What is a Thyristor and how does it work?

A complete guide about thyristor:

The thyristor is a power semiconductor that is used as a switch, either to conduct or interrupt the electric current, this component is known as power because they are used to handle large amounts of current and voltage, compared to the others semiconductors that handle relatively low quantities. When talking about thyristors, the thyristor is commonly cataloged as an SRC (silicon controlled rectifier), but this is not quite correct since this type is the most popular and well known but it is not the only one that exists.

How does a thyristor work?

The thyristors are made up of 3 terminals an anode, a cathode and a gate or better known "gate", its operation resembles that of a relay or a mechanical switch, since when you apply a current to the gate terminal it activates and obtains the characteristic of letting electricity pass.

Types of thyristor

There is a great variety of thyristors, each one has different properties, characteristics, advantages, and disadvantages.

Phase control or rapid communication (SCR): This type is the most common and most used because they can switch quickly. One of the main characteristics of this thyristor is that it is only able to conduct electricity to only one direction (such as a diode when it is polarized directly), once this component is activated it does not matter if you remove the current from the door since it will remain active until that one of two possible conditions is met. To deactivate it you have to cut off the power supply or take it to a very low point that the thyristor is unable to continue driving.

Bidirectional controlled by face (BCT): This type corresponds to two thyristors in the same package, although they are together they do not interfere with each other having its door terminals to be activated.

Bidirectional Triode (TRIAC): It is used for alternating current since it contains two thyristors together in the same package, this time they only have one door terminal and this is capable of activating the two components at the same time.

Reverse Driving (RCT): It could be said that it is an SCR with the integration of a diode placed in parallel but inversely, this is used to prevent parasitic currents generated due to inductions circulating against current flow.

Gate deactivation (GTO): This type is an improvement of the SCR thyristor since it can be deactivated through your door with the only condition of applying negative voltage.

Controlled by FET-CTH: This type incorporates a thyristor and a Mosfet transistor in parallel, which is responsible for generating the tripping current for the thyristor. This device is like conventional devices can be activated but not deactivated unless the circuit current is removed or the current is very low.

Switched by an integrated gate (IGCT):

This is the evolution of the GTO, its activation is through its door terminal, to deactivate it the same terminal is used only that this component incorporates a control stage to be able to apply very high and very fast negative voltage.

AuthorNeptune India