Abstract
Vibration energy harvester is a technology of converting vibration energy into electric power. The final purpose of this research is to develop a vibration generator that keeps the maximum power generation efficiency by adaptively changing the natural frequency of the vibrator to track the unknown frequency of vibration source. In this paper we consider a simple case where the frequency of the vibration source is constant being equal to the natural frequency of the generator, and the vibrator’s amplitude is to be controlled to meet a target value. In the previous studies, the steady-state oscillation control was proposed to solve the problem by which the charging current of capacitors was dynamically varied by a resistor, allowing a energy dissipation of the resistor. In this study, we propose a similar oscillation control system but without resistor for current control, by utilizing the charge/discharge cycle of capacitors as the control input. Experimental results show that the vibrator’s amplitude can be maintained at a target value by setting PI gains appropriately in the proposed system.
