Research On Temperature Control Method Of Medium Frequency Induction Heating

Induction heating, as a kind of industrial heating method, energy flow density,fast heating, high thermal efficiency, save energy, do not pollute the environment anda series of advantages, is widely used in roll surface hardening, bar diathermy, slabtempering, and other areas of the industrial production. Medium frequency inductionheating applied in oil drilling, geological drilling, coal mining, construction detectionin areas such as the required heat treatment of all kinds of high alloy steel pipe.The production process of hot extrusion tube, have very high demand on furnacetube temperature, not only requires the temperature error is very small and to achievethe core surface is uniform, it is important to control the temperature of the visible.However, the medium frequency induction heating tube is a complex physical process,it is difficult to establish accurate mathematical model.This paper analyzes the development and current situation of induction heatingpipe at home and abroad, and the development and current situation of intermediatefrequency power supply. According to the load characteristics of steel tube heating,analyses the structure of intermediate frequency power supply, differentcharacteristics of voltage type series resonant inverter and current type parallelresonant inverter, the voltage series resonance inverter. Compared the scheme ofpower adjusting and series resonant inverter of voltage type, select the DC Buckchopper modulation. For the complexity of intermediate frequency induction heatingsystem, the double closed loop cascade control used in temperature control system. Inthe double loop cascade control system, usually the outer and inner rings using PIDalgorithm is the same, because the induction heating temperature control system withnonlinear, strong interference, large lag characteristics, therefore, the inner loopadopts the conventional PID algorithm in power, the outer loop uses fuzzy algorithmtemperature, outer ring output value as the given value, in order to improve thetemperature control accuracy.In the MATLAB simulation software platform, the design of the fuzzy and PIDcascade control is simulated, and the PID cascade control simulation waveformcomparison. The simulation results show that the fuzzy and PID control, moresuitable for medium frequency induction heating temperature control system, and is feasible and effective. And the control method is applied to the production site of theanalysis, test results show that, the tube temperature to meet the requirements ofproduction process.