Study On Phase Tracing For Supersonic Frequency Induction Heating Power Supply Using IGBT

Using the principle of electric heating by electromagnetic induction the induction heating power supply has many merits, such as the high heating efficiency and speed, the good controllability, and easy to mechanical and automatic implementation etc. It has been extensive used in so many trades, which by way of advanced technology and basic technology.The parallel resonance supersonic frequency induction heating power supply uses IGBT in the inverter circuit, and then it can operate on different state(capacitive, perceptual, resonance). On the perfect state, the traditional technique of phase tracing adjusts the operating frequency to make the power supply operate on resonance. But in fact, there is direct influence on the operating state caused by the IGBT's current change time and the variety shaping time of voltage signal. This paper introduces the working principles of induction heating power supply, analyzes major factors which effect the phase tracing in operating mode. A control system which based on DSP was designed to implement the negative voltage control.This system use TMS320F240C as the CPU. Sample the negative voltage on the diode series with IGBT by Peak hold switch circuit, and cut-in A/D module in the DSP, compared with setting value. Then digital PID adjusting instrument can adjust the negative voltage exactly.The experimental result indicates that the part of the negative voltage control improves the situation that the operation state of the induction heating power supply depends on the IGBT's current change time and the variety shaping time of voltage signal and the diode series with IGBT could be damaged by the oversize reverse recovery loss, increases the dependability of the induction heating power supply.