Design of interleaved interdigitated electrode multilayer piezoelectric transformer utilizing longitudinal and thickness mode vibrations

In applications of high voltage and low power capacitor charging, conventional magnetic based power converters often suffer from bulky components and poor efficiency. Piezoelectric transformer (PT) based converters however, are compact and efficient, especially at high step-up applications. In this paper an interleaved interdigitated electrode (IDE) multilayer PT utilizing longitude and thickness mode vibration for high step-up and high output voltage is developed, for driving capacitive loads of up to 2.5kV. The PT possesses native soft switching capabilities, enabling the utilization of inductor-less topologies. One of the main advantages of the IDE´s is that it enables the PT to operate in longitudinal vibration and thickness mode through the electromechanical coupling coefficient k33. This also permits the realization of the PT through a low build-up height (below 2-4mm), making the manufacturing much easier and cheaper. As a result an interleaved IDE PT, with a soft switching factor of 1.00 and a gain of 38 has been developed.