Research On Piezoeleectric Energy Harvester

In recent years, with the advances in wireless technology, systems such as electronic equipment and sensors constantly expanding range of applications has been widely used in civilian, medical and military fields. Conventionally, the electronic devices are powered by chemical batteries with a short service life, requiring constant replacement, limited energy. Furthermore, in certain applications, battery replacement is very difficult, high cost or impossible. Therefore, it is very urgent on research of the alternative power supply.Vibration energy wide spreading in the natural environment, which can be extracted and converted to electrical energy by vibration generators. Vibration-based energy harvesting methods are generally three types:piezoelectric, electrostatic and electromagnetic. As opposed to electrostatic and electromagnetic, piezoelectric energy harvester has a simple structure, high energy density and long life and therefore more attention is acquired.Most of piezoelectric energy harvesters use the cantilever beam structures as inverting element. A piezoelectric energy harvester based on cantilever beam structure is researched in this thesis, whose principle is piezoelectric effect of PZT that transform mechanical energy to electricity. The main contents are listed below:1,The working principle of piezoelectric energy harvester is described. A piezoelectric cantilever/mass composite structure is proposed to harvest vibration energy in resonance mode. The mass is introduced to decrease natural frequency of the whole structure.2,Based on 3D finite element model of composite structure, the natural frequency, piezoelectric voltage are computed and their dependence on structure parameters such as length/width/height of the cantilever and mass are analyzed. Then Multisim equivalent circuit model is explored to resolve the voltage and power delivered to external resistance and release the output performance of the energy harvester.3,A testing system is used to measure the performance of a energy harvester. The system includes wave-form generator, power amplifier, vibrator, accelerator, oscillograph etc. The natural frequency, voltage output are measured or carried out. Testing results are compared with related simulation. Good agreement between them is obtained.