Research On High-power Ultrasonic Power Supply And Application

With the development of ultrasonic technology in the field of industrial application, the demand of ultrasonic power supply which is the energy provider of ultrasonic equipment is becoming more and more urgent. The characteristics of ultrasonic power supply are analyzed in this paper based on the present research of ultrasonic power supply. And a kind of ultrasonic power supply based on digital control technology is designed with DDS technology and DC chopper technology.Firstly, the characteristics of rectifier side power adjusted technology, DC/DC power adjusted technology and DC/AC power adjusted technology are analyzed in this paper, and the DC/DC power adjusted technology is chosen as the power adjusted method of ultrasonic power supply. The main circuit topology of ultrasonic power supply based on DC/DC power adjusted technology is designed in this paper. Secondly, all kinds of traditional frequency tracking control method are introduced in this paper, such as the method of maximum current searching resonance frequency, phase-locked loop control method and the method of adjusting matching inductance. The shortcomings of long transition time and costing too many computing cycles of traditional frequency tracking method are analyzed, and a kind of variable step length frequency tracking method based on resonance frequency automatic identification is put forward in this paper. The frequency tracking method can effectively reduce the transition time of searching frequency, improving the dynamic response of ultrasonic power supply and guaranteeing the steady-state error of system is small. And the step switching condition of variable step length control is quantitatively analyzed in this paper. Thirdly, the characteristics of matching inductance in series and matching inductance in parallel are analyzed, and a suitable matching method is chosen in this paper. Furthermore, the power circuit and control circuit of ultrasonic power supply are designed in detail, and the frequency tracking control algorithm is written as a program which is embedded the control chip in this paper.Finally, the results of experiments proves that the ultrasonic power supply can adjust the output power and the variable step length frequency tracking method based on resonance frequency automatic identification can identify the resonance frequency of the ultrasonic transducer and keep it in resonant state. And the transition time of the proposed method is less than the traditional frequency tracking method. Therefore, the ultrasonic power supply has a good dynamic response, short transition time, and a low steady-state error.