Study Of The Dynamic Analysis Of Ultrasonic Motor Based On Equivalent Circuit

An ultrasonic motor is a kind of motor with a completely new driving principle to obtain turning force. The motor converts a piezoelectrically excited resonant vibration of the stator into a rotational movement of the rotor by frictional forces. As compared with conventional electromagnetic motor, the ultrasonic motor possesses the following features: compactness in size, high-torque at a low-speed range, fast response, insensitive to magnetic fields, high holding torque when power if off and so on, the ultrasonic motor has the wide application foreground. But the following defaults affect the application of the USM, such as late development, high-nonlinear behaviors, difficult in control. The equivalent circuit model (ECM) can predigest the driving and controlling model of the USM. This paper carries on the research to the ECM on this foundation.This research mainly completed the following work:1. Systemically analysis is done on the history, development status, feature, application and so on. The research difficulty and development way is concluded. It is emphasized the urgency of this paper.2. The definition of the piezoelectricity and the characteristic of the piezoceramics arc introduced. The piezoelectricity equation is calculated from the basic relation of the piezoelectricity crystal. A few important parameters describing the physics characteristic of the piezoelectricity material is introduced.3. Modal assumption method is used to build the electro-mechanical dynamic model based on Lagrange Equation. It can calculate the modal mass, modal stiffness, natural frequency and the force factor.4. The electro-mechanical analogy principle is used to calculate the parameters of the ECM. The perfect ECM is educed considering the effect of the preload force, load and temperature. Thereafter, the derived model has been simulated in a Matlab-Simulink environment by suing the power-system toolbox and the results achieved have been compared to the real performance of the motor and thereby the validity of the model has been established.5. The experimental investigation of the performance characteristics of the motor is studied when operating under various working conditions. Based on the experimental data the invalidation reason of the USM is found and the perfect project is studied.