Specifically what is a thyristor?

A thyristor is actually a high-power semiconductor device, also referred to as a silicon-controlled rectifier. Its structure includes 4 quantities of semiconductor elements, including three PN junctions corresponding towards the Anode, Cathode, and control electrode Gate. These three poles are the critical parts from 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 functioning status. Therefore, thyristors are popular in different electronic circuits, including controllable rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency conversion.

The graphical symbol of a semiconductor device is normally represented by the text symbol “V” or “VT” (in older standards, the letters “SCR”). In addition, derivatives of thyristors also have fast thyristors, bidirectional thyristors, reverse conduction thyristors, and lightweight-controlled thyristors. The functioning condition from the thyristor is that when a forward voltage is applied, 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 from the power supply, and the cathode is linked to the negative pole from the power supply). But no forward voltage is applied towards the control pole (i.e., K is disconnected), and the indicator light does not light up. This shows that the thyristor will not be conducting and has forward blocking capability.

2. Controllable conduction

As shown in Figure b above, when K is closed, as well as a forward voltage is applied towards the control electrode (referred to as a trigger, and 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 turned on, whether or not the voltage in the control electrode is taken off (which is, K is turned on again), the indicator light still glows. This shows that the thyristor can carry on and conduct. At this time, so that you can stop the conductive thyristor, the power supply Ea should be stop 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 the indicator light does not light up at the moment. This shows that the thyristor will not be conducting and will reverse blocking.

5. In summary

1) When the thyristor is put through a reverse anode voltage, the thyristor is at a reverse blocking state whatever voltage the gate is put through.

2) When the thyristor is put through a forward anode voltage, the thyristor will simply conduct if the gate is put through a forward voltage. At this time, the thyristor is in the forward conduction state, the thyristor characteristic, which is, the controllable characteristic.

3) When the thyristor is turned on, so long as you will find a specific forward anode voltage, the thyristor will remain turned on whatever the gate voltage. Which is, following the thyristor is turned on, the gate will lose its function. The gate only serves as a trigger.

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

5) The problem for the thyristor to conduct is that a forward voltage ought to 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 transform off a conducting thyristor, the forward voltage involving the anode and cathode should be stop, or perhaps the voltage should be reversed.

Working principle of thyristor

A thyristor is essentially a unique triode composed of three PN junctions. It can be equivalently regarded as consisting of a PNP transistor (BG2) plus an NPN transistor (BG1).

1. If a forward voltage is applied involving the anode and cathode from the thyristor without applying a forward voltage towards the control electrode, although both BG1 and BG2 have forward voltage applied, the thyristor remains turned off because BG1 has no base current. If a forward voltage is applied towards the control electrode at the moment, BG1 is triggered to generate basics current Ig. BG1 amplifies this current, as well as 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 brought in the collector of BG2. This current is delivered to BG1 for amplification and then delivered 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 these two transistors, which is, the anode and cathode from the thyristor (the size of the current is in fact dependant on the size of the burden and the size of Ea), therefore the thyristor is entirely turned on. This conduction process is finished in a really short period of time.
2. After the thyristor is turned on, its conductive state will likely be maintained by the positive feedback effect from the tube itself. Even when the forward voltage from the control electrode disappears, it is actually still in the conductive state. Therefore, the function of the control electrode is only to trigger the thyristor to turn on. After the thyristor is turned on, the control electrode loses its function.
3. The best way to turn off the turned-on thyristor is to lessen the anode current that it is not enough to maintain the positive feedback process. How you can lessen the anode current is to stop the forward power supply Ea or reverse the link of Ea. The minimum anode current necessary to keep your thyristor in the conducting state is referred to as the holding current from the thyristor. Therefore, as it happens, so long as the anode current is less than the holding current, the thyristor could be turned off.

What is the distinction between a transistor as well as 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 task 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 turn on or off.

Application areas

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

Thyristors are mainly 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 accomplish current amplification.

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

Circuit parameters

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

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

Application scope of thyristor

• In power electronic equipment, thyristors can be used in frequency converters, motor controllers, welding machines, power supplies, etc.
• Inside the lighting field, thyristors can 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 can be used in motor controllers.

Supplier

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