Design of interleaved multilayer rosen type piezoelectric transformer for high voltage dc/dc applications

Research and development within piezoelectric transformer (PT) based converters are rapidly increasing as the technology is maturing and starts to prove its capabilities. Especially for high voltage and high step-up applications, PT based converters have demonstrated good performance and DC/AC converters are widely used commercially. The availability of PT based converters for DC/DC applications are very limited and are not that developed yet. I this paper an interleaved multi layer Rosen-type PT for high step-up and high output voltage is developed, for driving a 2.5kV dielectric electro active polymer actuator [17]. The targeted application utilises an inductor-less half-bridge driving topology, where the reward of eliminating the series inductor is a reduction in component count, size and price. The absence of a series inductance calls for other means to avoid large hard switching losses and obtain soft switching capabilities. This can be achieved by utilising an advantageous PT structure, which is the main advantage of the interleaved Rosen-type PT. Furthermore the design should be further optimised, in order to achieve soft switching capability. The goal of this paper is to develop a soft switching optimised PT, capable of generating output voltages higher than 2kV from a 24V supply voltage. Furthermore finite element method (FEM) has been the main tool through the PT development.