Analysis of ultrasonic linear motor by using finite element method and equivalent circuit

In this paper, the three-dimensional finite element method and construction of an equivalent-circuit for the linear ultrasonic motor, is presented. The validity of the three-dimensional finite element routine in this paper is experimentally confirmed by analyzing the impedance of a piezoelectric transducer. Using this confirmed finite element routine, the impedance and vibration mode of a linear ultrasonic motor are calculated. Elliptical motion of the contact point between vibrator and rail of a linear ultrasonic motor is shown for determination of the contact point. Using the finite element method and analytic equations, characteristics of linear ultrasonic motor, such as thrust force, speed, losses, power and efficiency, are calculated. And the results are confirmed by experiment. Finally, equivalent circuit parameters of the linear ultrasonic motor are obtained by three-dimensional finite element method and analytic equations.