Efficiency improvement of piezoelectric-transformer DC-DC converter

Abstract

Piezoelectric-transformers (PT) have a lot of merits in comparison with magnetic transformers. We have previously presented some types of piezoelectric-transformer DC-DC converters (PT-converters) for AC-adapters, but their efficiency was restricted. The maximum efficiency was less than 80%. Furthermore, the frequency characteristics of efficiency are not good due to the power loss generated in the input filter circuit of the PT. In this paper the improvement of the converter efficiency by using a different rectifier circuit topology and a synchronous-rectifier technique is described. Furthermore, the frequency characteristics of efficiency are improved by using a different topology of the input filter circuit and its optimum design. As a result, the converter efficiency has been increased up to 88% and the frequency characteristics of the efficiency is also improved.