Study On Radial Vibration Mode Of Piezoelectric Transformer

The Piezoelectric Transformer is a device that transforms voltage by Piezoelectric effect and converse Piezoelectric effect of ceramic material, relative to tradition electromagnetic transformer, it has the advantage of small, high set-up ratio, none-flammable, none-electromagnetic pollution etc. It has overcome the defect of electromagnetic transformer and it is the indispensable part in the electronic information system, and it could be used widely in source equipments substituting for the conventional electromagnetic transformer.First, the theory, application and general situation of the Piezoelectric Transformer were introduced briefly in this dissertation, then the choice of Piezoelectric ceramic, the design of driven circuit, the procedure of fabrication and testing were described. In the dissertation, the work has been done as follows:First, the influence of different Zr/Ti ratio and SiO2 dopant on the properties of PMS-PZT Piezoelectric ceramic has been investigated systematically, and developed the high electromechanical coupling factor(Kp=0.57), high mechanical quality factor (Qm=1553), high Piezoelectric constant (d33=325pC?N-1), high relative permittivity (εr=1642), and low loss factor (tanδ=4.30E-03) composition ceramics for Piezoelectric Transformer.Next, based on the effect of set-up ratio and frequency of the Piezoelectric Transformer, considerations and methods for designing driven circuit have been introduced. Then several designs of driven circuit and the working principle of these driven circuits have been discussed in detail. Finally, working results of the driven circuits have been verified by simulation and experiment.At last, a small scale radial mode Piezoelectric Transformer in wafer type has been manufactured, its maximum set-up radio is 4.06/mm, and its variational ratio of resonant frequency with temperature is less than 0.04 kHz/℃. The radial mode Piezoelectric Transformer is a new type Piezoelectric Transformer. It takes the advantage of the radial electromechanical coupling factor (Kp) which is larger than the transverse electromechanical coupling factor (K31) that Rosen type Piezoelectric Transformer takes. And then, low voltage, large current, high power can be easily gained with less bulk dimension. The radial mode Piezoelectric Transformer can be used in electronic ballast, adapter, DC/DC converter, etc.