Research Of Vibration Generating Device Based On Piezoelectric Material

With the increase of people's environment awareness and worry about the future energy crisis, mankind begin to search for new energy sources. Among many new energy sources, piezoelectric device has the advantages of simple structure, no heat, no pollution, no electromagnetism interference, and it is easy to machine, miniaturize and integrate. Therefore it has already became an new hot spot in the world.Utilizing the piezoelectric effect of piezoelectric material, we design a vibration generating device which can convert vibration energy from environment and magnetic field energy into electrical energy. Using piezoelectric materials combined with high-performance permanent magnetic materials, PZT cantilever which is the core device of the energy harvest is designed. When the natural frequency of the PZT cantilever is equivalent to the frequency of ambient vibration and alternating magnetic field, the resonance takes place, the system can absorb the maximum energy. The main work is summarized as follows:1. Basic theories of the piezoelectric effect for piezoelectric material, the characteristics of the piezoelectric power generator and the law that relevant parameters affecting piezoelectric power generator's performance are introduced. Systemically illustration the effect of the vibration mode, structure form, as well as the excitation way on the effect of the power generator. According to the vibration equation and the dynamic limit condition, the vibration theory for the piezoelectric cantilever was analyzed.2. Based on the theory of piezoelectricity and thermodynamic equilibrium, mathematic model was established. By using the finite element software of ANSYS, model and harmonic results of the structural size of bimorph cantilever are analyzed, and the influence of structural size and the exciting method of bimorph cantilever on static output voltage are analyzed also. All these results obtained from FEA are in good agreement with the result calculated by mathematic model.3. The unimorph and bimorph structure materials are produced. Harmonic vibration platform was built using magnetic field generated by the solenoid to simulate the magnetic field of high voltage. The unimorph and bimorph structure materials were studied, and the different dimensions of the piezoelectric cantilever output voltage results in different excitation conditions were analyzed. The bimorph structure material was studied on rotor vibration test bed.4. Using voltage doubler and super-capacitor design piezoelectric energy-harvesting circuit, which can achieve intermittently external energy supply.