Precise measurement of losses in piezoelectric transducer and its application to evaluation of piezoelectric transformer efficiency

Mechanical and dielectric losses were measured by the measurement method proposed in this paper in a piezoelectric transducer with input and output terminals. These losses must be considered in designing piezoelectric transformers used as power sources. In the method proposed here, the losses can be obtained using the experimental results of resonance angular frequency, quality factor and the resistive component of input impedance when the output terminals are short-circuited and opened, and using the measured phase angle difference between current and voltage when the output terminals are opened. In the method, a resonance frequency tracking circuit is utilized. Hence, there is an advantage that the measurement can be performed easily and in a short time. The results obtained by this method have also been used in the evaluation of the efficiency of piezoelectric transformers.