Resonant Frequency Control of the Ultrasonic Transducer Using Simulated Inductor

Dynamic resonant frequency control of the ultrasonic transducer during its operation is a promising technique for the various ultrasonic devices such as ultrasonic motors. In a previous study, we fabricated a transducer for this control using a passive piezoelectric parts additional to the conventional Langevin transducer. The principle of our previous method was based on the controllable piezoelectric material's stiffness between open and short electric boundary conditions. By switching between these conditions using field effect transistors, the resonant frequency was controlled continuously. In this study, to expand the resonant frequency control band, we introduced a simulated inductor composed of the resistors, capacitor and operational amplifier. Prepared simulated inductor showed good agreement with the equivalent circuit and by connecting it to the passive piezoelectric parts of the Langevin transducer, wider resonant frequency control was confirmed experimentally. Moreover, the control of the inductance of simulated inductor was composed.