High-power ceramic materials for piezoelectric transformers

Considering the characteristics of materials required for piezoelectric tra nsformers, and introducing the maximum vibration velocity v(max) that gener ates a fixed temperature rise, we can express the maximum output power of a piezoelectric transformer as the product of this v(max)(2), the square of the power coefficient on the output side A(2) and the load resistance R-L M oreover, the power coefficient on the output side A(2) is proportional to t he product of the square root of Young's modulus Y-E, the square root of th e electromechanical coupling coefficient k, and the permittivity epsilon(33 ) This is verified by using two types of piezoelectric transformers in an i nverter where the output section may be of the Rosen type or the transverse -effect type. It is shown that the contributions made by the structure of t he piezoelectric transformer and the load resistance differ in each case. T he Rosen structure is used in the piezoelectric transformer for the inverte r, and it is shown that a material with large maximum vibration velocity v( max) is useful in this case. (C) 1999 Scripta Technica, Electron Comm Jpn P t 3, 82(11): 86-92, 1999.