Specifically what is a thyristor?

A thyristor is actually a high-power semiconductor device, also called a silicon-controlled rectifier. Its structure consists of 4 quantities of semiconductor components, including three PN junctions corresponding towards the Anode, Cathode, and control electrode Gate. These three poles are the critical parts of the thyristor, letting it control current and perform high-frequency switching operations. Thyristors can operate under high voltage and high current conditions, and external signals can maintain their functioning status. Therefore, thyristors are popular in different electronic circuits, such as controllable rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency conversion.

The graphical symbol of a Thyristor is generally represented by the text symbol “V” or “VT” (in older standards, the letters “SCR”). In addition, derivatives of thyristors also include fast thyristors, bidirectional thyristors, reverse conduction thyristors, and light-weight-controlled thyristors. The functioning condition of the thyristor is the fact that each time a forward voltage is used, the gate needs to have a trigger current.

Characteristics of thyristor

1. Forward blocking

As shown in Figure a above, when an ahead voltage is utilized between the anode and cathode (the anode is linked to the favorable pole of the power supply, and the cathode is connected to the negative pole of the power supply). But no forward voltage is used towards the control pole (i.e., K is disconnected), and the indicator light does not glow. This demonstrates that the thyristor will not be conducting and contains forward blocking capability.

2. Controllable conduction

As shown in Figure b above, when K is closed, as well as a forward voltage is used towards the control electrode (known as a trigger, and the applied voltage is referred to as trigger voltage), the indicator light switches on. Because of this the transistor can control conduction.

3. Continuous conduction

As shown in Figure c above, after the thyristor is excited, even when the voltage on the control electrode is taken off (that is certainly, K is excited again), the indicator light still glows. This demonstrates that the thyristor can carry on and conduct. At the moment, so that you can cut off the conductive thyristor, the power supply Ea should be cut off or reversed.

4. Reverse blocking

As shown in Figure d above, although a forward voltage is used towards the control electrode, a reverse voltage is used between the anode and cathode, and the indicator light does not glow at this time. This demonstrates that the thyristor will not be conducting and can reverse blocking.

5. To sum up

1) Once the thyristor is subjected to a reverse anode voltage, the thyristor is within a reverse blocking state no matter what voltage the gate is subjected to.

2) Once the thyristor is subjected to a forward anode voltage, the thyristor is only going to conduct once the gate is subjected to a forward voltage. At the moment, the thyristor is within the forward conduction state, which is the thyristor characteristic, that is certainly, the controllable characteristic.

3) Once the thyristor is excited, provided that you will find a specific forward anode voltage, the thyristor will always be excited regardless of the gate voltage. That is certainly, after the thyristor is excited, the gate will lose its function. The gate only functions as a trigger.

4) Once the thyristor is on, and the primary circuit voltage (or current) decreases to close to zero, the thyristor turns off.

5) The condition for that thyristor to conduct is the fact that a forward voltage should be applied between the anode and the cathode, as well as an appropriate forward voltage also need to be applied between the gate and the cathode. To change off a conducting thyristor, the forward voltage between the anode and cathode should be cut off, or even the voltage should be reversed.

Working principle of thyristor

A thyristor is actually a unique triode made up of three PN junctions. It may be equivalently viewed as consisting of a PNP transistor (BG2) as well as an NPN transistor (BG1).

1. When a forward voltage is used between the anode and cathode of the thyristor without applying a forward voltage towards the control electrode, although both BG1 and BG2 have forward voltage applied, the thyristor remains switched off because BG1 has no base current. When a forward voltage is used towards the control electrode at this time, BG1 is triggered to produce a base current Ig. BG1 amplifies this current, as well as a ß1Ig current is obtained in its collector. This current is precisely the base current of BG2. After amplification by BG2, a ß1ß2Ig current will be brought in the collector of BG2. This current is brought to BG1 for amplification then brought to BG2 for amplification again. Such repeated amplification forms a vital positive feedback, causing both BG1 and BG2 to get in a saturated conduction state quickly. A big current appears inside the emitters of these two transistors, that is certainly, the anode and cathode of the thyristor (the dimensions of the current is in fact based on the dimensions of the stress and the dimensions of Ea), so the thyristor is completely excited. This conduction process is completed in an exceedingly limited time.
2. After the thyristor is excited, its conductive state will be maintained by the positive feedback effect of the tube itself. Even when the forward voltage of the control electrode disappears, it is still inside the conductive state. Therefore, the purpose of the control electrode is only to trigger the thyristor to transform on. When the thyristor is excited, the control electrode loses its function.
3. The best way to shut off the turned-on thyristor would be to decrease the anode current that it is inadequate to keep up the positive feedback process. How you can decrease the anode current would be to cut off the forward power supply Ea or reverse the connection of Ea. The minimum anode current required to keep the thyristor inside the conducting state is referred to as the holding current of the thyristor. Therefore, as it happens, provided that the anode current is less than the holding current, the thyristor may be switched off.

What exactly is the distinction between a transistor as well as a thyristor?

Structure

Transistors usually include a PNP or NPN structure made up of three semiconductor materials.

The thyristor consists of four PNPN structures of semiconductor materials, including anode, cathode, and control electrode.

Functioning conditions:

The work of a transistor relies upon electrical signals to control its closing and opening, allowing fast switching operations.

The thyristor requires a forward voltage as well as a trigger current on the gate to transform on or off.

Application areas

Transistors are popular in amplification, switches, oscillators, and other facets of electronic circuits.

Thyristors are mostly utilized in electronic circuits such as controlled rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency conversions.

Way of working

The transistor controls the collector current by holding the base current to accomplish current amplification.

The thyristor is excited or off by manipulating the trigger voltage of the control electrode to understand the switching function.

Circuit parameters

The circuit parameters of thyristors are related to stability and reliability and usually have higher turn-off voltage and larger on-current.

To sum up, although transistors and thyristors may be used in similar applications in some instances, due to their different structures and functioning principles, they have noticeable variations in performance and make use of occasions.

Application scope of thyristor

• In power electronic equipment, thyristors may be used in frequency converters, motor controllers, welding machines, power supplies, etc.
• Inside the lighting field, thyristors may be used in dimmers and light-weight control devices.
• In induction cookers and electric water heaters, thyristors can be used to control the current flow towards the heating element.
• In electric vehicles, transistors may be used in motor controllers.

Supplier

PDDN Photoelectron Technology Co., Ltd is a wonderful thyristor supplier. It is actually one of the leading enterprises in the Home Accessory & Solar Power System, which can be fully involved in the progression of power industry, intelligent operation and maintenance management of power plants, solar power and related solar products manufacturing.

It accepts payment via Charge Card, T/T, West Union and Paypal. PDDN will ship the goods to customers overseas through FedEx, DHL, by air, or by sea. If you are searching for high-quality thyristor, please feel free to contact us and send an inquiry.