Modeling and design of piezoelectric transformers for low power applications

Piezoelectric transformer (PTs) advantages compared to magnetic components for power supplies are high power density, high voltage conversion ratio, high isolation voltage and low radiated EMI. PT design is not an easy task because it presents many variables (material, shape, number and thickness of primary and secondary layers, electrode distribution...) which can be selected in very different ways. Analytical 1 dimension (1D) models are widely used for PTs design in order to validate it before constructing the prototype. With finite element analysis (FEA) tools it is possible to optimize the design taking also into account the geometric effects, the manufacturing tolerances and the influence of the fixing on the PT performance. Fixing the PT is a critical design point, because the vibration of the PT can be perturbed, modifying its electrical performance. In this paper, a method for modeling and design PTs is proposed, combining analytical 1D models and FEA results. Experimental results with a PT sample will be presented too.