Abstract: The present invention relates to a bi-directional piezoelectric power converter comprising a piezoelectric transformer. The piezoelectric transformer comprises an input electrode electrically coupled to a primary section of the piezoelectric transformer and an output electrode electrically coupled to an output section of the piezoelectric transformer to provide a transformer output signal. A bi-directional switching circuit is coupled between the output electrode and a DC or AC output voltage of the power converter. Forward and reverse current conducting periods of the bi-directional switching circuit is based on the input drive signal or the transformer output signal such that a forward current is conducted from the output electrode through the bi-directional switching circuit to the DC or AC output voltage in a first state to charge the DC or AC output voltage.

Abstract: The present invention relates to a piezoelectric power converter comprising an input driver electrically coupled directly to an input or primary electrode of the piezoelectric transformer without any intervening series or parallel inductor. A feedback loop is operatively coupled between an output voltage of the piezoelectric transformer and the input driver to provide a self-oscillation loop around a primary section of the piezoelectric transformer oscillating at an excitation frequency. Electrical characteristics of the feedback loop are configured to set the excitation frequency of the self-oscillation loop within a zero-voltage-switching (ZVS) operation range of the piezoelectric transformer.

Abstract: The present invention relates to a piezoelectric transformer comprising an elongate piezoelectric ceramic body adapted to operate in fundamental thickness mode. The elongate piezoelectric ceramic body comprises a central input or primary section coupled to adjacently arranged first and second output sections. High power conversion efficiency and zero-voltage switching capability is achieved by providing a primary side effective electromechanical coupling factor keff—P, which is larger than a secondary side electromechanical coupling factor, keff—S.