Effects of capacitive versus resistive loading on high transformation ratio piezoelectric transformers for modular design considerations

Piezoelectric transformers (PTs) can be useful as compact, high-voltage supplies. However, PTs cannot be fully utilized if the associated circuitry does not allow for the desired transformation ratio to be maintained. The effects of adding capacitive and/or resistive loads to a PT are being studied. Experiments and modeling suggest that the highest transformation ratios are achieved when both the resistive and reactive load elements are optimized, rather than only the magnitude of the impedance. Specifically, these effects are being studied to modularize the PT as a compact, high-voltage power supply for a variety of applications. This paper will analyze these loading effects and suggest a coupling method for maintaining high transformation ratios from Rosen-type PTs comprised of rotated y-cut lithium niobate.