| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 94 === Compared with wire-wound magnetic transformer, piezoelectric transformer ( PT ) has main advantages which include small and thin size, high efficiency power, no electromagnetic radiation, and so on. PT is gradually replacing magnetic transformer, especially in the application of the power supply of the liquid crystal displays ( LCDs ), because the tendency of electrical appliances is toward small and thin units.
Although piezoelectric transformer offers the advantages above, it is only used in high-price electronic appliances because of higher cost in PT than that in magnetic transformer. In addition, for higher thresholds of technologies needed, a few companies capably invest in PT fabrication in Taiwan. In this theme, the researches on the fabrication, design, and simulation are carried out. First, the electrical equivalent circuit of PT is derived based on mechanical and electrical theories to learn the PT voltage gain in terms of the ratio of poling lengths of output section to input section, and characteristic parameters of piezoelectric material. Then, with the ANSYS, the design and simulation of PT are done. The voltage gain versus frequency response and impedance versus frequency response can be obtained by finite element calculation. Third, the implementation of the PT with the dimension of 30.3 x 6.5 x 1.3 mm is completed by stages from mold patterning of piezoelectric ceramic dust, burning process to poling process. The performances of implemented PT are measured with instruments. The resonance and anti-resonance frequencies are 113.5 kHz and 111.3 kHz respectively.
Finally, the data comparisons of the parameters data from theory calculation, ANSYS simulation and instrument measurement are performaned. The difference of resonance and anti-resonance frequencies between simulation and measured data are 2.5kHz and 1.8kHz that difference rates are less than 1.6%. This demonstrates that the ANSYS simulation data are available to be used as pre-design references. It is greatly convenient for new PT designs and analyses in the future.
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