Levitation-induced vibration energy harvesters

We report the scaling analysis of levitation-induced vibration energy (LIVE) harvesters. The analysis was conducted on the double-repulsion configuration in the moving magnet composite. This configuration has been shown to reduce the electrical damping from the coils, improve the dynamics, and increase the power output response of the harvester. The scaling analysis covered a broad length scale from micro to macro scale based on the distance between the stationary magnets (d = 0.36mm to 360mm) and a wide range of applied base accelerations from 0.01g to 10g. The magnetic flux calculations showed similar flux densities across all the length scales. However, the magnetic force field exhibited a linear response to scaling. The linear stiffness increased with increasing size while the nonlinear stiffness decreased with increasing size. The resonance frequency decreased with increasing scale regardless of the applied base acceleration while the peak velocity also decreased with increasing scale due to the decreased spacing. The resonance frequencies and bandwidth however increased as the applied acceleration increased. Also, the voltage and power response of the harvesters for any given acceleration scaled by 2-4 orders of magnitude as the distance between the stationary magnets was scaled by one order of magnitude. The model was compared with the experimental harvester and the results were in close agreement.