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Presenters:

Jerald Thomas, Steve Jungst

April 25, 2014

Thyristor Structures, Specifications, and Applications

Abstract: Thyristor devices are common, yet largely misunderstood semiconductor devices. In this presentation we go into the background, lithography and structure, basic operations, and finally common applications of the thyristor. At the end we will give our concluding thoughts as well as five key concepts related to the thyristor that we believe all EE students should understand.

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Thyristor origins, background and familySemiconductor structureBasic operationsApplications Questions

Outline

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Thyristor – “thyratron” + “transistor”

Thyristor Origins

Attribution: Eric Barbour

Attribution: Benedikt Seidl

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Proposed by William Shockley in 1950.

Physically created by General Electric in 1956.

Popularized in the 1960’s.

History

Source: Stanford News Service

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Basic Internal Thyristor Structure

Source: Semiconductor Physics and Devices: Basic Principles

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Basic Operations

Attribution: Mikhail RyazanovSource: electrodata.blogspot.com

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1. Reverse Blocking Mode2. Forward Blocking Mode3. Forward Conducting Mode

Three Modes of Operation

Source: Semiconductor Physics and Devices: Basic Principles

Source: Semiconductor Physics and Devices: Basic Principles

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High current and high voltage Controlling AC currentsSnubber circuitsMotor speed controllersLight dimmersPressure-control systems/liquid-level regulators

Applications

Source: www.helvar.nl

Source: www.belimo.pl

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Circuit Application (Crowbar)

Attribution: Steve Jungst

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The thyristor is a unique device, with a unique lithography, capable of many applications. Applications regarding alternating current with lower frequencies are where the thyristor really stands above others.

Summary

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Questions?

Source: Google Patent Search Source: Google Patent Search

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A SCR will continue to conduct current across the anode-cathode junction when the gate potential has been removed as long as the aforementioned current is above the thyristor latching current.

When compared to a transistor, a thyristor has lower switching speeds.

Thyristors main application area is regarding alternating current

A thyristor has three main modes of operation: forward blocking, reverse blocking, and forward conducting.

The thyristor is the successor to the thyratron, a gas filled tube device that could switch large currents using a small control voltage.

Key Concepts:

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Neamen, Donald A. "15.6 | THE THYRISTOR." Semiconductor Physics and Devices: Basic Principles. 4th ed. Vol. 1. New York, NY: McGraw-Hill, 2012. 691-701. Print.

Poole, Ian. "What Is a Thyristor or Silicon Controlled Rectifier, SCR." What Is a Thyristor. Radio-Electronics.com, n.d. Web. 19 Apr. 2014.

"Thyristor Basics." PowerGuru. N.p., 12 Sept. 2012. Web. "Thyristor." Tech-FAQ. Tech-FAQ, 27 Sept. 2012. Web. 20 Apr.

2014. "What Is a Thyristor, SCR?" :: Electronics and Radio Today.

N.p., n.d. Web. 22 Apr. 2014.

Supplemental Reading/Sources