Specifically what is a thyristor?

A thyristor is a high-power semiconductor device, also referred to as a silicon-controlled rectifier. Its structure consists of four quantities of semiconductor components, including 3 PN junctions corresponding towards the Anode, Cathode, and control electrode Gate. These 3 poles are 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 working status. Therefore, thyristors are commonly used in different electronic circuits, including controllable rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency alteration.

The graphical symbol of any semiconductor device is generally represented from the text symbol “V” or “VT” (in older standards, the letters “SCR”). Additionally, derivatives of thyristors also include fast thyristors, bidirectional thyristors, reverse conduction thyristors, and lightweight-controlled thyristors. The working condition of the thyristor is that each time 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 utilized involving the anode and cathode (the anode is linked to the favorable pole of the power supply, and also the cathode is connected to the negative pole of the power supply). But no forward voltage is applied towards the control pole (i.e., K is disconnected), and also the indicator light does not glow. This demonstrates that the thyristor is not conducting and contains forward blocking capability.

2. Controllable conduction

As shown in Figure b above, when K is closed, along with a forward voltage is applied towards the control electrode (called a trigger, and also the applied voltage is called trigger voltage), the indicator light turns 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 around the control electrode is taken away (that is certainly, K is excited again), the indicator light still glows. This demonstrates that the thyristor can carry on and conduct. Currently, in order to shut down the conductive thyristor, the power supply Ea must be shut down or reversed.

4. Reverse blocking

As shown in Figure d above, although a forward voltage is applied towards the control electrode, a reverse voltage is applied involving the anode and cathode, and also the indicator light does not glow at this time. This demonstrates that the thyristor is not conducting and may reverse blocking.

5. To sum up

1) Once the thyristor is exposed to a reverse anode voltage, the thyristor is within a reverse blocking state whatever voltage the gate is exposed to.

2) Once the thyristor is exposed to a forward anode voltage, the thyristor will only conduct once the gate is exposed to a forward voltage. Currently, the thyristor is incorporated in the forward conduction state, which is the thyristor characteristic, that is certainly, the controllable characteristic.

3) Once the thyristor is excited, as long as there is a specific forward anode voltage, the thyristor will stay excited regardless of the gate voltage. That is certainly, following the thyristor is excited, the gate will lose its function. The gate only works as a trigger.

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

5) The problem for your thyristor to conduct is that a forward voltage needs to be applied involving the anode and also the cathode, and an appropriate forward voltage ought to be applied involving the gate and also the cathode. To change off a conducting thyristor, the forward voltage involving the anode and cathode must be shut down, or perhaps the voltage must be reversed.

Working principle of thyristor

A thyristor is basically a unique triode composed of three PN junctions. It may be equivalently viewed as comprising a PNP transistor (BG2) and an NPN transistor (BG1).

1. In case a forward voltage is applied involving 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 is still turned off because BG1 has no base current. In case a forward voltage is applied towards the control electrode at this time, BG1 is triggered to produce a base current Ig. BG1 amplifies this current, along with a ß1Ig current is obtained in the collector. This current is precisely the base current of BG2. After amplification by BG2, a ß1ß2Ig current will likely be introduced the collector of BG2. This current is delivered to BG1 for amplification and after that delivered to BG2 for amplification again. Such repeated amplification forms a vital positive feedback, causing both BG1 and BG2 to get into 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 (how big the current is really based on how big the stress and how big Ea), and so the thyristor is totally excited. This conduction process is finished in an exceedingly short period of time.
2. After the thyristor is excited, its conductive state will likely be maintained from 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 function 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 best way to switch off the turned-on thyristor is to reduce the anode current that it is not enough to maintain the positive feedback process. The way to reduce the anode current is to shut down the forward power supply Ea or reverse the link of Ea. The minimum anode current necessary to keep your thyristor inside the conducting state is called the holding current of the thyristor. Therefore, strictly speaking, as long as the anode current is less than the holding current, the thyristor may be turned off.

What exactly 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.

Working conditions:

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

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

Application areas

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

Thyristors are mostly found in electronic circuits including controlled rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency conversions.

Method 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 based on stability and reliability and in most cases 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, because of the different structures and working 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 lightweight 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 an excellent thyristor supplier. It really is one of the leading enterprises in the Home Accessory & Solar Power System, which can be fully working in the progression of power industry, intelligent operation and maintenance handling of power plants, solar power panel and related solar products manufacturing.

It accepts payment via Bank 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.