Application of Phase Locked Loop Circuit for Ultrasonic Atomizer Driving Circuit

• Main Authors: Wei-shan Huang, 黃薇珊
• Other Authors: Chia-Chi Sung
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/00949972691563799604

碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 100 === Resonating frequency and phase of the ultrasonic transducer may change due to variation of temperature and loading and duration of working, etc. Resonating frequency and phase of the ultrasonic transducer varies so that the output power of the ultrasonic transducer might decrease. The purpose of this paper is to design a high power ultrasonic driving circuit module with dynamic frequency tuning and describes the concepts and manners in detail of each subtle circuit in this circuit module. This module can drive from hundreds of thousands to several millions Hz on the high power condition, and it has high electro-mechanical conversion efficiency. This circuit can drive transducers with resonance frequency between 500KHz to 2MHz. We are going to apply this circuit module to the ultrasonic atomization system. It was observed that the higher the driving frequency will cause the phase of ultrasonic transducer drift is more significant. An ultrasonic transducer is precisely set at resonating frequency by phase locked loop circuit. Phase locked loop circuit consists of the feedback of voltage and current, phase detector, low-pass filter and voltage control oscillator. Besides, we are going to observe and discuss the ultrasonic atomization system with phase locked loop circuit. It was observed that the phase of ultrasonic transducer with phase locked loop circuit can be controlled at about zero degree. Otherwise, the phase of ultrasonic transducer without phase locked loop circuit will increase due to temperature rise. It was observed that the transfer efficiency of ultrasonic transducer with phase locked loop circuit can be maintained 95% conversion efficiency. Otherwise, the transfer efficiency of ultrasonic transducer without phase locked loop circuit will decrease due to temperature rise.