Adjustable Nonlinear Springs to Improve Efficiency of Vibration Energy Harvesters

TL;DR

This paper proposes adjustable nonlinear springs to enhance the bandwidth and power output of vibration energy harvesters, addressing the limitations of resonance-based systems in shifting ambient vibration frequencies.

Contribution

It introduces a model of H-shaped nonlinear springs and demonstrates their benefits in increasing energy harvester output power through simulation.

Findings

Nonlinear springs can increase power output by up to 48%.

They enable harvesters to adapt to frequency shifts in ambient vibrations.

Simulation confirms improved performance over linear systems.

Abstract

Vibration Energy Harvesting is an emerging technology aimed at turning mechanical energy from vibrations into electricity to power microsystems of the future. Most of present vibration energy harvesters are based on a mass spring structure introducing a resonance phenomenon that allows to increase the output power compared to non-resonant systems, but limits the working frequency bandwidth. Therefore, they are not able to harvest energy when ambient vibrations' frequencies shift. To follow shifts of ambient vibration frequencies and to increase the frequency band where energy can be harvested, one solution consists in using nonlinear springs. We present in this paper a model of adjustable nonlinear springs (H-shaped springs) and their benefits to improve velocity-damped vibration energy harvesters' (VEH) output powers. A simulation on a real vibration source proves that the output power can be higher in nonlinear devices compared to linear systems (up to +48%).