Development and use of IGBT medium frequency induction heating furnace

With the update of technology, IGBT medium frequency induction heating furnace is increasingly accepted by customers. The new induction heating power supply is mainly composed of inverter, resonance unit, transformer and inductor. The inverter is a high-frequency power supply that converts power frequency current into thousands and hundreds of kilohertz. One end of the resonant cloud and the transformer are connected to the inverter, and the other end is connected to the inductor to convert the high voltage into an isolated low voltage. Impedance matching is performed, and a strong high-frequency current flows through the inductor during heating, generating an induced current in the workpiece, so the workpiece is heated at a high speed. The emergence of new products has advantages but also some problems, but these problems also show that IGBT medium frequency induction heating furnaces have broader room for development and improvement.

Principles and advantages of IGBT medium frequency induction heating furnace power supply control:

1) IGBT intermediate frequency power supply is a constant power output power supply. It can reach full power output by adding a small amount of material and remains unchanged, so the melting speed is fast; because the inverter part adopts series resonance and the inverter voltage is high, all IGBT The intermediate frequency is more energy-saving than the ordinary thyristor intermediate frequency; the IGBT intermediate frequency uses frequency modulation to adjust the power, and the rectifier part adopts full-bridge rectification, inductor and capacitor filtering, and always works at 500V, so the high-order harmonics generated by the IGBT intermediate frequency are small and the pollution to the power grid is low. .

2) IGBT intermediate frequency power supply is an intermediate frequency induction melting furnace using series resonance. Its inverter device is a new IGBT module (insulated gate bipolar transistor, produced in Germany). It is mainly used for melting ordinary carbon steel. , alloy steel, cast steel, non-ferrous metals. It has the advantages of fast melting speed, energy saving, and low harmonic pollution.

3) The energy-saving IGBT medium frequency induction heating power supply can save 15%-25% of energy than the traditional thyristor medium frequency power supply. The main reasons for energy saving are:

A. The inverter voltage is high, the current is small, and the line loss is small. This part can save about 15% of energy. The inverter voltage of the energy-saving IGBT transistor intermediate frequency power supply is 2800V, while the inverter voltage of the traditional silicon controlled intermediate frequency power supply is only 750V and the current is small. Nearly 4 times, the line loss is greatly reduced.

B. The power factor is high, the power factor is always greater than 0.98, and the reactive power loss is small. This part saves 3%-5% energy than the thyristor intermediate frequency power supply. Since the energy-saving IGBT transistor intermediate frequency power supply adopts a semi-controlled rectification method, the rectifier part does not adjust the thyristor conduction angle, so the power factor is always greater than 0.98 during the entire working process, and the no-power loss is small.

4) Constant power output: The thyristor intermediate frequency power supply adopts voltage regulation and power regulation, while the energy-saving IGBT transistor intermediate frequency power supply adopts frequency regulation and power regulation. It is not affected by the amount of charge and the thickness of the furnace lining, and maintains constant power output during the entire smelting process. Especially when producing non-magnetic materials such as stainless steel, copper, aluminum, etc., it shows its superiority, with fast melting speed, less burning loss of charge elements, and reduced casting costs.

5) High-order harmonic interference: High-order harmonics mainly come from the burr voltage generated by the thyristor during the voltage regulation of the rectifier part, which will seriously pollute the power grid and cause other equipment to fail to work normally. The rectifier part of the energy-saving IGBT transistor intermediate frequency power supply adopts In the semi-controlled rectification method, the DC voltage always works at the highest level without adjusting the conduction angle, so it will not produce high-order harmonics, pollute the power grid and transformers, the switch will not generate heat, and will not interfere with the operation of other electronic equipment in the factory.