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当前航空航天领域内对超声电机,特别是行波型超声电机(下文简称超声电机)的需求越来越大.而超声电机在使用过程中的非线性现象导致的问题越来越突出.目前亟待解决的超声电机非线性问题是超声电机工作在一定的扭矩负载(小于堵转扭矩)状况下会出现突然停机的现象.该文分别从振动特性和电学特性分析了电机的骤停现象,提出行波型超声电机负载扭矩增加会导致电机定子阻尼和刚度同时增加,从而导致振动阻尼比减小.电机定子振动阻尼比减小会导致电机实际的共振频率升高.同时,负载增大会导致电机系统在同一频率下的阻抗模减小,使得电机实际的共振频率进一步升高.电机驱动频率不变,当电机实际的共振频率升高并从低到高穿越电机驱动频率时,超声电机会出现骤停现象.实验证明,负载扭矩增加导致电机系统阻尼比减小和电机系统阻抗模减小是影响到电机带载骤停的根本原因.“,”Greater growing demand for ultrasonic motor in aeronautics and astronautics engineering,especially the traveling wave type ultrasonic motor (ultrasonic motor),highlights its nonlinear problems.It is time to provide an appropriate explanation for the ultrasonic motor's sudden stoppage while working with load torque less than the locked torque.This paper analyzed this sudden stoppage phenomenon from vibration characteristics view and electrical properties view respectively,and found that the load torque change would increase or decrease the stator damping and stiffness simultaneously.These two important influences boost or diminish the ultrasonic motor stator's current vibration damping ratio.At the same time,bigger load distinctly decrease the impedance of the ultrasonic motor system,and further amplifying the actual resonance frequency.According to the unchanged driving frequency,sudden stoppage phenomena occurred when the practical motor resonance frequency became from low to high,until it equaled to the driving frequency.All experimental results clearly verify that the real influence factors for ultrasonic motor sudden stoppage are the increasing or decreasing of damping ratio and motor system impedance,led by the load torque changes.