Piezoelectric transformers (PTs) are solid-state devices that transform electrical energy
into electrical energy using mechanical vibration. These devices are manufactured using
piezoelectric materials that are driven at the resonance. The initial concept of a piezoelectric ceramic transformer was proposed by Charles Abraham Rosen in 1954.[reference]
A simple DC-DC converter based on piezoelectric transformer was built. A programmable waveform genereator (AD9833) produces a square wave at a frequency close to the resonance of the piezoelectric transformer (around 70kHz). This square wave controls a HEXFET half bridge (IRF840 and IRF9540) through a SN754410 driver. The piezoelectric transformer is connected to the output of HEXFET half bridge in series with a small inductance (L1). The high voltage is rectified using fast recovery diodes 2CL75 (15kV/5mA). The control interface consists of an Arduino, OLED display, and rotary encoder. The OLED display provides information about the current frequency and voltage. By tuning the piezoelectric transformer to the resonance, a voltage in excess of 30kV was achieved.