1 Induction furnace for the output power requirements of thyristor intermediate frequency power supply.

The output power of the thyristor intermediate frequency power supply must meet the maximum power of the induction furnace, and the output power can be easily adjusted. This is because the life of the induction furnace is usually damaged after smelting dozens of furnaces. The lining of the kiln is built, and the new kiln lining must be finished with a low-power oven. Usually the oven starts at 10-20% of the rated power and then increases the power by 10% at regular intervals until the rated power. In addition, in the process of the furnace, when the charge is melted, the composition of the charge must be tested, and during the test, the boiling of the charge is not drastic, and the intermediate frequency power supply must reduce the output power to keep the charge warm. In view of the above situation, it is required that the thyristor intermediate frequency power supply can be conveniently adjusted from the range of 10%-100% of rated output power. The diathermy for forging does not have a process of oven.

2 Induction furnace requirements for the output frequency of thyristor intermediate frequency power supply.

The relationship between the electrical efficiency of the induction furnace and the frequency is related. The output frequency of the thyristor intermediate frequency power supply can be determined from the electrical efficiency. For example, we call this frequency fo. The inductor is actually an inductor, and to compensate for the reactive power of the coil, a capacitor is connected across the coil, which forms the LC oscillating loop. When the output frequency f of the thyristor inverter is equal to the natural oscillation frequency fo of the induction furnace circuit, then the power factor of the loop is equal to 1 at this time. The maximum power will be obtained in the induction furnace. It can be seen from the above that the natural oscillation frequency of the loop is related to the values of L and C. Generally, the value of the compensation capacitor C is fixed, and the inductance L changes due to the change of the magnetic permeability of the charge, for example, when refining, The permeability coefficient μ of the cold furnace steel is very large, so the inductance L is large, and when the temperature of the steel is high to the Curie point, the magnetic permeability coefficient of the steel μ=1, so the inductance L is reduced, and thus the inductance of the induction furnace circuit is inherent. The oscillation frequency fo will go low and high. In order to make the induction furnace always get the maximum power during the melting process, this requires that the output frequency f of the thyristor intermediate frequency power supply can change with the change of fo, and the frequency is automatically tracked at all times.

3 Other requirements for thyristor IF power supplies.

This is because when the charge is in the smelting process, once the intermediate frequency power supply fails, it will be damaged in severe cases. Therefore, the thyristor intermediate frequency power supply is required to be reliable, and the necessary voltage limiting current limiting protection, overvoltage and overcurrent protection, and water cutoff are required. Protection, and other automatic protection devices. In addition, the thyristor intermediate frequency power supply requires a high success rate, and it is convenient to start and stop the operation.