Specifically what is a thyristor?

A thyristor is actually a high-power semiconductor device, also known as a silicon-controlled rectifier. Its structure consists of 4 levels of semiconductor elements, including three PN junctions corresponding to the Anode, Cathode, and control electrode Gate. These three poles are definitely the critical parts in 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 popular in various electronic circuits, including controllable rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency alteration.

The graphical symbol of a silicon-controlled rectifier is usually represented by the text symbol “V” or “VT” (in older standards, the letters “SCR”). Furthermore, derivatives of thyristors include fast thyristors, bidirectional thyristors, reverse conduction thyristors, and lightweight-controlled thyristors. The working condition in the thyristor is the fact whenever 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 involving the anode and cathode (the anode is connected to the favorable pole in the power supply, and the cathode is linked to the negative pole in the power supply). But no forward voltage is used to the control pole (i.e., K is disconnected), and the indicator light will not light up. This demonstrates that the thyristor is not really 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 used to the control electrode (referred to 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 turned on, even if the voltage on the control electrode is taken off (which is, K is turned on again), the indicator light still glows. This demonstrates that the thyristor can still conduct. At this time, to be able to shut down the conductive thyristor, the power supply Ea has to be shut down or reversed.

4. Reverse blocking

As shown in Figure d above, although a forward voltage is used to the control electrode, a reverse voltage is used involving the anode and cathode, and the indicator light will not light up currently. This demonstrates that the thyristor is not really conducting and can reverse blocking.

5. In conclusion

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

2) When the thyristor is subjected to a forward anode voltage, the thyristor will only conduct when the gate is subjected to a forward voltage. At this time, the thyristor is incorporated in the forward conduction state, which is the thyristor characteristic, which is, the controllable characteristic.

3) When the thyristor is turned on, so long as there exists a specific forward anode voltage, the thyristor will always be turned on whatever the gate voltage. That is certainly, after the thyristor is turned on, the gate will lose its function. The gate only functions as a trigger.

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

5) The disorder for that thyristor to conduct is the fact a forward voltage should be applied involving the anode and the cathode, plus an appropriate forward voltage also need to be applied involving the gate and the cathode. To change off a conducting thyristor, the forward voltage involving the anode and cathode has to be shut down, or the voltage has to be reversed.

Working principle of thyristor

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

1. If a forward voltage is used involving the anode and cathode in the thyristor without applying a forward voltage to the control electrode, although both BG1 and BG2 have forward voltage applied, the thyristor continues to be switched off because BG1 has no base current. If a forward voltage is used to the control electrode currently, BG1 is triggered to produce 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 will likely be brought in the collector of BG2. This current is brought to BG1 for amplification and then brought to BG2 for amplification again. Such repeated amplification forms a crucial 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 in the thyristor (the dimensions of the current is actually dependant on the dimensions of the burden and the dimensions of Ea), so the thyristor is completely turned on. This conduction process is done in a really short time.
2. Right after the thyristor is turned on, its conductive state will likely be maintained by the positive feedback effect in the tube itself. Whether or not the forward voltage in the control electrode disappears, it is still in the conductive state. Therefore, the function of the control electrode is only to trigger the thyristor to turn on. When the thyristor is turned on, the control electrode loses its function.
3. The only method to shut off the turned-on thyristor is always to reduce the anode current that it is insufficient to maintain the positive feedback process. The way to reduce the anode current is always to shut down the forward power supply Ea or reverse the bond of Ea. The minimum anode current necessary to keep your thyristor in the conducting state is referred to as the holding current in the thyristor. Therefore, as it happens, so long as the anode current is under the holding current, the thyristor can be switched off.

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

Structure

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

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

Working conditions:

The work of a 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 turn on or off.

Application areas

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

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

Means of working

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

The thyristor is turned on or off by managing the trigger voltage in the control electrode to realize the switching function.

Circuit parameters

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

To sum up, although transistors and thyristors can be used in similar applications sometimes, because of their different structures and working principles, they may have noticeable variations in performance and utilize occasions.

Application scope of thyristor

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

Supplier

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

It accepts payment via Credit 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 looking for high-quality thyristor, please feel free to contact us and send an inquiry.