A Frequency Automatic Tracking Function Of The Ultrasonic Motor Drive Power Supply Design

Ultrasonic motor (USM) is a new principle micro-motor that has been developed in recent twenty years. It is different from traditional electromagnetic motors. Ultrasonic vibration is excited by the converse piezoelectric effect of piezoelectric materials and magnified by the elastic body. With the friction coupling, the rotation or linear motion of the rotor is generated. Simple structure, low speed and high torque, no electromagnetic interference, and high holding torque when power is off, characterize USM. USM is widely applied in micro-mechanism, robots, precise instruments, automobile, spacecraft and other fields.Since more than twenty years, USM research has made great progress and certain types of motor have been industrialized. In order to adapt to the industrial development of USM, the research on driving and controlling technology must be strengthened. At present, high-performance driving power supply has become a research hotspot in home and abroad. On the basis of theoretical study, a frequency-tracking power supply of USM is designed in this thesis.The main work accomplished in this thesis is summarized as follows:(1) Introducing the basic principle, unique advantages, the development history of USM and the meaning and main contents of this thesis.(2)Analyzing the impedance characteristics of USM, studying the reasons of resonant frequency drifting, and then summarizing the methods of frequency tracking.(3)Designing a frequency-tracking driving power supply of USM. The fundamental of frequency tracking is keeping voltage-current phase difference unchanged and this method is realized with phase-locked loop CD4046.(4)Testing the power supply designed. Experimental results prove this power supply effective and the frequency-tracking method used feasible.