Modeling of a disk-type piezoelectric transformer.

In this paper, an electromechanical model for a disk-type piezoelectric transformer (PT) is proposed. To establish this model, vibration characteristics of the piezoelectric disk with free boundary conditions are analyzed in advance. Based on the vibration analysis results of the piezoelectric disk, the operating frequency and vibration mode of the PT are chosen. Then, electromechanical equations of motion for the PT can be derived based on Hamilton's principle, which can be used to simulate the coupled electromechanical system for the transformer. Voltage step-up ratio, input impedance, output impedance, input power, output power, and efficiency can be calculated by the equations. Thus, the optimal load resistance and the maximum efficiency for the PT are also calculated in this paper. Finally, experiments were conducted to verify the theoretical analysis, and good agreement was obtained.