Critical design criterion for achieving zero voltage switching in inductor-less half-bridge driven piezoelectric transformer based power supplies

A methodology for predicting the ability of inductorless-driven piezoelectric transformer (PT)-based power supplies to achieve zero voltage switching (ZVS) is presented. A describing function approach is used to derive an equivalent circuit model of the PT operating in the vicinity of ZVS and the subsequent application of the model provides a quantitative measure of a PT's ability to achieve ZVS when driven by an inductorless half-bridge inverter. Through detailed analysis of the analytical model, the limitations of the inductorless half-bridge-driven PT are exposed from which guidelines for designing both the PT and inverter are derived.