What are the characteristics of thyristor?
A Thyristor is a unidirectional semiconductor solid state device with four layers of alternating P and N type material. It consist of three electrodes i.e. Anode, Cathode and a Gate. Anode is the positive terminal and Cathode is the negative terminal. The Gate controls the flow of current between anode and cathode.
What are the switching characteristics of SCR?
Switching characteristics of SCR is the time variation of voltage across its anode and cathode terminals and the current through it during its turn on and turn off process. This means, there will be two types of characteristics: One during turn on process and other during turn off process of SCR.
What are the switching characteristics?
The switching characteristics are important particularly at high-frequency, to define the device velocity in changing from conduction state to blocking state and vice versa. Losses occurring in the device during switching from ON state to OFF state and OFF state to ON state is known as Switching Losses.
How thyristor works as a switch?
When connected to a direct current DC supply, the thyristor can be used as a DC switch to control larger DC currents and loads. When using the Thyristor as a switch it behaves like an electronic latch because once activated it remains in the “ON” state until manually reset.
What is VI characteristics of PN junction diode?
VI characteristics of P-N junction diodes is a curve between the voltage and current through the circuit. Voltage is taken along the x-axis while the current is taken along the y-axis. The above graph is the V-I characteristics curve of the P-N junction diode.
What is the turn off characteristic of thyristors?
Turn off Switching Characteristics The turn off time tq of a thyristor is defined as the time between the instant anodes current becomes zero and the instant the thyristor regains forward blocking capability. During turn off time, excess minority carriers from all the four layers of the thyristor must be removed.
What is reverse recovery characteristics of thyristor?
The thyristor belongs to the bipolar devices, and there are many excess carriers in the thyristor’s base region during the thyristor’s ON time. The excess carriers (i.e. reverse recovery charge) must be cleared during the turn-off process, then the device can recover its’ ability for withstanding input voltage.
What is switching characteristics of BJT?
If we neglect the reverse-current components, since the collector-base diode is also reverse-biased, the BJT is cut-off and no current exists anywhere in the circuit. Consequently, vo = VCC, and with iC = 0, this is an open switch.
What is difference between diode and thyristor?
Thyristor has three terminal known as anode, cathode, and gate while diode has two terminal known as anode and cathode. Thyristor works only in one direction while the diode can work in both directions. Power handling capacity is better for SCRs than comparing to other diodes.
What is thyristor and its function?
Thyristors are mainly used where high currents and voltages are involved, and are often used to control alternating currents, where the change of polarity of the current causes the device to switch off automatically, referred to as “zero cross” operation.
What is IV characteristics of pn junction diode?
I-V Characteristic Curve of a Diode When the forward voltage exceeds the diodes P-N junctions internal barrier voltage, which for silicon is about 0.7 volts, avalanche occurs and the forward current increases rapidly for a very small increase in voltage producing a non-linear curve.
What is pn junction diode and its characteristics?
A PN Junction Diode is one of the simplest semiconductor devices around, and which has the electrical characteristic of passing current through itself in one direction only. However, unlike a resistor, a diode does not behave linearly with respect to the applied voltage.
What are the turn on and turn-off methods of thyristor?
There are three methods of switching off the SCR, namely natural commutation, reverse bias turn-off, and gate turn-off.
What is diode reverse recovery characteristics?
Reverse Recovery Characteristics of Power Diodes This time is defined as reverse recovery time and is defined as the time between the instant forward current reaches zero and the instant the reverse current decays to 25% of IRR. After this time the diode is said to attain its reverse blocking capability.
What are the different types of thyristor?
Types of Thyristors
- Phase Controlled Thyristors.
- Asymmetrical Thyristors (ASCRs)
- Inverter-grade Thyristors (fast switching speed SCRs)
- Reverse Conducting Thyristors (RCTs)
- Bidirectional Diode Thyristors (DIACs)
- Gate Assisted Turn-off Thyristors (GATT)
- Bidirectional Triode Thyristors (TRIACs)
- Silicon Control Switch (SCS)
Why BJT is used as switch?
The transistor can be used as a switch if biased in the saturation and cut-off regions. This allows current to flow (or not) in other parts of a circuit. Because a transistor’s collector current is proportionally limited by its base current, it can be used as a sort of current-controlled switch.
What are the characteristics of PN junction region of junction diode?
The PN junction region of a Junction Diode has the following important characteristics: Semiconductors contain two types of mobile charge carriers, “Holes” and “Electrons”. The holes are positively charged while the electrons negatively charged.
What is reverse bias pn junction diode?
Reverse Biased PN Junction Diode. When a diode is connected in a Reverse Bias condition, a positive voltage is applied to the N-type material and a negative voltage is applied to the P-type material.
What is rectification in PN junction diodes?
One of the results produces rectification as seen in the PN junction diodes static I-V (current-voltage) characteristics. Rectification is shown by an asymmetrical current flow when the polarity of bias voltage is altered as shown below.
What are switching characteristics of a thyristor?
We know that in general terms, that a switch is used to connect or disconnect an electrical circuit and the connection and disconnection cause the device to get turned on or off. In a similar way, when the switching characteristics of the thyristor are discussed then it is considered in reference to the turn on and turn off behavior of the device.