Electrical Connection Modifications of Rosen-Type Piezoelectric Transformers for Enhanced High-Frequency Sensing

Piezoelectric transformers (PTs) are the essential components for compact, efficient, and high-voltage energy conversion in advanced electronic systems. Among these, the Rosen-type PT is widely utilized due to its structural simplicity and effective electromechanical energy transfer. However, its operational frequency is fundamentally limited by intrinsic material properties and geometric dimensions. This study presents an electrical connection modification that significantly increases the resonance frequency of a Rosen-type PT without altering its physical structure. Experimental validation was performed using a packaged single-layer lead zirconate titanate (PZT) transformer with the dimensions of $35.1\times 12\times 4.2$ mm and an initial resonance frequency of 67 kHz. Through the proposed modification, the resonance frequency was shifted up to 262 kHz, accompanied by an improvement in the voltage transfer ratio from 25 to 35. These enhancements are attributed to changes in impedance characteristics and mode coupling behavior induced by the reconfigured electrical excitation. Equivalent circuit models and impedance measurements confirm the underlying mechanism, introducing a dimensionless correction factor in the resonance formulation. The modified configuration also achieves a dramatic rise in power conversion efficiency—from 49% to 98%—highlighting its potential for high-frequency, miniaturized, and energy-efficient applications in power electronics, wireless power transfer, and energy harvesting systems. The results demonstrate that electrical connection reconfiguration is a practical and scalable strategy for extending the functional bandwidth and improving the performance of Rosen-type PTs, enabling their integration into high-frequency power electronics, wireless power transfer, and energy harvesting applications.