Design and Performance of Miniaturized Piezoelectric Step-Down Transformer

Piezoceramics of the perovskite type PZT-PMN, of composition yPb(ZrxTi1-x)O3-(1-y)Pb(Mn0.3Nb0.3Sb0.3)O3 (0.45 < x < 0.52 and y = 0.90, 0.95), were prepared by mixed oxide processing. The materials were evaluated for the construction of a step-down transformer with a ratio of 10:1 and an output power of 10 W. An electromechanical coupling factor of 58%, a piezoelectric strain constant (d33) of 270 pC/N, a mechanical quality factor of 1520, a permittivity of 1500 and a Curie temperature of 350 C were achieved for y = 0.95 and x = 0.505. The corresponding values for y = 0.90 and x = 0.500 were 56%, 250 pC/N, 1820, 1120 and 290 C. The piezoelectric and dielectric properties decreased, whilst the mechanical quality factor increased, with increasing dopant concentration. Excellent properties were achieved at the morphotropic phase boundary regions. A multilayer structure is proposed for a transformer, to avoid the structural defects associated with conventional piezoelectric transformers. Finite element analysis and equivalent circuit analysis were used for the design and performance analysis. 9 refs.