Fundamental limits on energy transfer and circuit considerationsfor piezoelectric transformers

摘要

This work investigates fundamental limits on electromechanicalnenergy conversion capacity of piezoelectric transformers by consideringna work cycle analysis. Fundamental limitations in a losslessnpiezoelectric transformer are imposed by maximum electric fieldnstrength, maximum surface charge density, maximum stress and maximumnstrain. For the lossless case, the authors' analysis indicates that thenmechanical stress limit is the effective constraint in typical PZTnmaterials. For a specific PZT-5H sample considered, a mechanicalnstress-limited work cycle indicates that this material can handle 330nW/cm3 at 100 kHz. A second direction this work has taken hasnbeen an investigation into a soft-switching drive and control circuit,nthat does not require any magnetic components. The theory of operationnof soft-switching resonant drive circuitry is discussed, andnexperimental results on a soft-switching inverter incorporating nonmagnetic components are reported