Principle Design and Characteristic Analysis of Ultrasonic Motor for Direct Drive Servo Valve

Abstract:

To meet the design requirements of a rotary direct-drive servo valve for a small length-to-diameter ratio compact structure of the drive motor， an annular traveling wave type ultrasonic motor was designed starting from the demand of 200 Hz dynamic response of the servo valve power level. The basic working principle of the ultrasonic motor is analyzed and the stator-rotor friction transmission model of the ultrasonic motor is established. An ultrasonic motor characteristic test bench was built and the torque-speed test was conducted， based on which， the analysis of the influence characteristics of ultrasonic motor drive frequency and drive voltage was performed. The results show that the ultrasonic motor has the maximum working efficiency at a drive frequency of 49.8 kHz， the servo valve speed and torque working demand can be satisfied when the drive voltage is greater than 110 V， and the maximum working efficiency can be approached under a drive frequency of 49.8 Hz and 110 V drive voltage condition.

Key words:direct-drive servo valve;dynamic response;ultrasonic motor;modeling design;experimental test