| According to the feature of high efficiency, high speed, high heating temperature,and automation,induction heating power supply is widely used in metal heat treatment.With the rapid development of power electronic devices and power electronic technology, the induction heating power supply is developping continuously towards the direction of high power, high frequency.And the control circuit is also changing from analog to digital control circuit. The induction heating power supply technology is using the principle of electromagnetic induction and the eddy current principle.The alternating current passes into the solenoid to generate an alternating magnetic field,then eddy current is generated by cutting the magnetic field where the artifacts heat using its resistance.The point of this thesis is to realize the digitization of the traditional 250 kw parallel resonant induction heating power supply. IGBT is selected as the main power device.The system based on dual control core of the ultrasonic frequency induction heating power supply is proposed.In this paper, the important principle of the induction heating power supply system has described in details.By making comparison of different control modes,the reasonable one is selected.In order to insure the control precision,the double closed-loop control method and improved PI algorithm based on DSP are proposed.FPGA is used to generate the drive signal. The reasonable sampling circuit and protect circuit are designed to improve the real-time of the whole remote control system.The real time monitoring of the whole parameters of induction supply system is realized by HMI system which also makes the system more intelligent.The overall framework of this thesis is as follows: Firstly, the basic principle of induction heating supply system is introduced.The requirements of this study has been put forward by making comparison of the development of heating system research situation at home and abroad. Secondly, it analyzes the principle of whole power system, determines the control strategy and model and puts forward the overall solution.Thirdly, it introduces the implement method of whole control system including DSP and FPGA system structure. The chip features of DSP and FPGA are shown on details. The essential function of this system is designing the program codeof two processors, realizing the PLL, proposing the start-up mode solving scheme,designing the sampling circuit and protection circuit,and so on. Finally, with the help of Tsinghua power electronics company, the whole supersonic frequency induction heating power supply system is made experiment with the equipment to verify the feasibility of the control scheme and safety stability of the system. And the experiments have shown that the control strategy which is researched in this thesis is reasonable. |
