What is the principle of thyristor, it has those roles in the circuit.

Principle: thyristor in the process of work, its anode (A) and cathode (K) and power supply and load connection, composed of the main circuit of the thyristor, thyristor gate pole G and cathode K and the control of the thyristor connected to the device, composed of the control circuit of the thyristor.

There are three main roles:

1 Controlled rectification role:

One of the roles of the SCR is controlled rectification, which is the most basic and important role of the SCR.

In one of the most basic single-phase half-wave controlled rectifier circuit, when the sinusoidal AC voltage is in the positive half-cycle, only in the control pole plus the trigger pulse, the SCR is triggered to conduction, the load will be the voltage output, so you can change the control pole by changing the trigger pulse on the arrival of the time to further regulate the load on the average output voltage, to achieve the role of controlled rectification.

2 Used as a non-contact switch:

The role of the SCR is used as a non-contact switch, often used in automation equipment, instead of general-purpose relays, with no noise, long life.

3 switching and regulating role:

SiC's role is to play the role of switching and regulating the role of the SCR, often used in AC circuits, due to its being triggered by the time is different, so the current through it is only part of the AC cycle, the voltage through it is only a part of the full voltage, and thus play a role in regulating the output voltage.