High power universal piezoelectric transformer

This study describes a multilayer piezoelectric voltage and power transformer that has one direction poling, operates in a wide-frequency range and delivers both step-up and step-down voltages by inverting the electrical connections. In this design, the input and output electrodes are on the same side of the disk and are isolated from each other by a fixed isolation gap. The electrode pattern is a ring/dot structure such that it uses radial mode for both input and output part that are built-in on the same ceramic disk. A prototype transformer was fabricated of size 15 /spl times/ 2.78 mm/sup 2/ having mass of 3.8 gm. In the step-down configuration at the constant output power of 6 W, the transformer characteristics across a 100 /spl Omega/ load were found to be efficiency = 92%, gain = 0.21 input voltage =110 V/sub rms/, and temperature rise = 20 /spl deg/C from the room temperature. In the step-up configuration at the constant output power of 5 W, the transformer characteristics across a 5 k/spl Omega/ load were found to be efficiency = 97%, gain = 9.5, input voltage = 16 V/sub rms/, and temperature rise = 8 /spl deg/C from the room temperature. A detailed equivalent circuit analysis of the transformer was done, and the results were found to be in excellent agreement with the experimental results.