High Frequency Induction Heating Power Supply Control Strategy

This thesis studies the control strategy of high frequency series resonant induction heating power supply, analyzes the changes of the circuit parameters and load characteristics in the power supply running process. In order to eliminate the impact of changes in load characteristics caused by the running process on resonant circuit, this thesis proposes a frequency tracking circuit based on SG3525and CD4046, by detecting and processing phase difference signal of load voltage and current to control the output frequency of SG3525, makes its output frequency closer to the circuit inherent resonant frequency. Therefore, it can ensure the resonance circuit always in a weak inductive state, the frequency tracking of the power supply is achieved, and the system reliability and effectiveness are improved.This thesis uses mathematical computing, software simulation and other methods to complete the whole design of the induction heating power supply, calculates the parameters of filter circuit, rectifier circuit, inverter circuit, resonant circuit, and selects specific chip. This thesis also analysis and designs the drive circuit.Combined with the common faults of the induction heating power supply running process, this thesis designs capacitive protection circuit, overcurrent protection circuit and overheats protection circuit, by detecting the fault signal in the power supply running process to control the action of the protection circuit to achieve the purpose of protection. And at last, the thesis verifies the effectiveness of the protection circuit by experiments.