Research Of IGBT Induction Heating Power Supply Based On DSP

Based on the thermal effects, induction current can heat the surface of the work piece, make the surface heat fast and then refrigerate quickly. This modern industrial quenching technology is called induction heating surface hardening. After quenching, the heart still keep the toughness while the surface changed high hardness and wear resistance. The core of the quenching technology is the induction heating power supply.In this paper, an intermediate frequency power supply in 20kHz/10kW is designed, which can be used in the heating of axle and gear. In the power supply, a three-phase uncontrolled rectifier and the series resonance inverter was applied. Advanced high-power insulated gate bipolar transistors used as the inverter switching device. The TI's DSP chip TMS320F2812 used as the control chip. The whole induction heating power supply especially the digital frequency tracking and power control were designed.Firstly, the principles of the series power supply system were introduced, the status of power switch device IGBT at three working circumstances:inductive, resonant, capacitive was concretely analyzed. On the basis of IGBT high loss when shut off, capacitive phase-shifted PWM power modulation was designed. Then the principle of capacitive phase-shifted PWM power control was introduced. The feasibility of power control was confirmed through the MATLAB/SIMULINK.On the hardware circuit side, the system of TMS320F2812, the sampling circuit and the driving circuit of IGBT were designed. On that basis, the software phase lock loop and power phase shifting PWM control were programmed, the prototype and its overall debugging were completed.Experimental results verified the correctness of the software phase lock program, realized the fast frequency automatic tracking the control; generated the adjustable phase shift of driving pulse, realized the close loop power control.