Research on the frequency automatic tracking in ultrasonic power supply based on fuzzy-DDS

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 direct digital frequency synthesis(DDS). The strategy includes coarse tracking by Fuzzy controller and refined tracking by 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.