SCR&IGBT Electrolytic Copper Rectifier

Basic principle

The AC input voltage is transformed by a transformer to obtain low-voltage AC power, and then rectified by a thyristor to obtain the required output voltage and current. The control circuit samples the output voltage and output current, and controls the phase angle of the thyristor triggering conduction moment through phase control after closed-loop feedback, so that the output voltage or current remains stable.

System architecture

Input side: three-phase AC enters the rectifier circuit through a transformer. Rectification and voltage regulation: The AC power is converted into adjustable DC power through a thyristor rectifier circuit. Output side: After filtering and voltage stabilization, a stable DC current is output. Control unit: includes trigger circuit, feedback control circuit and protection circuit to accurately adjust the output voltage and current.

Key parameters

The input voltage is usually three-phase AC, the output voltage ranges from tens of volts to hundreds of volts, and the output current ranges from hundreds to tens of thousands of amperes.
There are two types of rectification: three-phase bridge and double reverse star, with 12 or 24 pulses, on-load tap changer and balancing reactor, inlet and outlet line mode and control mode, whether to match DC isolating switch and cooler, etc.

Rectification mode

Three-phase bridge rectification

Three-phase bridge rectification: Three-phase bridge rectification usually uses ordinary three-phase transformer, and the secondary winding is three-phase star or triangle connection. Rectification element: 6 thyristors (silicon control rectifiers) or diodes are used to form a three-phase full-wave rectifier bridge.

Double reverse star rectification

Double reverse star rectification is divided into with balancing reactor and without balancing reactor, that is, three-phase five-column type. A specially designed transformer is required, and its secondary winding is divided into two groups, each of which is three-phase star connection, and the phase difference between the two groups is 180 degrees. Rectification element: Each group of star-connected three-phase windings is half-wave rectified by thyristors (silicon control rectifiers) or diodes. In order to balance the current between the two sets of rectifier circuits, it is usually necessary to add a balancing reactor on the DC side.

How to choose

Three-phase bridge rectifier: The main output voltage is >300Vdc, and the power demand is moderate. Medium and high voltage, high power occasions, such as DC motor drive, power electronic equipment, etc.
Double reverse star rectifier: Output voltage <300Vdc. If the voltage is at the critical value of 300V, both methods can be selected. Industrial applications that require high current and low voltage, such as electrolysis and electroplating.