Digital Research On High Power Induction Heating Power Supply Based On MOSFET

This paper briefly introduced the basic principle and the development trend of induction heating technology, as well as analyzed power regulating methods of induction heating power supply. It can be proved that power regulation in the commutate side is propitious to enhancing the frequency and power level of high-frequency induction heating power supply. So this paper chose uncontrolled rectifying circuit and Buck choppering power regulation method as the subject investigated.Besides, it analyzed the characteristics of MOSFET and chose transformer power combination which has a relatively low demand of inverter circuit consistency.The traditional analog simulation phase-locked loop based on the CD4046 is mostly used in the induction heating power supply frequency tracking channel, but the traditional simulation phase-locked loop has some shortcomings, such as the narrow frequency track scope, the slow dynamic response, the bad reliability, the need of using auxiliary circuit to realize dead time and so on. A method of implementing Digital Phase-Locked Loop (DPLL) based on DSP is put forward in this paper, according to the mathematics model of Phase- Locked Loop (PLL). The algorithm of the Digital Phase-Locked Loop(DPLL) and the software and hardware of the design have carried on the detailed elaboration in the paper. The power closed-loop control system has been designed, the power control of the induction heating power supply transform to the Buck chopper voltage control. Closed-loop control system with deadline current negative feedback has been designed,according to the induction heating's characteristic. The realization method based on the DSP software and hardware is elaborated in detail.Because of the low current level of MOSFET, it needs to expand power capacity by transformer power combination.An induction heating power supply is designed based on theoretical analysis. The power of which are 60kW with the frequency 10 kHz for the chopper and 300 kHz for the inverter. The special DSP chip of TMS320LF2407A which produced by TI Company is used as main controller of the power to simplided the system.At last,the simulation, software,hardware and experimental results are all presented in this paper.