The thyristor parallel circuit is a parallel intermediate frequency furnace. In the melting process, especially for the smelting materials such as aluminum and copper, the load is very light, and its power output is very small, which is closely related to the properties of the load, so the melting speed is slow and the heating is difficult. The thyristor series intermediate frequency furnace adjusts power by frequency modulation, so it is relatively little affected by the properties of the load. The whole process of melting almost keeps constant power output. Because of the series resonance, that is, voltage resonance, the inductive coil voltage is high, and the current is small. So the power loss is small.
Because of the series inverter circuit, the power factor is high and the harmonics are small. This can save users a large amount of expenditure, but also the power sector to promote the promotion of advanced equipment.
When the series inverter intermediate frequency furnace works, the rectifier always works in the state of full conduction, and the output power of the inverter circuit is changed by controlling the frequency of the inverter trigger pulse. And the load current is sine wave, so the series inverter power supply will not pollute the power grid seriously with high order harmonics, and the power factor is high. But the parallel inverter can not realize the operation of one-towing and two-automatic power regulation, because the power regulation of the parallel inverter power supply can only be achieved by adjusting the output voltage of the rectifier bridge. When the parallel inverter rectifier bridge works at a low voltage and the rectifying conduction angle is very small, the power regulation can only be achieved by adjusting the output voltage of the rectifier bridge. The power factor of the equipment will be very low, and the parallel inverter load current will be square wave, which will seriously pollute the power grid. If The range of power regulation is very narrow by adjusting the inverse voltage angle of the inverter, so the parallel inverter power supply can not be operated in one drag and two operation.
