DC-DC Converter Implementations Based on Piezoelectric Transformers

The drive to miniaturize power electronics motivates investigation into alternative passive component technologies such as piezoelectrics, which offer fundamentally higher power density and efficiency capabilities at small scales compared to magnetics. Piezoelectric transformers (PTs) have seen application in dc-dc converters, but these designs typically require additional magnetics for competitive efficiency. In this work, we systematically enumerate isolated and nonisolated dc-dc converter topologies and switching sequences capable of efficiently utilizing PTs as their only energy storage components. The proposed switching sequences maintain high-efficiency behaviors (e.g., zero voltage switching (ZVS), all-positive instantaneous power transfer, and minimal charge circulation) across wide voltage gain and load ranges. We present techniques for deriving these switching sequences' ZVS regions, estimating PT efficiency, and solving for periodic steady state switching times; these offer insights for comparing and implementing design options. We then verify our analyses in a 180-500 V experimental prototype based on a commercially-available PT, which demonstrates significant efficiency gain through a proposed implementation.