Research On LCL Resonant Induction Heating Power Supply Based On Controlled Switched Capacitor(SCC)

Induction heating technology is widely used in industrial,civil,and commercial fields due to its superior performance advantages such as good heating effect,high efficiency,energy saving and environmental protection.The output characteristics of the induction heating power supply are very sensitive to load fluctuations,and the physical characteristics of the magnetic components change significantly with temperature,especially when the temperature reaches the Curie point,the magnetic permeability of the magnetic components will undergo abrupt changes,so in smelting and waste gas treatment When the heating temperature reaches the industrial scene of the Curie point,the normal operation of the induction heating power supply will be greatly affected,and the power supply may even be damaged.Traditional researches use frequency conversion to achieve frequency modulation control,and large frequency fluctuations will reduce the utilization of magnetic components,increase the loss of magnetic components,increase the difficulty of device selection,and also affect the volume and cost of the system.Therefore,this paper proposes a LCL induction heating power supply based on a new type of controllable switched capacitor(SCC),which can adapt to the fluctuation of induction heating load characteristics without changing the operating frequency.This article first introduces the topological structure of the new controllable switched capacitor SCC,and analyzes its working principle in detail,establishes a mathematical model for it,and derives the calculation formula of SCC equivalent capacitive reactance.Through quantitative analysis and verification,the feasibility of the SCC topology as a variable capacitive reactance is verified.Secondly,the new topology of the SCC-LCL induction heating power supply proposes an automatic tuning control that adapts to the change of the equivalent inductance of the load.Firstly,the working principle of automatic tuning of the SCC-based LCL induction heating power supply is analyzed in detail,and its working mode is described in detail;finally,the effectiveness of automatic tuning control and frequency tracking protection control is verified by simulation.Third,based on the automatic tuning characteristics of the induction heating power supply,a power adjustment control that adapts to the change of the equivalent inductance of the load is proposed.First,a detailed analysis of the output characteristics of the LCL induction heating power supply shows that its output characteristics are sensitive to the change of the load equivalent capacitive reactance,and its output current is the largest at resonance,and its value is related to the inductance matching ratio and cannot remain stable.Furthermore,the segmented power regulation control of the LCL induction heating power supply based on SCC is proposed.When the maximum output power meets the power regulation,the current closed-loop control is used to maintain the power regulation control;when the maximum output power does not meet the power regulation,the rectifier circuit control is used to achieve Power adjustment control.The simulation experiment verifies the effectiveness of the power adjustment control strategy of the LCL induction heating power supply based on SCC.Finally,the hardware design and software design of the proposed LCL induction heating power supply were carried out,and a low-power experimental prototype was built to further verify the effectiveness and feasibility of the SCC-based LCL induction heating power supply topology and control strategy for fluctuating load characteristics.