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Series intermediate frequency induction furnace

The series intermediate frequency furnace adopts half-bridge rectification and series inverter technology, which can realize one power supply to supply power to multiple electric furnaces and achieve high power factor operation. There is no need for reactive power compensation device and harmonic elimination device, and the induction coil current is small.

Introduction to series intermediate frequency furnace
1. The working principle of the series intermediate frequency furnace is to apply the alternating current generated by the intermediate frequency power supply to the metal material through the inductor, causing it to generate an induced current, thereby achieving the purpose of heating. The advantages of the series intermediate frequency furnace are fast heating speed, high efficiency, uniform heating, and high control accuracy. It is suitable for heating metal materials of various specifications and materials.
2. The oscillation circuit used in the series intermediate frequency furnace circuit is connected in series with L, R and C. The load circuit of the intermediate frequency furnace presents low impedance to the power supply and requires a voltage source to be powered. Therefore, the end of the rectified and filtered DC power supply of the series intermediate frequency furnace, A large filter capacitor must be connected in parallel. When the inverter fails, the surge current is large and protection is difficult.
3. The operating frequency of the series intermediate frequency furnace must be lower than the natural oscillation frequency of the load circuit, that is, an appropriate ta time should be ensured, otherwise commutation failure will occur due to the direct connection of the upper and lower bridge arms of the inverter.
4. Series intermediate frequency furnaces usually use a series resonant circuit, that is, the inductor and capacitor are connected in series to form a resonant circuit. At resonance, the current in the inductor is maximum, resulting in efficient heating. The control system of the series intermediate frequency furnace can achieve precise control of the heating process, including heating temperature, heating time, heating speed and other parameters.
5. The input voltage of the series intermediate frequency furnace is constant, the output voltage is a rectangular wave, and the output current is approximately a sine wave. The commutation is performed after the current on the thyristor crosses zero, so the current always leads the voltage by an angle φ.

 Operation mode of series intermediate frequency furnace
The operation mode of the series intermediate frequency furnace adopts one-to-two. One-to-two means that one set of rectifier power supply drives two sets of inverter devices to operate. It can also be operated independently by any set of devices to supply power to furnace No. 1 and No. 2. Dual power supply, one-to-two. Function, especially suitable for large-scale continuous production of small and medium-sized castings. Any one electric furnace can perform high-power melting operations, and the other furnace can be kept warm or preheated the cold furnace. The power can be distributed as needed. The total power used by the two electric furnaces is constant. remains unchanged, that is: total power P total = P1 + P2.
The two electric furnaces of the series intermediate frequency furnace continuously alternate melting and insulation casting, and operate simultaneously, so that the power supply can always operate at full power. This working method has one power supply and two furnaces working, which greatly reduces the capacity of the transformer. The two electric furnaces of the series intermediate frequency furnace can cast at the same time or continuously supply molten steel for casting. The power of the two furnaces can be distributed arbitrarily, and the start-up rate is 100%.