Research And Design Of Ultra-High Frequency Induction Heating Power Supply Based On SiC MOSFET

Induction heating is an energy-saving,efficient,safe and environmentally friendly advanced heating technology compared to traditional resistance heating or flame heating.Therefore,induction heating is widely used in various fields such as melting metals and heat penetration,quenching and bending of workpieces.After decades of advances and developments in power electronics technology,high-capacity,high-frequency,high-reliability induction heating power supplies have become the focus of research today.This article takes megahertz-scale LLC induction heating power supply as the research object.The new wide bandgap semiconductor SiC MOSFET device is used to study the turn-off loss of SiC MOSFET under time-sharing control and parallel control.It is valuable for the research of practical ultra-high frequency induction heating power supply.At the same time,phase-locked loop technology is indispensable in ultra-high frequency induction heating power supply.This paper realizes digital phase-locking function through FPGA and improves the performance of dynamic frequency division according to load resonance frequency variation,thus expanding the phase-locked range of digital phase-locked loop.The first chapter introduces the background and principle of induction heating power supply and the research status in high frequency field at home and abroad.Based on the introduction of related high frequency induction heating power supply topology,the research content and significance of this topic are analyzed.The second chapter firstly introduces the voltage induction heating power supply topology and its working principle.The load characteristics and advantages and disadvantages of the LC compensation circuit and the LLC compensation structure are compared and analyzed.Considering that the LLC structure does not require an external load matching transformer and it is easy to enhance the power supply capacity,and finally decided to use the LLC compensation circuit.Then,the two working sequences of time-sharing control and parallel control are introduced.The turn-off losses of power devices under time-sharing control and parallel control are compared by two theoretical methods,and the universe conclusions are obtained.The third chapter firstly introduces the FPGA-based digital phase-locked loop chip 74HCT297 and the traditional digital phase-locked loop structure.In view of the small phase lock range of the traditional phase-locked loop,this paper calculates the frequency of the input voltage signal in real time and updates it regularly.The phase-locked loop system adjusts the dynamic frequency division value in real time according to the change of the load resonant frequency to achieve the purpose of expanding the phase-locked range.In addition,this chapter also introduces the phase-locked peripheral circuit,the drive circuit and the chopper control circuit,and analyzes its working principle and design scheme.The fourth chapter introduces the main circuit design and the parameters and selection of key components in the SiC ultra-high frequency LLC induction heating power supply prototype system.Finally,the megahertz-scale induction heating power supply experimental platform is built.The fifth chapter first uses the PSIM software to simulate and compare the inverter circuit under parallel control and time-sharing control,and then executes megahertz-level induction heating power tests on the experimental platform,including multiple operating frequencies and two control methods working conditions.Finally,a 1kW/ 1MHz induction heating power supply was developed.The sixth chapter summarizes the research content of this article,and puts forward the follow-up outlook on this basis.