Dynamics of a three-parameter electromagnetic vibration energy harvester considering electromechanical coupling

Abstract

The paper concerns the dynamic responses and vibration energy harvesting characteristics in an electromagnetic vibration energy harvester comprising three-parameter mechanical vibration subsystem. For completeness and comparison, a two-parameter vibration energy harvester is also presented. The analytical expressions of the amplitude-frequency and phase-frequency responses of the inertial mass and the current in the electrical circuit are respectively derived by applying dimensionless method to the studied two- and three-parameter dynamic systems. Considering the effects of different types of ambient excitation, a single-frequency harmonic load and a periodic load are introduced into the analytical expressions on the dynamic performance of the vibration energy harvester. First of all, the influences of the designing parameters from the mechanical vibration subsystem and the electrical circuit subsystem on the vibration energy harvester are investigated. For evaluating the effects due to introducing the three-parameter mechanical vibration component, comparisons are made between two- and three-parameter vibration energy harvesters to convert the ambient excitations into electrical energy. And then, the expressions of the dimensionless average power which delivered into an electrical load under a single-frequency harmonic excitation or a periodic excitation are derived. The calculating results show that the energy conversion efficiency is enhanced significantly by changing the mechanical damping efficiency and the stiffness ratio for the three-parameter mechanical component of the energy harvester. At the same time, the average power of the three-parameter vibration energy harvester, which delivered into the electrical load, is also improved. However, the influences of the electrical circuit component on the ambient energy harvesting can be omitted when keeping the designing parameters of the mechanical part constant.