main circuit characteristics of 1.5T MF induction melting furnace solid state power supply:
(1) Integrated silicon controlled assemblies installed
SCR uses the latest stacked radiator assemblies, as shown below. This installation method makes the assembly and disassembly of SCR more convenient and scientific, and the circuit is more neat. When the silicon control is replaced, any silicon controlled element in the assembly can be replaced by loosing a top tightening bolt. The radiator assembly has a scale for fastening as a reference to ensure the correct compression force between SCR and radiator. Moreover, this installation method can reduce the volume of SCR assembly and increase the operation space in the gas cabinet.（2）Large capacity filter reactor
Filter reactor is very important to solid power supply, it has two functions. First, the output current of the rectifier becomes smooth and stable. Second, the growth rate of short-circuit current and the magnitude of maximum short-circuit current are limited when the inverter thyristor passes through short circuit. If the parameters of the filter reactor are not designed properly, the core material is not good or the manufacturing process is not up to standard, the reliability of the solid power supply will be greatly affected.
In order to ensure the reasonable parameters of the filter reactor, a filter reactor design software package is developed. When the software is designed, the working environment of the filter reactor is specially considered under the condition of parallel inverter. At the same time according to our production of solid-state power supply experience of more than ten years and compiled.
It can fully optimize the parameters of the filter reactor, in particular, it can analyze the variation of the parameters of the filter reactor in the range from 0 to 3 times the rated current. Ensure that the core is not magnetically saturated when the current through the filter reactor is 3 times the rated current. Because the current through the filter reactor is much larger than the rated current when the inverter thyristor passes through the short circuit of the solid power supply. If the core of the filter reactor is saturated, the filter reactor will lose its current limiting effect. Therefore, it is necessary to ensure that the filter reactor core will not be magnetically saturated when the current is greater than the rated current. Only in this way can the filter reactor have a good current limiting effect and ensure that the maximum short circuit current is limited within a reasonable range.
The silicon steel sheet of filter reactor adopts cold rolled high magnetic conductivity product. The copper tube is made of T2 extruded copper tube, which is wrapped with high strength mica tape.
In order to reduce the working noise of the filter reactor, the silicon steel sheet adopts a special fastening process, and a special absorbent material is also filled between the silicon steel sheet and the air gap.。
(4) output circuit of double voltage
In order to reduce the loss on the intermediate frequency transmission line, the compensation capacitor of the inverter is connected into a series of parallel voltage doubling (see left). This method can double the output voltage of the inverter. In this way, at the same output power, the output current becomes 50% of the original, thus reducing the loss on the if transmission line to 1 / 4 of the original.
（5）Large capacity compensated capacitor bank
In order to reduce the loss on the intermediate frequency transmission line, the compensation capacitor of the inverter is connected into a series of parallel voltage doubling (see left). This method can double the output voltage of the inverter. In this way, at the same output power, the output current becomes 50% of the original, thus reducing the loss on the if transmission line to 1 / 4 of the original.
