多峰超声振动系统频率自动搜索和跟踪

在大功率超声应用中，由于超声振动系统具有多峰性，超声振动系统的频率搜索和频率跟踪非常困难。文中用实验的方法研究多峰振子与振动系统的电流电压相位和电流大小关系，以及工具头的横向尺寸与振动系统主峰频宽之间的关系。根据实验规律，文中采用相位和电流双参数对振动系统的谐振状态进行判别，并在20kHz超声塑料焊接机上进行频率搜索和频率跟踪实验，实验表明双参数频率搜索和跟踪的方法是可行。

Frequency searching and tracking for multimodal ultrasonic vibration system

In the high power ultrasonic application, it is difficult to search and track frequency of ultrasonic vibration system automatically as a result of the multimodal characteristic of ultrasonic vibration system. In this paper the relations between the multimodal vibration system and the phase of voltage and current of vibration system and the value of current, and the relation between transverse size of ultrasonic probe and bandwidth of the highest peak of vibration system, are studied with experimentation. On the experimental nile, the state of resonance of vibration system is identified by phase and current. The experiment of frequency searching and tracking has been done on the ultrasonic plastic welding machine operating at 20kHz, and the result shows that the method of frequency searching and tracldng with double parameters is valid.