Free Stator Modeling of a Traveling Wave Ultrasonic Motor

An equivalent circuit method describing the free stator of piezoelectric motor is presented in this paper, while the circuit elements have complex values. The mechanical, dielectric and piezoelectric losses associated with the vibrator are accounted for by the imaginary components of the circuit elements. It is shown that the calculation of the circuit parameters from the complex elastic, dielectric and piezoelectric material constants is straightforward and the model accuracy is verified with simulation around the important frequencies suitable for motor controller design purposes