 cm3, being able to generate up 45mW at its resonance frequency of 60 Hz, with a bandwidth of 2.5 Hz. Furthermore, the linear generator presented in this paper reaches a maximum Normalized Power Density (NPD) of 1.8018mW/(cm3g2) at an acceleration amplitude of 0.7 g (∼ 6.67m/s2). To proceed with electromechanical modeling and further optimization, a numerical model was developed via commercial software COMSOL Multiphysics, from which it was possible to optimize its geometry in order to maximize its NPD and power output. A Surrogate optimization algorithm was then implemented in MATLAB, in which both volume and mechanical stress were considered as project constraints.