Podcast
Questions and Answers
What is the minimum required semiconductor layers to construct a thyristor?
What is the minimum required semiconductor layers to construct a thyristor?
What is the primary function of a thyristor?
What is the primary function of a thyristor?
What is the term for the value of the anode current at the point where the SUS changes from the forward-blocking region to forward-conducting region?
What is the term for the value of the anode current at the point where the SUS changes from the forward-blocking region to forward-conducting region?
What is the method of firing an SUS?
What is the method of firing an SUS?
Signup and view all the answers
At dv/dt triggering, what happens to junction 2 in a thyristor when it is in the forward-blocking region?
At dv/dt triggering, what happens to junction 2 in a thyristor when it is in the forward-blocking region?
Signup and view all the answers
Study Notes
Thyristors
- Thyristors are constructed using four semiconductor layers (pnpn).
- They include devices such as the 4-layer diode, SCR, diac, triac, SCS, and others.
- Thyristors act as open circuits, capable of withstanding a certain rated voltage until triggered.
- Once triggered, they turn on and become low-resistance current paths, remaining so until the current is reduced to a certain level or until they are triggered off.
Four Layer Diode (Shockley Diode or Silicon Unilateral Switch)
- A type of thyristor constructed from four semiconductor layers.
- SUS Operation:
- Breakover Voltage: minimum forward voltage at which the SUS starts conducting heavily.
- Holding Current: minimum anode current required to maintain the SUS in the on state.
- Switching Current: the value of the anode current at the point where the SUS changes from the forward-blocking region to the forward-conducting region.
Firing an SUS
- Two methods to fire an SUS:
- Supplying a voltage in excess of its breakover voltage.
- Excessive voltage rise in the bias voltage VAK or dv/dt triggering.
- When VAK surpasses the breakover voltage, the SUS saturates and enters the conduction stage.
- The SUS will remain on unless the anode current IA drops below the holding current IH value.
dv/dt Triggering
- At forward-blocking region, the two outer junctions (1 & 3) are forward biased, but the inner junction (2) is reverse biased.
- The reverse-biased junction 2 behaves like a capacitor due to the space-charge present.
- A current will flow in the device to charge the device capacitance.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Learn about the construction and characteristics of thyristors, including their types and functionality. Understand how they work as open circuits and turn on to become low-resistance current paths.
