Specifically what is a thyristor?

A thyristor is really a high-power semiconductor device, also known as a silicon-controlled rectifier. Its structure includes 4 levels of semiconductor elements, including three PN junctions corresponding for the Anode, Cathode, and control electrode Gate. These three poles are definitely the critical parts of the thyristor, allowing it to control current and perform high-frequency switching operations. Thyristors can operate under high voltage and high current conditions, and external signals can maintain their operating status. Therefore, thyristors are popular in various electronic circuits, like controllable rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency alteration.

The graphical symbol of any Thyristor is normally represented from 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 operating condition of the thyristor is the fact when a forward voltage is applied, the gate will need to have a trigger current.

Characteristics of thyristor

1. Forward blocking

As shown in Figure a above, when an ahead voltage is used involving the anode and cathode (the anode is linked to the favorable pole of the power supply, as well as the cathode is attached to the negative pole of the power supply). But no forward voltage is applied for the control pole (i.e., K is disconnected), as well as the indicator light does not glow. This implies that the thyristor is not conducting and has forward blocking capability.

2. Controllable conduction

As shown in Figure b above, when K is closed, along with a forward voltage is applied for the control electrode (known as a trigger, as well as the applied voltage is referred to as trigger voltage), the indicator light switches on. Which means that the transistor can control conduction.

3. Continuous conduction

As shown in Figure c above, following the thyristor is excited, even when the voltage in the control electrode is taken away (which is, K is excited again), the indicator light still glows. This implies that the thyristor can continue to conduct. Currently, to be able to stop the conductive thyristor, the power supply Ea must be stop or reversed.

4. Reverse blocking

As shown in Figure d above, although a forward voltage is applied for the control electrode, a reverse voltage is applied involving the anode and cathode, as well as the indicator light does not glow currently. This implies that the thyristor is not conducting and will reverse blocking.

5. To sum up

1) When the thyristor is exposed to a reverse anode voltage, the thyristor is at a reverse blocking state regardless of what voltage the gate is exposed to.

2) When the thyristor is exposed to a forward anode voltage, the thyristor will only conduct if the gate is exposed to a forward voltage. Currently, the thyristor is in the forward conduction state, which is the thyristor characteristic, which is, the controllable characteristic.

3) When the thyristor is excited, so long as there is a specific forward anode voltage, the thyristor will stay excited no matter the gate voltage. Which is, following the thyristor is excited, the gate will lose its function. The gate only serves as a trigger.

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

5) The problem for your thyristor to conduct is the fact a forward voltage ought to be applied involving the anode as well as the cathode, and an appropriate forward voltage ought to be applied involving the gate as well as the cathode. To transform off a conducting thyristor, the forward voltage involving the anode and cathode must be stop, or the voltage must be reversed.

Working principle of thyristor

A thyristor is basically a distinctive triode composed of three PN junctions. It can be equivalently thought to be composed of a PNP transistor (BG2) and an NPN transistor (BG1).

1. If a forward voltage is applied involving the anode and cathode of the thyristor without applying a forward voltage for the control electrode, although both BG1 and BG2 have forward voltage applied, the thyristor is still turned off because BG1 has no base current. If a forward voltage is applied for the control electrode currently, BG1 is triggered to create basics current Ig. BG1 amplifies this current, along with a ß1Ig current is obtained in their collector. This current is precisely the base current of BG2. After amplification by BG2, a ß1ß2Ig current is going to be brought in the collector of BG2. This current is sent to BG1 for amplification and after that sent to BG2 for amplification again. Such repeated amplification forms an essential positive feedback, causing both BG1 and BG2 to get in a saturated conduction state quickly. A sizable current appears in the emitters of the two transistors, which is, the anode and cathode of the thyristor (the size of the current is actually determined by the size of the stress and the size of Ea), therefore the thyristor is completely excited. This conduction process is completed in a really short time.
2. Right after the thyristor is excited, its conductive state is going to be maintained from the positive feedback effect of the tube itself. Even if the forward voltage of the control electrode disappears, it is actually still in the conductive state. Therefore, the purpose of the control electrode is simply to trigger the thyristor to change on. Once the thyristor is excited, the control electrode loses its function.
3. The only way to turn off the turned-on thyristor would be to reduce the anode current so that it is not enough to maintain the positive feedback process. How you can reduce the anode current would be to stop the forward power supply Ea or reverse the connection of Ea. The minimum anode current required to keep the thyristor in the conducting state is referred to as the holding current of the thyristor. Therefore, strictly speaking, so long as the anode current is lower than the holding current, the thyristor could be turned off.

Exactly what is the difference between a transistor along with a thyristor?

Structure

Transistors usually contain a PNP or NPN structure composed of three semiconductor materials.

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

Operating conditions:

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

The thyristor needs a forward voltage along with a trigger current at the gate to change on or off.

Application areas

Transistors are popular in amplification, switches, oscillators, along with other aspects of electronic circuits.

Thyristors are mostly utilized in electronic circuits like 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 achieve current amplification.

The thyristor is excited or off by manipulating the trigger voltage of the control electrode to realize 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 summarize, although transistors and thyristors can be utilized in similar applications sometimes, because of the different structures and operating principles, they have got noticeable variations in performance and make use of occasions.

Application scope of thyristor

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

Supplier

PDDN Photoelectron Technology Co., Ltd is a superb thyristor supplier. It is actually one of the leading enterprises in the Home Accessory & Solar Power System, that is fully working in the progression of power industry, intelligent operation and maintenance handling of power plants, solar panel 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. Should you be looking for high-quality thyristor, please feel free to contact us and send an inquiry.