Multilayered Unipoled Piezoelectric Transformers

This study describes a multi-layer piezoelectric voltage and power transformer which 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 gap. Investigations were performed on a disk of diameter 29.1 mm. The electrode pattern is a ring/dot structure, where a strip connects the dots. Various ratios of input to output area were studied and it was found that area ratio in the range of 2.8–3.3 or the output diameter in range of 13–15 mm yields high power and efficiency. The power density for the optimized single layer transformer was 40 W/cm3 while that for the 3-layer structure was 25 W/cm3. Though the power increased with multilayer structure, the effective power density decreased because of the interlayer constraints.