| Induction heating power supply is widely used in industrial and civilian applications for its high efficiency, high heating speed, flexible control and clear heating conditions. Focusing on the existing problems and the hot researching emphasis, this paper deeply studies the inverter control circuit and inverter over-voltage, over-current protection of parallel IGBT induction heating power supply. The main productions and conclusions are as the following:Firstly, solid-state induction heating of the background and current research problems is analyzed, while the characteristics of solid state induction heating is made a detailed summary.Secondly, the dual relationship of the series and parallel inverter circuit is compared on the advantages and disadvantages, and then analyzed the principle of parallel inverter and its various working condition, reaching the conclusion that parallel inverter only work in small capacitive state is safe and reliable.Thirdly, based on the principle of PLL, the paper researches and designs of a parallel inverter control circuit, through combining phase-locked loop with PI regulator technology bring about that the inverter operating frequency is automatic tracked and power factor control is fixed. Sampling, delay of the device turning on and off and other causes is made time compensation, and solve the problem of overlap angle being manually adjusted. The contol strategy is taken MATLAB simulation and its hardware is designed based on the CD4046, and then it is conducted prototype testing. The results show that control circuit is I have designed has the advantages of precise control and rapid response.Finally, this paper presents a simple and practical inverter over-voltage, over-current protection measures to effectively address the problem the parallel inverter over-voltage protection. In addition, the paper also designs the circuit of the drive pulse lost and phase exception protection. |
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