Rectifier element (thyristor)
In simple terms, a rectifier converts single-phase or three-phase sinusoidal alternating current through a rectifier element into a stationary, adjustable single-direction DIRECT current. Its realization condition mainly depends on the rectifier tube, thyristor and other components through the rectification to achieve. In addition, there are many rectifier devices, such as: turn-off thyristor GTO, reverse conduction thyristor, bidirectional thyristor, rectifier module, power module IGBT,SIT,MOSFET, and so on, here only discuss the thyristor.
Thyristor is also called thyristor, usually called thyristor. It is a kind of power semiconductor device, because of its high efficiency, good control characteristics, long life, small size and other advantages, since the last century 60 long generation, has gained rapid development, and has formed an independent discipline. Thyristor development to today, in the process has been very mature, better quality, the rate of finished products greatly improved, and to high voltage and large current development.
Application of thyristor:
1. Controllable rectifier
As diode rectification, can be the ac rectification for DC, and in the case of constant AC voltage, easy to control the size of the DC output voltage is controllable rectification, to achieve AC - variable DC
2. AC voltage regulation and power regulation
The switching characteristics of the thyristor are used to replace the old contact regulator, induction regulator and saturation reactor regulator. In order to eliminate the high harmonics generated by the thyristor AC regulator, a zero crossing trigger is developed to realize the stepless regulation of load AC power, namely the thyristor regulator. Communication -- variable communication.
3. Inverter and frequency conversion
Dc transmission: the three-phase high-voltage AC rectifier to high-voltage DC, long-distance transmission by high-voltage DC to reduce loss, increase the stability of the power network, and then by the inverter dc high-voltage inverter to 50HZ three-phase AC.
Dc - AC Medium frequency heating and ac motor frequency control, series speed control and other frequency conversion, AC - frequency variable AC.
4. Chopper voltage regulation (pulse voltage regulation)
Chopper voltage regulation is the transformation between DC - variable DC, used in the city tram, electric locomotive, battery truck, forklift (forklift), electric cars, high frequency power supply for edM.
5. Contactless power static switch (solid state switch)
As a power switch element, instead of contactor, relay used for high switching frequency occasions.