Investigation on the Effect of Magnetic Coupling and Power Harvested in an Electromagnetic Vibration Energy Harvester.

An approach to ensure an increased power output on a resonant energy harvester through the magnetic flux/coupling between the magnets and transduction coil design was presented in this work. The power harvested on an electromagnetic energy harvester not only depends on the structural component but also relies on the electrical/coupling parameters. The flux/coupling variation reported in this work was achieved by using either air, steel, magnets, or a hybrid of air-iron-magnet design between the outer magnet space. The coupling/flux variation design was investigated using seven different models while the effective magnetic flux density on each different model was computed using the Finite Element Magnetic Methods (FEMM) software. The work reported here shows that using iron as the coupling material raised the flux density and power harvested by 8.37% and 1.76 % respectively compared to air. Also, using magnets as the coupling material increased the flux density and power harvested by 25.06 % and 3.99 %, respectively. In addition, the power per center magnet and iron volume was obtained at 1.21 $\mathrm{W}\mathrm{m}^{-3}$ and 1.18 $\mathrm{W}\mathrm{m}^{-3}$, respectively. It was concluded that using magnet as the center coupling material will result in a higher level of harvestable power for any electromagnetic harvester design geometry.