Non-Isolated DC-DC Converter Implementations Based on Piezoelectric Transformers

Piezoelectric transformers (PTs) offer several potential advantages for converter miniaturization, but most attempts to use them in dc-dc converters have included magnetic components or have demonstrated poor efficiencies. For converters relying only on a PT for energy storage, we demonstrate that specific topologies and switching sequences that effectively utilize the PT for energy storage can improve performance compared to standard resonant converter topologies. In this work, we systematically enumerate non-isolated dc-dc converter topologies and switching sequences that most efficiently utilize PTs as their only energy storage components. These proposed switching sequences are selected for high-efficiency behaviors (e.g. zero voltage switching (ZVS) and maximum PT cycle utilization), and we provide a model for estimating the PT's efficiency to aid evaluation of these implementations. We then validate these analyses with experimental data from an example prototype for one proposed switching sequence.