Structure Optimization And Numerical Analysis Of High Frequency Induction Heating Device

As a non-contact heating equipment,high-frequency induction heating equipment has a series of advantages,such as high heating efficiency,good working environment,energy saving and environmental protection.It is widely used in quenching and melting of metal parts.As a non-metallic material,iron-based catalyst is mainly produced by traditional thermal melting method,which has the disadvantages of low yielding rate and quality.But its composition uniformity and catalytic activity are greatly improved in the high-frequency induction heating process.In addition,there is a problem of low control precision in the high-frequency induction heating device in industrial application.In view of this situation,combining with digital and intelligent control technology to optimize the internal circuit structure and designing a set of high-frequency induction heating device for non-metallic material have guiding significance for further study in the future.With the 4kW/250 kHz high-frequency induction heating device as the research object,the system structure and the working principle of each part were introduced in this thesis.Then the operating characteristics of different circuit types that system contains were compared and analyzed,determining the whole design of system.Single-phase,uncontrollable,bridge pattern rectifying and capacitance filtering were adopted to obtain the DC voltage in the main circuit,and the series resonant inverter circuit composed of MOSFET power switching device was selected to carry out the inversion process,which connects the isolation transformer to the load at the output end.The pulse width modulation method was used to regulate the power in the control part,when the load operating frequency was tracked to keep it in the resonant state.And the digital phase-locked loop and fuzzy PID controller based on ATmega128 MCU were designed.Then the parameters of the main circuit and the circuit structure of the control modules were determined according to the given technical specifications.The program flow chart of the frequency tracking module and the power control module were also given.Finally,a simulation model of high-frequency induction heating system was established in the simulation environment of Simulink,and the waveform of output voltage and currentwere observed.On the other hand,the finite element model of the system load was established by ANSYS software according to the mathematical model and the boundary conditions obtained by the correlation theory of electromagnetic field and temperature field,then numerical analysis was carried out to observe the temperature distribution of materials under different working conditions.The simulation results showed that the waveform of output voltage and current of the system kept the same phase relation at different phase-shift angle,which indicated that the phase-locked loop could track the resonant frequency effectively and the rationality of the design was validated.The higher the power supply frequency,the faster the temperature rise of the materials,the greater the temperature difference between the surface and the core,the more obvious the skin effect.In addition,the system heating efficiency was the best when the power supply frequency was 200 kHz to 250 kHz.