Speed and Torque Characteristics of Three-Phase Ultrasonic Motor

A three-phase ultrasonic motor was proposed as an actuator for small precision machinery. Twelve ceramic plates were attached on upper and bottom sides of the metal plate. When three-phase alternating voltage was applied to the stator, elliptical displacements were generated at the three inner edges of the stator. The displacement characteristics and resonance frequency were obtained by using a finite element analysis program. The maximum displacement was occurred at frequency of minimum impedance. The effectiveness of the proposed design was verified experimentally. By measuring characteristics of the motor such as speed and torque. When pre-load to rotor was increased, motor speed was decreased and torque of the motor was increased. Three contact points between the rotor and stator made stable driving of the motor.