Analysis on the Ring-Type Piezoelectric Ceramic Transformer in Radial Vibration

A new type of ring-type piezoelectric ceramic transformer in radial vibration is studied. It is composed of two concentric piezoelectric ceramic thin rings polarized axially and radially. Based on the electromechanical equivalent circuit, when the dielectric loss of the piezoelectric ceramic materials and the mechanical contacting loss between the input and the output piezoelectric rings are taken into account, the electromechanical characteristics of the piezoelectric transformer are studied. The dependence of the voltage gain, the power gain, or the efficiency (the ratio of the output power over the input power) and the effective electromechanical coupling coefficient on the geometrical dimensions are analyzed. Meanwhile, the load dependence of the electromechanical parameters of the transformer is also investigated. Some prototypes of the piezoelectric transformers are designed and made. The resonance/antiresonance frequency and the voltage gain are measured. It is shown that the measured electromechanical parameters are in good agreement with the theoretical results. The conclusions can be used for the optimization design of the ring-type piezoelectric ceramic transformers in the engineering applications.