Research On Medium Frequency Induction Heating Power Supply Based On DSP&FPGA

According to the electromagnetic induction principle, the alternating current passes into the solenoid so as to generate an alternating magnetic field, then eddy current is generated by cutting the magnetic field where the artifacts heat using its resistance. Using this way, induction heating technology achieves the effect of heating. Heating metal materials induction heating power supply is not only the most efficient, fastest, but also low power consumption and environmental protection. Meanwhile, the induction heating power supply is also easy to control the temperature, has a good working environment, and can easily heat the artifacts with complicated shape. Therefore, the induction heating power supply is becoming a hot topic of research in domestic.At present, several problems such as low power factor, difficulty in starting, low success rate, limited power regulation and complexed control system and so on are existed in SCR medium frequency induction heating power supply. The solution of DSP and FPGA joint control, which makes the control system more intelligent, is formulated against the problom of complexed control system and limited power regulation. In order to solve the problem of low power factor, the digital phase-locked loop is designed. The magnitude of inverter angle can be controled below a tiny range by using fixed-angle control. Using this way, the power factor is improved with a large extent. For startup problems of SCR medium frequency induction heating power supply, auxiliary startup and sweep frequency startup are used to make it excited oscillation transformed self-excited oscillation. And then the success rate of startup is up to99%.Based on the existing traditional analog300KW parallel resonant medium frequency induction heating power, load characteristics, working processes, and the way of power adjustment control are analyzed in this topic. Then, the power supply is transformed into a digital one by using DSP and FPGA chip. The topic focuses on the control strategies and the way of power adjustment of traditional analog power supply and realizes the adaptive phase sequence phase-shifted full-bridge thyristor control mode. And the topic deeply analyzes the characteristics of the power load in the heating process and achieves a fixed angle control of inverter angle and a wide range of frequency tracking. Meanwhile, two kinds of control strategies for its different power adjustment modes are designed in this topic, so as to achieve the effect that the traditional power can not achieve. Then, the problems of power startup are analyzed and the way of auxiliary startup and sweep frequency startup is designed to solve this problem. At last, the power supply is debugged and passed the test; meanwhile, the relevant working waveforms are measured.