Design And Research On The Multipurpose Piezoelectric Energy Harvester Scavenging Energy From The Low-Frequency Mechanical Motions

In recent years, the research on piezoelectric energy harvesting technology has made rapid progress and become a frontier hotspot in the field of micro energy, and it can provide a feasible idea to solve problems of power supply for low-power electronic devices. However, some existing conventional piezoelectric energy harvesters(PEHs) still suffer from uni-directional sensitivity, which can not realize energy scavenging from multi-directional and diverse mechanical motions.In order to overcome this deficiency of conventional PEHs, a multipurpose beam-roller PEH is designed, which can scavenge both vibration energy in the horizontal and vertical direction and sway energy along the guide rail rolling direction. In this paper, the harvesting characteristics of vibration energy and sway energy are mainly studied, and the relative research work is presented.For vibration energy harvesting, the multipurpose beam-roller PEH scavenging energy from vertically directional vibration is mainly studied. However, scavenging energy from horizontally directional vibration is not described in detail, because the horizontally directional vibration and sway result in the same movement for the beam-roller PEH. Firstly, the PEH is modeled, and then the open-circuit charging characteristic of the PEH in its resonance state is simulated on the basis of the model. Secondly, the analytical study and numerical simulation of both transient and steady-state charging processes of an energy harvesting system have been made. Finally, both open-circuit and system charging characteristics of the PEH are verified experimentally. The comparative results indicate that theoretical modeling and simulation analysis of the PEH are scientific.For sway energy harvesting, the multipurpose beam-roller PEH scavenging energy from sway along the guide rail rolling direction is mainly studied. Firstly, based on the assumption of the lumped parameter,a theoretical model of the PEH is established, and then the form of open-circuit output voltage and transient charging process of the charging system capacitor are simulated. Furthermore, based on the experimental platform, both open-circuit voltage of the PEH and charging voltage of the system capacitor are obtained. The results indicate that the experimental results are basically consistent with the simulation. Finally, the effects of the initial displacement, sway angle and sway frequency on the open-circuit voltage of the PEH are systematically discussed by analysing several groups of experimental data.