High Efficiency Vibration Energy Harvesting Through Combined Isolator and Absorber Approach

Abstract

Abstract Relative motion is required for vibration energy harvesting, such as magnet moving past the coil in inductive approach and tip-mass motion in piezoelectric approach. Typically, relative motion is created by amplifying the source displacement and storage of mechanical energy in an auxiliary vibrating mass. In this study, we propose a novel technique to create the relative motion without amplification of the original source displacement. The technique relies on cancelling the vibration at one location and transferring the source vibration directly to another location through combination of a vibration isolator with a vibration absorber. In this multi-degree of freedom configuration, the power is harvested from the displacement of the vibrating source rather than the displacement of an auxiliary mass. This configuration eliminates the need to capture relative motion with respect to an externally fixed component. A prototype was designed and fabricated based on this concept which was found to harvest 45 mW at 0.9 G base acceleration and weighed 462 g. Through analytical modeling it was determined that the prototype could generate 87 mW @ 1 G base acceleration, while weighing only 243 g. Also, an optimal balance between the bandwidth and the maximum power harvested was identified through parametric analysis.