Induction heating technology has the advantages of high heating temperature, high heating efficiency, fast speed, easy control of heating temperature, easy mechanization, automation, and no air pollution. Now induction heating power supply has been widely used in metal melting, heat transfer, heat treatment and welding. Industrial process. According to the different power adjustment amount, the induction heating power supply has various power adjustment modes. The frequency modulation power adjustment is to change the output impedance of the inverter to change the output impedance of the inverter to achieve the purpose of adjusting the output power. The control of the power adjustment mode is relatively simple, and the operating frequency of the circuit can be directly controlled, and the power can be continuously adjusted. This article is based on the frequency modulation and power adjustment method, the heating power source controlled by the PWM control chip SG3525. The induction heating power supply designed in this paper is a series resonant full-bridge IGBT inverter power supply. The main circuit structure of the inverter is shown in Figure 1. The input adopts three-phase AC/DC uncontrolled rectification, and the output adopts a load series resonant full-bridge DC/AC inverter circuit. The voltage of the rectified output is filtered by the high voltage large capacitor C1, and the main switching devices Q1, Q2, Q3 and Q4 of the inverter are IGBTs, and D1, D2, D3 and D4 are anti-parallel diodes. Figure 1 main circuit structure The principle of FM control is to change the output impedance by changing the inverter switching frequency to achieve the purpose of adjusting the output power. The series resonance equivalent circuit diagram is shown in Figure 2. Figure 2 load equivalent circuit diagram Load equivalent impedance is Z=1/jωC+jωL+R; then Ic Logic,Logic Counters Dividers,Logic Fifos Memory,Logic Buffers Drivers Receivers Transceivers Shenzhen Kaixuanye Technology Co., Ltd. , https://www.iconlinekxys.com
Induction heating power supply using frequency control of SG3525
1 Introduction