Resonant driving control for low power supplies with piezoelectric transformer

A resonant driving scheme for low power supplies using a piezoelectric transformer is presented. The proposed method, by exploiting the resonance of an additional inductor with the piezoelectric device input capacitance, allows the piezoelectric transformer to be driven at high efficiency independently of the matching between the inductor value and transformer characteristics. At the same time, the solution also allows the output voltage to be regulated by means of a feedback which controls the input voltage frequency by varying the inductor charge time interval. To verify the proposed scheme experimental results are given.