Effects of electrode layouts on voltage gain characteristics for ring-shaped piezoelectric transformers

This paper investigates voltage gain characteristics of ring-shaped piezoelectric transformers (PTs) based on piezoelectric rings with gap circles. The characteristics include relationships between voltage gains and driving frequencies, maximum voltage gains and maximum gain frequencies. Each ring contains a piezoceramic ring and two silver electrodes, where one of the electrodes is divided into two sub-electrodes as input and output electrodes of a PT using a gap circle, and the other electrode is used as a common electrode of a PT. The structure and principle of a PT based on a piezoelectric ring are first stated. Then, an electrical analysis of a ring-shaped PT is analyzed by an equivalent circuit model. Moreover, an ac power supply, including a dc/ac resonant inverter and its related facilities, is constructed to generate a sinewave voltage at input terminals of a PT. Furthermore, effects of geometrical and electrical conditions such as gap circles, load resistances and operation frequencies on voltage gain characteristics of ring-shaped PTs are measured and discussed.