The Research On 10kHz/150kW Mid-Frequency High Power Induction Heater

Mid-frequency high-power induction heater is applied widely in industry, such as refining, casting, forging, diathermy, quenching, winding-pipe, sintering, thermolize, brazing and crystal growth and so on. Meanwhile, with the special heating characteristics, researching and developing the induction heater, which can operate above sonic frequency and high power, becomes the one of the focus of research work in this field.This dissertation stresses on the design of the main circuit and control circuit for 10kHz/150kW induction heating application. The old induction heater, with an analogy method and silicon control unit was renovated by means of MCU DS80C320 and IGBT devices. The formulae to calculate parameters of main circuit are derived, the equivalent circuit of the system and the equivalent model of the load established, the structure and principle of the control circuit analyzed in detail here. Based on the request of frequency tracing for the voltage sourced induction heating supply anovel phase shift strategy is proposed in the paper. Describes a kind of PWM PFM hybrid control method for voltage fed series resonance inductive heating and provides an experimental circuit. This method has the advantages of wide area of power modulation and little change of frequency. It adapts to the inductive heating of medium power and supply frequency. A method for implementation the Digital Phase Locked Loop (DPLL) applied to induction heating power simply is put forward in the paper .The process of implementing this method using DSP is presented also. The frequency tracking method based on DPLL, phase compensation method and starting of the induction heating power supply are analyzed. Experimental results verify the correctness of this method.This dissertation discusses new ways with the problems like high frequency operation, no load-matching transformer.By using Simulink4, product of Matlab, the simulation model of the frequency induction heater whose power adjusted by buck circuit is set up and results of general control strategy are presented as well as multiple-frequency control.