Specifically what is a thyristor?

A thyristor is a high-power semiconductor device, also called a silicon-controlled rectifier. Its structure includes 4 quantities of semiconductor components, including three PN junctions corresponding for the Anode, Cathode, and control electrode Gate. These three poles are definitely 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 operating status. Therefore, thyristors are commonly used in different electronic circuits, like controllable rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency alteration.

The graphical symbol of the Thyristor is normally represented through the text symbol “V” or “VT” (in older standards, the letters “SCR”). Additionally, derivatives of thyristors also have fast thyristors, bidirectional thyristors, reverse conduction thyristors, and light-weight-controlled thyristors. The operating condition from the thyristor is that whenever a forward voltage is used, 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 from the power supply, as well as the cathode is connected to the negative pole from the power supply). But no forward voltage is used for the control pole (i.e., K is disconnected), as well as the indicator light fails to light up. This shows 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 used for the control electrode (referred to 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, after the thyristor is turned on, even when the voltage on the control electrode is taken away (that is certainly, K is turned on again), the indicator light still glows. This shows that the thyristor can carry on and conduct. Currently, to be able to shut down the conductive thyristor, the power supply Ea should be shut down or reversed.

4. Reverse blocking

As shown in Figure d above, although a forward voltage is used for the control electrode, a reverse voltage is used involving the anode and cathode, as well as the indicator light fails to light up currently. This shows that the thyristor is not conducting and may reverse blocking.

5. In summary

1) Once the thyristor is put through a reverse anode voltage, the thyristor is within a reverse blocking state regardless of what voltage the gate is put through.

2) Once the thyristor is put through a forward anode voltage, the thyristor will only conduct if the gate is put through 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 turned on, as long as you will find a specific forward anode voltage, the thyristor will remain turned on whatever the gate voltage. That is, after the thyristor is turned on, the gate will lose its function. The gate only functions as a trigger.

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

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

Working principle of thyristor

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

1. In case a forward voltage is used involving the anode and cathode from the thyristor without applying a forward voltage for the control electrode, although both BG1 and BG2 have forward voltage applied, the thyristor is still switched off because BG1 has no base current. In case a forward voltage is used for the control electrode currently, BG1 is triggered to produce basics 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 then delivered to BG2 for amplification again. Such repeated amplification forms a crucial positive feedback, causing both BG1 and BG2 to enter a saturated conduction state quickly. A big current appears within the emitters of the two transistors, that is certainly, the anode and cathode from the thyristor (how big the current is actually determined by how big the load and how big Ea), so the thyristor is completely turned on. This conduction process is done in a really short time.
2. After the thyristor is turned on, its conductive state will likely be maintained through the positive feedback effect from the tube itself. Even if the forward voltage from the control electrode disappears, it really is still within the conductive state. Therefore, the function of the control electrode is simply to trigger the thyristor to turn on. When the thyristor is turned on, the control electrode loses its function.
3. The best way to shut off the turned-on thyristor is to lessen the anode current so that it is insufficient to maintain the positive feedback process. The best way to lessen the anode current is to shut down the forward power supply Ea or reverse the link of Ea. The minimum anode current needed to maintain the thyristor within the conducting state is referred to as the holding current from the thyristor. Therefore, as it happens, as long as the anode current is lower than the holding current, the thyristor could be switched 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 consists of four PNPN structures of semiconductor materials, including anode, cathode, and control electrode.

Functioning conditions:

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

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

Application areas

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

Thyristors are mostly found in electronic circuits like 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 attain current amplification.

The thyristor is turned on or off by managing the trigger voltage from the control electrode to understand 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 summarize, although transistors and thyristors may be used in similar applications sometimes, due to their different structures and operating principles, they have noticeable differences in performance and utilize 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 may be used to control the current flow for the heating element.
• In electric vehicles, transistors may be used in motor controllers.

Supplier

PDDN Photoelectron Technology Co., Ltd is a superb thyristor supplier. It really is one from the leading enterprises in the Home Accessory & Solar Power System, which can be fully active in the 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.