ABB 5SHY3545L0016 Automatic industrial control module

IGCT is in the same vein as SCR in the rectification process, SCR is the abbreviation of Silicon Controlled Rectifier. Thyristors have one-way, two-way, turn-off and light control several types.

It has the advantages of small size, light weight, high efficiency, long life, easy control and so on. It is widely used in controlled rectifier, voltage regulation, inverter and contactless switch and other automatic control and high-power power conversion occasions. Unidirectional thyristor is a kind of controlled rectifier electronic component, which can be turned off from off to on under the action of external control signal, but once it is turned on, The external signal cannot be turned off, and it can only be turned off by removing the load or reducing the voltage at both ends. Unidirectional thyristor is a four-layer, three-terminal semiconductor device composed of three PN junction PNPN. Compared with the diode with one PN junction, unidirectional thyristor is controlled by the control electrode current. Compared with a triode with two PN junctions, the difference is that the thyristor has no amplification effect on the control electrode current. Bidirectional thyristor has the characteristics of turning on and off in two directions. Bidirectional thyristor is essentially two anti-parallel unidirectional thyristor, which is a semiconductor device composed of four PN structures formed by NPNPN five layers of semiconductors and has three electrodes. Because the structure of the main electrode is symmetrical (all from the N layer), its electrodes are not called anode and cathode like unidirectional thyristors, but the first electrode A1 that is very close to the control is called the second electrode A2.

The main disadvantage of bidirectional thyristors is the low ability to withstand the voltage rise rate. This is because when the bidirectional thyristor is switched on in one direction, the carriers in each layer of the silicon wafer have not returned to the position of the cutoff state, and corresponding protection measures must be taken. Bidirectional thyristor components are mainly used in AC control circuits, such as temperature control, light control, explosion-proof AC switches and DC motor speed regulation and commutation circuits. The thyristor is always in the open state above the maintenance current, the turn-off current is high, the control is difficult, and the turn-off speed is slow. In the inverter link, SCR has excellent performance in LCI (load commutated inverter), which can achieve large power, high voltage and large current. Diode (uncontrolled rectifier device) and SCR (semi-controllable) rectifier do not require PMW to meet the two-quadrant inverter work, PWM requires IGBT (full control) and other devices.