Software Control Technology To Improve The Efficiency Of Free Induction Heating

Electromagnetic induction heating equipment is widely used in industrial,life and other field.During operation of electromagnetic induction heating equipment,load-replacement,or temperature,humidity and other environmental factor changing and circuit element aging,will change the inherent resonance frequency of the load circuit.If induction heating equipment can not adapt along with the changing of the inherent resonance frequency of the load circuit,the heating efficiency of the induction heating equipment will be reduced significantly.This paper studies a software control technology to solve the problem list above,which uses load detection feedback circuit and STM32 microcontroller to monitor and control the induction heating equipment,to ensure that the heating efficiency not change when the load changes.Software control technology includes hardware and control procedure.Firstly,a method of load and frequency detection is put forward by analyzing and calculating the working process of the inverter circuit of induction heating equipment.Secondly,in order to monitor and control the induction heating device in real time,the STM32 system board is designed,which is the carrier of the control procedures.Finally,load detection and feedback circuit,DC power supply and other auxiliary circuits are designed.In the aspect of software design,firstly function analysis is performed.Secondly,control procedures are realized by modular way.Control procedures include initialization procedure,load detection procedure,Fourier transform procedure,procedure of monitoring that load is removed and reloaded,key scanning procedure,temperature monitoring procedure,display and timing procedure.Finally,the modular procedure is connected to a complete control procedure.The test of software control technology is about peripheral circuits and system testing.Powered by 12V/50 HZ AC,DC power supply circuit is tested to supply DC 18 V,12V and 5V.When the input is a rectangular wave of 3.3V,the IGBT drive circuit is tested to obtain a 18 V output rectangular waveform.Powered by 12V/50 HZ,the load detection and feedback circuit is tested to get the detection and feedback signal.The system test was carried out under 220V/50 HZ.First of all,under the circumstances of the induction heating equipment with or without load,load detection function are tested,includes the generation of IGBT drive signal,acquisition function of the system board for external signal,the function of the program to obtain the number of waveforms.Next,when the induction heating device has a load of 430-pots filled with 2L water,the Fourier transform function and the normal heating function are tested,the heating efficiency is calculated.When the load of the induction heating equipment is unloaded or reloaded,the load monitoring function is tested.If the load is removed and then is reloaded,functions of detecting the pot and normal heating automatically are tested.The feasibility and correctness of the software control technology are verified by the experiments.