Abstract
This study is to develop the mechanism for the improvement of efficiency of a vibration energy harvester. Vibration energy harvesters are required to resonate with vibration of the structure as vibratory source for high efficiency, even when the frequency of vibratory source is not constant. In our laboratory, we devised a test equipment of the vibration system in which resonance automatically follows the fluctuated excitation frequency. The transverse motion of the plate spring enables the equipment to change its own natural frequency. Under the excitation, the test equipment automatically tunes its natural frequency in such a way as to match the excitation frequency without any controllers. Applied to a vibration energy harvester, the test equipment we devised improves generating efficiency under the situation that the excitation frequency of the mechanical vibration changes. However, the detailed mechanism that the test equipment automatically tunes its natural frequency into excitation frequency has not been explained. In this paper, we consider the factor of the transverse motion of the plate spring through excitation experiments and detailed observation.
