超声波电机频率-温度特性研究

为了研究超声波电机运行过程中温升和频率漂移等关键技术问题,采用自然对流传热问题的牛顿冷却定律和热容理论,建立了超声波电机的温度特性与驱动频率之间的关系表达式,仿真分析了驱动频率对电机温升的影响;考虑电机压电定子的转动惯量和剪切变形等因素,利用能量等效原则和铁摩辛柯梁振动理论建立了超声波电机谐振频率与温度之间的关系表达式,通过仿真研究了温度对电机谐振频率漂移的影响,并通过实验验证了仿真结果的正确性。仿真及实验结果表明:电机的谐振频率随着温度的升高呈线性降低;驱动信号频率越接近电机谐振频率,电机表面温度就越高。最后,根据研究结果提出了减小电机温升和频率漂移的措施,并通过实验验证所提出措施的有效性。

Research on the frequency-temperature characteristics of the ultrasonic motor

In order to study the temperature rising and the frequency shifting problems during the operation of the ultrasonic motor(USM),the frequency-temperature characteristics of the USM were analyzed.The relation expression between the surface temperature and the exciting frequency of the USM was formulated by the Newton cooling law and the thermal capacity theory,some simulations were done to study the effects of the exciting frequency on the temperature performance of the USM.By considering the moment of inertia and the shearing deformation of the piezoelectric stator,the equation describing the resonant frequency and the temperature of the USM was established according to the equivalent principle and the Timoshinko beam theory,and the effects of the temperature on the resonant frequency of the USM were analyzed by simulations.Experiments testify the validity of the simulating results.The research results show that the resonant frequency of the USM is decreasing in linearity with the increment of the temperature,and the surface temperature of the USM is increasing with the reduction of the driving frequency when the driving frequency is above the resonant frequency.At last,an example proves the validity of the measures which can decrease the temperature rising and the frequency shifting of the USM.