Specifically what is a thyristor?

A thyristor is actually a high-power semiconductor device, also known as a silicon-controlled rectifier. Its structure contains 4 levels of semiconductor materials, including 3 PN junctions corresponding for the Anode, Cathode, and control electrode Gate. These 3 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 commonly used in various electronic circuits, like controllable rectification, AC voltage regulation, contactless electronic switches, inverters, and frequency alteration.

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 include fast thyristors, bidirectional thyristors, reverse conduction thyristors, and light-weight-controlled thyristors. The working condition in the thyristor is the fact that whenever 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 in between the anode and cathode (the anode is linked to the favorable pole in the power supply, as well as the cathode is attached to the negative pole in the power supply). But no forward voltage is applied for the control pole (i.e., K is disconnected), as well as the indicator light will not glow. 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, along with a forward voltage is applied for the control electrode (known as a trigger, as well as the applied voltage is called trigger voltage), the indicator light switches on. Which means that the transistor can control conduction.

3. Continuous conduction

As shown in Figure c above, right after the thyristor is turned on, whether or not the voltage on the control electrode is removed (that is certainly, K is turned on again), the indicator light still glows. This shows that the thyristor can carry on and conduct. Currently, in order 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 applied for the control electrode, a reverse voltage is applied in between the anode and cathode, as well as the indicator light will not glow currently. This shows that the thyristor will not be conducting and can 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 simply conduct if the gate is exposed to a forward voltage. Currently, the thyristor is in the forward conduction state, the thyristor characteristic, that is certainly, the controllable characteristic.

3) Once the thyristor is turned on, as long as there exists a specific forward anode voltage, the thyristor will always be turned on no matter the gate voltage. That is certainly, right 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 seal to zero, the thyristor turns off.

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

Working principle of thyristor

A thyristor is actually a distinctive triode made from three PN junctions. It may be equivalently viewed as comprising a PNP transistor (BG2) plus an NPN transistor (BG1).

1. If a forward voltage is applied in between the anode and cathode in 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. If a forward voltage is applied 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 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 vital positive feedback, causing both BG1 and BG2 to enter a saturated conduction state quickly. A big current appears inside the emitters of these two transistors, that is certainly, the anode and cathode in the thyristor (the dimensions of the current is actually dependant on the dimensions of the load and the dimensions of Ea), therefore the thyristor is entirely turned on. This conduction process is completed in an exceedingly short time.
2. Following the thyristor is turned on, its conductive state will be maintained by the positive feedback effect in the tube itself. Whether or not the forward voltage in the control electrode disappears, it really is still inside the conductive state. Therefore, the purpose of the control electrode is simply to trigger the thyristor to turn on. After the thyristor is turned on, the control electrode loses its function.
3. The best way to shut off the turned-on thyristor would be to reduce the anode current so that it is insufficient to keep the positive feedback process. The best way to reduce the anode current would be to shut down the forward power supply Ea or reverse the connection of Ea. The minimum anode current needed to maintain the thyristor inside the conducting state is called the holding current in the thyristor. Therefore, as it happens, as long as the anode current is less than the holding current, the thyristor may be switched off.

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

Structure

Transistors usually contain a PNP or NPN structure made from three semiconductor materials.

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

Functioning conditions:

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

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

Application areas

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

Thyristors are mainly utilized in electronic circuits like 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 achieve 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 based on stability and reliability and usually have higher turn-off voltage and larger on-current.

To sum up, although transistors and thyristors can be utilized in similar applications in some cases, because of their different structures and working principles, they have got noticeable differences in performance and use occasions.

Application scope of thyristor

• In power electronic equipment, thyristors can be utilized in frequency converters, motor controllers, welding machines, power supplies, etc.
• In the lighting field, thyristors can be utilized in dimmers and light-weight control devices.
• In induction cookers and electric water heaters, thyristors could 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 an excellent thyristor supplier. It really is one in the leading enterprises in the Home Accessory & Solar Power System, which is fully active in the development of power industry, intelligent operation and maintenance management of power plants, solar power 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. Should you be looking for high-quality thyristor, please feel free to contact us and send an inquiry.