Equivalent Circuit Modeling of an Asymmetric Disc-Type Ultrasonic Motor

This paper presents an equivalent circuit model of an asymmetric disc-type ultrasonic motor and discusses its applications in the evaluation of the motor´s characteristics. The modeling process is based on the mechanical vibrations of the piezoelectric ceramic disk in both the radial (tangential) and coupling directions, the rigid body assumption of the rotor, and the assumption of a single contact point between the stator and the rotor with the most significant lateral elliptic motion effect. The overall model is composed of three admittance-type equivalent circuit models of the metal back plate, the stator, and the rotor. The advantages of the model are exemplified by comparing the numerical and experimental results, thereby showing that the model may be useful and pragmatic for electrical engineers in designing, simulating, and characterizing such motors.