Abstract
This study describes an electromagnetic vibration energy harvester with a nonlinear oscillator. The oscillator with a nonlinear spring can have a bended resonance peak with multiple stable steady-state responses in the resonance band typically the large and small amplitude solutions depending on the initial conditions. We introduce a self-excitation circuit with a variable resistance which can take two values with negative and positive switched according to the level of the response so as to enable the oscillator entrained by the excitation only in the large amplitude solution. In this paper, possible improvement of the resistance switching to realize more rapid entrainment is mainly discussed. A switching control law according to the instantaneous state variables, i.e., the displacement and the velocity, is newly proposed, and the effect of the selection of the threshold values for the switching is examined. The results suggests the possibility of rapid entrainment by tailoring the threshold values according to the characteristics of the excitation.
