Normally, the way to transform a voltage of a power supply is to use the electromagnetic effect. In applications, however, in which magnetic fields may not occur, this can also be done mechanically by a piezoelectric transformer. The piezoelectric transformer considered here consists of several parts. Three brass and two piezoceramic rods, that are glued together. The purpose of the system is to transform a determined input voltage to a determined ouput voltage with a high efficiency. Therefore, one of the piezoceramics is excited harmonically with a frequency close to a resonance frequency of the system. According to the electromechanical coupling in piezoceramics, the transformer oscillates with the excitation frequency. Due to the piezoelectric effect an electric displacement or an electric voltage is generated between the electrodes of the second piezoceramic. The amplitude of this output voltage depends on the geometries of the five sections and on the electric impedance Z which is connected to the electrodes of the second ceramic. A model for such a piezoelectric transformer is derived and the results of the theoretical model are compared with experiments. [References: 1]
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