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AC–DC Converter Based on Parallel Drive of Two Piezoelectric Transformers

An AC–DC converter based on a parallel drive of two piezoelectric ceramic transformers was investigated. The transformers operate in a fundamental contour extensional vibration mode which has a large electromechanical coupling factor notwithstanding the use of a piezoelectric transversal effect. The converter includes Al electrolytic capacitors for smoothing circuits and metal oxide semiconductor field effect transistors (MOSFETs) for the switching and rectifying circuits. Maximum converter efficiency of 90% was obtained. The prospect of a low profile, highly efficient and high power (more than 50 W) AC–DC converter with piezoelectric transformers has been obtained through these experimental results.