Induction heating power supply is widely used in metal heat treatment, quenching, annealing, diathermy, melting, welding, heat sheath, semiconductor material refining, plastic heat bonding, baking, and purification, etc. The conductor itself is heated by the induced current under the action of high frequency magnetic field.
Compared with furnace heating, combustion heating, or electric wire heating, induction heating has the advantages of significant energy saving, non-contact, fast speed, simple working procedure, and easy to realize automation.
Induction heating power supply is mainly composed of rectifier unit, inverter unit, resonant output unit and inductor.The rectifier unit converts the power frequency three-phase AC voltage into dc voltage.The inverter unit energy is converted into high frequency energy from thousands to hundreds of kilohertz.One end of the resonant output unit is connected to the inverter, and the other end is connected to the inductor. Through isolation and impedance matching, the resonant method generates strong high-frequency current in the inductor.When heated, the inductor induces a high frequency current in the workpiece, so that the conductor is heated rapidly.
In the early induction heating equipment, the form of the device is determined by the high frequency inverter required by the inverter unit, which has experienced the development process from the electron tube and thyristor to the IGBT widely used at present. In the current mainstream IGBT induction heating products, there are still many differences in the circuit and structure. From the rectifier unit, there are controlled rectifier mode and uncontrollable rectifier mode. From the point of view of the inverter unit, there is pulse width modulation inverter mode and chopper voltage regulation inverter mode; It can be seen from the resonant output unit that there are parallel resonant mode and series resonant mode. Various circuits and structures vary in efficiency, power factor, reliability, and other performance.