基于能量等效的行波型超声波电动机解析模型

提出一种基于能量等效的行波型超声波电动机稳态特性分析计算的解析模型.首先通过能量等效原则将压电复合定子环简化成复合等直梁模型,综合考虑压电复合定子的转动惯量和剪切变形的影响,利用铁木辛柯梁振动理论得到电动机定子振动的频率方程和强迫振动稳态解:其次,对电动机定、转子接触面的滑动状况进行分析,利用弹性接触理论确定了定、转子接触面的力传递模型和效率表达式,通过把定、转子接触面的摩擦损耗和转子的输出功率视为定子强迫振动的等效阻尼损失,由此建立电动机的机械特性和输出功率表达式;最后,仿真和试验分析了不同电动机结构和材料参数以及定子预压力、驱动频率和摩擦层厚度等对电动机振动特性和机械特性的影响,试验证明了该模型的有效性和适用范围.

Analytical Model of Traveling-wave Type Ultrasonic Motor Based on the Energy Equivalent Method

The analytical model was proposed to analyse the steady-state characteristics of the traveling-wave type ultrasonic motor (TWUSM) based on the energy equivalent method. Firstly, the simplified equivalent composite beam model of the piezoelectric stator was presented with the energy equivalent principle. By involving the rotary inertia and the shearing deformation of the piezoelectric stator, the equation describing the frequency and the amplitude of transverse vibration of the stator were obtained according to the Timoshinko beam theory. Then the force transfer model and the efficiency of the contact surface between the stator and the rotor were derived with the elastic contact theory. And the mechanical performance expression and the output power of the TWUSM were defined by regarding the friction loss of the contact surface and the output power of the rotor as one of parts of the equivalent damp loss of the stator vibration. Finally, all factors, such as the physical demension, the material parameters, the preload, the driving frequency and the friction layer characteristics, influence the vibration characteristics and the mechanical characteristics were analyzed, and the accuracy of the analytical model was verified by comparison with the experimental results.