What is a Thyristor?
A thyristor is a semiconductor device that works as a switch in electronic circuits. It is a four-layered device with three p-type and one n-type silicon layer. The layers are alternately stacked and connected through a metal electrode. The two p-type layers are connected through a region called the p-n-p-n structure.
- The thyristors are used extensively in power electronic circuits. They are operated as bistable switches, operating from of state to conducting state.
- A thyristor is a four-layer semiconductor device, consisting of alternating P-type and N-type materials (PNPN). A thyristor usually has three electrodes: an anode, a cathode and a gate, also known as a control electrode.
- Thyristor symbol representation is shown below:
The member of the Thyristors family are SCR, LASCR, RCT, GTO, SITH, and MCT. Thyristors are a class of semiconductor devices characterized by 4-layers of alternating p and n material. Four-layer devices act as either open or closed switches; for this reason, they are most frequently used in control applications.
The thyristor is a unidirectional device, which means it can only conduct current in one direction. It has three terminals, an anode, a cathode and a gate. The anode is the positive terminal, the cathode is the negative terminal, and the gate is used to control the flow of current from the anode to the cathode. When a small voltage is applied to the gate, the thyristor turns on, allowing a large current to flow through it.
The most common type of thyristor is the silicon-controlled rectifier (SCR). When the cathode is negatively charged relative to the anode, no current flows until a pulse is applied to the gate. Then, the SCR conducts current until the voltage between the cathode and anode is reversed or reduced below a certain threshold or holding value. Using this type of thyristor, large amounts of power can be switched or controlled using a small triggering current or voltage.
What is Thyristors in Power Electronics ?
Thyristors in Power Electronics are used as power semiconductor devices which are used as on/off switches in power control circuits. A power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics for example in a switch-mode power supply. A thyristor is the most important type of power semiconductor device. They are extensively used in power electronic circuits. They are operated as bi-stable switches from non-conducting to conducting state. Thyristors are high speed switches that can be used to replace electromechanical relays in many circuits as they have no moving parts, no contact arcing, or suffer from corrosion or dirt. But in addition to simply switching large currents “ON” and “OFF”, thyristors can be made to control the mean value of an AC load current without dissipating large amounts of power.
Table of Content
- What is a Thyristor?
- Properties of Thyristors
- Construction of Thyristor
- Working of Thyristor
- V-I characteristics of thyristor
- Types of Thyristors in Power Electronics
- Examples of Thyristors in Power Electronics