This study concerns a vibration energy harvester of resonance-type with a nonlinear oscillator which can convert the kinetic energy of the vibration source to electric energy effectively in a wide frequency range. The conventional linear harvesters are designed so as to generate larger power by matching the natural frequency of the oscillator to the frequency of the source vibration. The problem is, however, that if the input frequency changes even in a slight amount, the performance of the harvester can become extremely worse because the effective bandwidth of the resonance is quite narrow. In this study, the resonance frequency band of the oscillator is expanded by using a nonlinear oscillator with a nonlinear spring to allow the harvester to generate larger electric power in wider frequency range. However, the nonlinear oscillator can have multiple stable steady-state responses in the resonance band, and it depends on the initial conditions which solution emerges. In this paper, the mechanism of self-excitation is utilized to unstabilize the solutions except for the largest amplitude solution. A charging circuit with a variable resistance which is controlled from negative to positive as a function of the response amplitude is introduced in order to enable the oscillator entrained by the excitation only in the large amplitude solution. Theoretical and numerical analyses are conducted to show that the nonlinear energy harvester with resistance control can respond in large amplitude in wide frequency range, and a significant improvement is achieved in the regenerated power compared with the one without control.

Date Published: 27 April 2011
PDF: 9 pages
Proc. SPIE 7977, Active and Passive Smart Structures and Integrated Systems 2011, 79770V (27 April 2011); doi: 10.1117/12.880905

Published in SPIE Proceedings Vol. 7977:
Active and Passive Smart Structures and Integrated Systems 2011
Mehrdad N. Ghasemi-Nejhad, Editor(s)