驱动电压跟踪的超声波电机频率自适应技术

A Adaptive Frequency Tracking Control Strategy for Ultrasonic Motor Using the Driving Voltage

超声波电机在运行过程中由于温度的上升会引起谐振频率的漂移,谐振频率的漂移又会导致电机的转速、效率等性能发生改变,为此要求驱动电路有谐振频率的自动跟踪功能。该文从电机在谐振点附近的等效电路出发,分析了输入电压与谐振频率的对应关系并通过实验分别比较了温度和负载对电机动态电容电感乘积、谐振频率、驱动电压和转速的影响。利用一定负载下工作电压相对稳定以及温度对谐振频率影响是渐变的特点,提出了以电机驱动电压为控制对象、输入频率为控制量的超声波电机频率跟踪控制策略。结合直径60mm的行波型超声波电机实验验证了该控制策略的有效性,其中空载、轻载和重载时的速度波动分别控制在5.1%、6.3%、6.4%以内,而效率比不加控制策略时分别提高了0.88%、5.3%和3.1%。

The resonant frequency of the ultrasonic motor drifts during motor operating as the temperature rising.The frequency drifting has a great effect on the output performance of the motor,such as speed,efficiency.So the function of frequency tracking is needed in the driving circuit.The relation between input voltage and frequency was analyzed using the equivalent circuit,then the effect of the temperature and load on dynamic impedance,resonant frequency,driving voltage and the speed were analyzed by experiment respectively.A new frequency tracking control strategy with driving voltage was advanced based on the control of input voltage.At last,a 60mm diameter traveling-wave ultrasonic motor was tested in this research,The speed fluctuation was tested below 5.1%,6.3%,6.4%,the efficiency of the motor increases about 0.88%,5.3% and 3.1% under no-load,light-load and heavy-loads respectively.