The working principle of 2021 new induction melting furnace

1. From the schematic diagram of the main circuit of the офтобҳои обгузарӣ above, it can be seen that the power supply part of the induction melting furnace is composed of a power supply contactor and a three-phase AC absorption; the rectifier part is composed of a three-phase fully controlled rectifier bridge composed of multiple thyristors , It enables the output power of the induction melting furnace to be continuously adjusted from 0.1Pn (Pn represents the rated power) to Pn. When it is shut down or fails and stops running, the rectifier can be converted from the rectifier working state to the inverter working state, so that it is mainly stored in DC The energy in the intermediate circuit is fed back to the power supply network. In order to protect the rectifier thyristor, a fast fuse and DC reverse overvoltage protection are also set in the circuit.

The DC intermediate circuit is essentially composed of a water-cooled choke with an iron core. Its function is to filter the pulsating DC output of the rectifier and suppress the influence of the intermediate frequency voltage on the power grid. When the load is short-circuited, it also plays a role in preventing the current from rising too fast.

The inverter is composed of a single-phase full-control inverter bridge composed of multiple fast thyristors. By alternately triggering the thyristors, the current is output to the input terminals u and v of the parallel resonant load in a changing direction at an intermediate frequency.

In addition, the main circuit of the induction melting furnace also includes AC and DC starting circuits.

2. Control circuit

The circuit in the main circuit principle diagram is the control circuit of the induction melting furnace. For this part, a more detailed control and adjustment block diagram is given. It can be seen from the figure that the rectifier of the induction melting furnace is controlled by two units: a rectifier regulator and a rectifier trigger. Variable pulse amplifier to control.

The fault monitoring and protection of the whole induction melting furnace are controlled by electronic protection and inverter monitoring, and the signals of current and voltage are specially completed by the signal feedback board.

The start of the entire induction melting furnace is completed by vibration control.

The coordination of all the above units is controlled by a programmable controller (PLC).