Modelling, simulation, and experimental verification of a pendulum-flywheel vibrational energy harvester

Abstract

Vibration energy harvesting has been a popular topic in recent years. This technology is promising in developing self-powered sensor nodes for health condition monitoring of machines or structures, especially in remote areas. This study proposes a pendulum-flywheel vibration energy harvester based on the electromagnetic energy conversion mechanism. The harvester has two motion modes, namely the pendulum mode and eccentric flywheel mode, and can switch between the two modes automatically in response to external excitations.We first establish a theoretical model and fabricate a prototype of the harvester for evaluating its performance. Then, experimental and theoretical methods are employed to estimate the parameters of the model, such as the dipole moment of magnets, the mechanical damping coefficients, and the optimal resistance of the external electrical load. The typical trajectories of different motion modes, the frequency response characteristics, and the influence factors on the basins of attraction of the harvester are studied with the theoretical model. It is found that the small magnet distance can broaden the frequency band and enlarge the amplitude of the dynamic responses of the system. This finding provides us with an approach to control the performance of harvester and enables it to have stronger adaptability to variant ambient vibration in nature. Finally, laboratory tests are performed to validate the theoretical model. The experimental data verified the assumption that the rotation speed of the pendulum and the induced electromotive voltage have a linear relationship. Experimental and numerical simulation results show that the errors between them in most cases are less than 10% when the excitation displacement is small and have a slight increase with the excitation displacement. In the experiments, this harvester achieves a maximum power of 16.3 mW, exhibiting good performance in comparison with the-state-of-the-art pendulum-based harvesters.