102 圧電コンポジットを利用した振動発電装置のエネルギー変換効率に関する考察(セッション1 モデル解析・設計)

Abstract

Authors have proposed a cantilever type of vibration energy harvester with piezocomposite for vibration condition monitoring applications of rotating machinery. Proposed energy harvester consisted of Macro-Fiber Composite (MFC) actuators in bimorph configuration. The dynamics of the vibration energy harvester can be modeled as a single degree-of-freedom, spring-mass-damper system with base excitation due to unbalance response of rotating machinery. Considering the electric circuit connected to the MFC, the equivalent two degree-of-freedom model is obtained. In this study, the energy balance equation is derived. The efficiency of vibration energy transfer to the electrical resistive load of the circuit is estimated by using the derived energy balance equation. The estimated generated maximum AC power is 105.3(μW) with the electrical resistive load 112.8(kΩ) at the resonant frequency of 26.25(Hz) under the excitation amplitude level 0.71(mm/s rms). It indicates that the impedance matching between MFC actuators and the electrical resistive load is effective for maximizing the AC power transfer of the vibration energy harvester. At this condition, input vibration power is calculated as 727(μW) from the energy balance equation, and then the efficiency of vibration energy transfer to the load is estimated as 17%.