Modeling and Simulation of Multiple Piezoelectric Transformer Converters

Piezoelectric transformers (PT) are an alternative to wire wound magnetic transformers because of numerous advantages i.e. being the electromechanical energy conversion, low EMI, a compact and low design, as well as a high potential of high efficiency and power density. The last two decades of research into piezoelectric transformer (PT) based power converters have led to some extensive improvements of the technology, but it still struggles to get its commercial success. This calls for further research in order to enable the utilization of the PT technology, its advantages, cost effectiveness and increase competitiveness. There are mainly two types of PT namely step-up PT using Rosen-type configuration and stepdown PT using radial-type PT. Rosen-type PT and many other non isolated conversion circuits have the inherit problem of the common neutral between the input and output that makes it difficult to connect the output in series like the magnetic transformer. Piezoelectric transformer model and its electrical circuit is been developed using bootstrap method, to overcome the problem of common neutral between input and the output. The output obtained is the summation of voltage level in the output side of each PT. The impact of load and output filter capacitor on the conversion ratio and resonant frequency is discussed. Simulation results of double-level PT and multi-level converter is been obtained. This paper proposes voltage summation of a multi-level concept for many PT connected together and can be used for high voltage application. Keywords— Piezoelectric transformer, bootstrap, Rosen