Design Of The Power Ultrasonic Supply Based On FPGA

Ultrasonic generator is a kind of equipment that can generate ultrasonic energy and transfer the energy to the ultrasonic transducer. Once getting the ultrasonic energy, the ultrasonic transducer will work at resonant state. Since ultrasonic technique was invented, studying at ultrasonic power supply is always a popular subject. Frequency-tracking control system and power condition control system are the two most important problems. The traditional systems basically composed of analog devices and some dependent digital devices. The structure of the circuit is simple. But it has lots of defects, including bulky volume, low precision and poor stability.FPGA (Field-Programmable Gate Array) has overcome the defects above-mentioned. It has been widely used in digital circuit design. The main topic of this thesis is to complete the two control systems and further to found the whole circuit of the ultrasonic power supply. This paper mainly include following:In the first half of the paper, the ultrasonic vibration system is analyzed detailed, which include the reactance characteristic of ultrasonic piezoelectric transducer analysis and the matching circuit analysis between the ultrasonic generator and ultrasonic transducer. Then the principle of frequency tracking and power condition are introduced.In the middle part of the paper, the main circuit and matching networks circuit are designed. IGBT switching device is carried out a detailed introduction.Then one of the focus tissues is following. It's about the design of the ultrasonic generator's two control system based on FPGA. In this design of systems, frequency tracking control system bases on the principle of phase-locked-type frequency-tracking. DDS (Direct Digital Frequency Synthesizer) is the core of this system. Power condition control system is composed of PWM generator and PID controller and this system can make the Buck-type chopper circuit's output stable.Using the modelsim software, we can simulate the control system of the ultrasonic generator. Through the results of the simulation, we can find that frequency tracking system and the power conditioning system totally get the function we want.