超声焊接全状态频率跟踪算法

Full-state frequency tracking algorithm of ultrasonic welding

超声金属焊接负载重且变化剧烈,易导致换能器出现无阻性点和电源频率误跟踪。基于梅森等效模型,提出一种能同时计算出谐振频率与反谐振频率,避免误跟踪的全状态频率跟踪算法。存在阻性点时,利用3个不同发波频率及其对应的相位差,算出跟踪目标频率;当换能器处于无阻性点状态时,把跟踪目标变为相位差最小点,从而实现全状态频率跟踪。通过仿真软件对算法进行仿真,算法能有效避免误跟踪。焊接试验结果表明,能较易实现谐振频率和反谐振频率的频率跟踪,在无阻性点的工况下焊接过程平稳。

Ultrasonic metal welding loads are heavy and vary drastically,which can easily lead to non-resistive frequency state in the transducer and supply frequency mis-tracking.This paper proposes an full-state frequency tracking algorithm based on the Mason equivalent model that can simultaneously calculate the resonant and anti-resonant frequencies to avoid mis-tracking.When the transducer has resonant frequency and anti-resonant frequency,the target frequency is calculated by using three different frequencies and their corresponding phase differences in welding process;when transducer is in non-resistive frequency state,the tracking target is changed to the point with the minimum phase difference,thus achieving full-state frequency tracking.The algorithm was simulated by simulation software and it was concluded that the algorithm can avoid the frequency mis-tracking phenomenon.The welding test results show that the frequency tracking of resonant frequency and anti-resonant frequency can be easily achieved,and the welding process is smooth when the transducer is in the non-resistive frequency state.