Study of a 2DOF bistable energy harvester with variable potential well for ultra-low frequency vibration energy harvesting

A two-degree-of-freedom bistable energy harvester with a spring–magnet oscillator designed for ultra-low frequency vibration energy harvesting is presented in this paper. It combines magnetic plucking frequency upconversion and a variable potential function to achieve a high-efficiency response while also being suitably installed for applications with spatial limitations. A lumped parameter model of the piezoelectric energy harvester and the magnetic dipoles is applied to develop the theoretical model for the system. The prototype is fabricated, and experimental parameter investigations are undertaken to examine the effects of various factors, including magnetic distance, stiffness, and tip mass. The results indicate that at a frequency of 1.2 Hz and an acceleration of 0.23 g, the maximum output power reaches 264.6 µW at an optimal resistance of 250 kΩ.