中文摘要：

频率跟踪是超声波电源的一个非常重要的特性。针对传统超声频率跟踪系统存在的频率跟踪范围狭窄、失锁、易出现误跟踪等缺点，提出了一种新颖的基于模糊控制结合直接数字频率合成（Fuzzy—DDS）的复合频率跟踪控制策略。该策略通过Fuzzy控制器进行频率粗调，通过DDS精确跟踪电路进行频率的精确跟踪。试验表明，基于这种控制方法的超声波电源具有频率跟踪速度快、跟踪准确的优点，并可以实现振动系统的稳定、高效运行，提高了电源效率。

英文摘要：

Frequency automatic tracking is a very important characteristic of ultrasonic power supply. Some weaknesses are found in traditional ultrasonic frequency tracking system,such as the narrow scale of frequency tracking and losing phase-locked and the tendency to track frequency mistakenly,etc. This paper proposes a novel hybrid control strategy which combines fuzzy control with DDS. The strategy includes coarse tracking by Fuzzy controller and precise tracking by accurate tracking circuit of DDS. The results show that the ultrasonic power supply using Fuzzy-DDS controller has the advantages of quick and accurate frequency tracking,and can make the vibrate system work stably and efficiently, thus it can improve power efficiency.