功率超声波电源频率跟踪系统设计

摘要

In order to solve the problem of resonant frequency drifting of a piezoelectric transducer, the design of a frequency tracking system for power ultrasonic generator based on the current RMS and the phase difference feedback was proposed. According to the electrical circuit module of the piezoelectric transducer, how the current RMS and the phase difference depend on the frequency of an ultrasonic generator was analyzed. The current TRMS and the phase difference were chosen as the two feedback parameters for the frequency tracking system. The corresponding controlling method and hardware were designed. Result obtained from a real ultrasonic generator using this designed frequency tracking system indicates that this frequency tracking system has improvement performance in both system stability and tracking accuracy. The tracking time is less than 70ms, and the frequency adjust resolution is 0.233Hz.%针对压电换能器谐振频率漂移的问题，讨论了一种基于电流有效值、相位差复合反馈的功率超声波电源频率跟踪系统的设计。根据压电换能器的电路模型，分析了电流有效值以及相位差与超声波电源工作频率间的关系；确定利用电流真有效值和相位差双参数进行反馈控制；并讨论了系统各部分的具体设计。实际的频率跟踪实验表明，该频率跟踪系统具有较好的稳定性和精度，跟踪时间最长不超过70ms，频率调整分辨率0.233Hz，满足了压电换能器频率跟踪的要求。