Critical design criterion for inductorless H-bridge driven piezoelectric-transformer-based power supplies

A methodology for predicting the ability of a piezoelectric transformer for achieving zero-voltage switching (ZVS) is presented. A describing function method is employed to obtain the PT equivalent circuit model operating under ZVS operation. This methodology is encapsulated within critical criterion which, if fulfilled, guarantees efficient ZVS operation over a wide load range. The model provides a quantitative measure of a PT’s ability to achieve ZVS using a H-bridge inductorless configuration. With the capacitance ratio profile provided by the analytical model, the limitations of the inductorless H-bridge driven PT-based inverters are indicated and guidelines for designing both PT and inverter control circuit are demonstrated.