High-Efficiency Isolated Piezoelectric Transformers for Magnetic-less DC-DC Power Conversion

Piezoelectric components are promising alternative passive components for power conversion, offering high efficiency and high energy densities at small scales. In this paper, we model, design, and demonstrate isolated piezoelectric transformers (PTs) capable of high efficiencies and galvanic isolation as primary passive components in magnetic-less dc-dc converters. We present a design framework for radial mode PTs that enables them to simultaneously achieve peak efficiency and zero voltage switching in a power converter at a specified operating point. The proposed PT design strategy is validated in a dc-dc converter prototype that demonstrates efficiencies of >97% at multiple voltage levels. The converter achieves a peak efficiency of 97.6%, which represents a 17x reduction in loss ratio compared to previous isolated magnetic-less PT-based dc-dc converter designs.