Information about Magnetic Amplifier
The magnetic amplifier (colloquially known as the "mag amp") is an electromagnetic device for amplifying electrical signals. The magnetic amplifier was invented early in the 20th century, and was used as an alternative to vacuum tube amplifiers where robustness and high current capacity were required. World War II Germany perfected this type of amplifier, and it was used for instance in the V-2 rocket. The magnetic amplifier has now been largely superseded by the transistor-based amplifier, except in a few safety critical, high reliability or extremely demanding applications.
Visually a mag amp device may resemble a transformer but the operating principle is quite different from a transformer - essentially the mag amp is a saturable reactor. It makes use of magnetic saturation of the core, a non-linear property of a certain class of transformer cores. For controlled saturation characteristics the magnetic amplifier employs core materials that have been designed to have a specific B-H curve shape that is highly rectangular, in contrast to the slowly tapering B-H curve of softly saturating core materials that are often used in normal transformers.
The typical magnetic amplifier consists of two physically separate but similar transformer magnetic cores, each of which has two windings - a control winding and an AC winding. A small DC current from a low impedance source is fed into the series-connected control windings. An AC voltage is fed into one AC winding, with the other AC winding connected to the load. The AC windings may be connected either in series or in parallel, the configurations resulting in different types of mag amps. The amount of control current fed into the control winding sets the point in the AC winding waveform at which either core will saturate. In saturation, the AC winding on the saturated core will go from a high impedance state ("off") into a very low impedance state ("on") - that is, the control current controls at which voltage the mag amp switches "on".
A relatively small DC current on the control winding is able to control or switch large AC currents on the AC windings. This results in current amplification.
Mag amp diagram
Magnetic amplifier transformer cores designed specifically for switch mode power supplies are currently manufactured by several large electromagnetics companies, including Metglas and Mag-Inc.
Magnetic amplifiers can be used for measuring high DC-voltages without direct connection to the high voltage and are therefore still used in the HVDC-technique.
Principle of operation
The mag amp is a "magnetic field" kind of amplifier and is of Class H type.Visually a mag amp device may resemble a transformer but the operating principle is quite different from a transformer - essentially the mag amp is a saturable reactor. It makes use of magnetic saturation of the core, a non-linear property of a certain class of transformer cores. For controlled saturation characteristics the magnetic amplifier employs core materials that have been designed to have a specific B-H curve shape that is highly rectangular, in contrast to the slowly tapering B-H curve of softly saturating core materials that are often used in normal transformers.
The typical magnetic amplifier consists of two physically separate but similar transformer magnetic cores, each of which has two windings - a control winding and an AC winding. A small DC current from a low impedance source is fed into the series-connected control windings. An AC voltage is fed into one AC winding, with the other AC winding connected to the load. The AC windings may be connected either in series or in parallel, the configurations resulting in different types of mag amps. The amount of control current fed into the control winding sets the point in the AC winding waveform at which either core will saturate. In saturation, the AC winding on the saturated core will go from a high impedance state ("off") into a very low impedance state ("on") - that is, the control current controls at which voltage the mag amp switches "on".
A relatively small DC current on the control winding is able to control or switch large AC currents on the AC windings. This results in current amplification.
Mag amp diagram
Applications
Magnetic amplifiers were used extensively as the switching element in early switched-mode (SMPS) power supplies[1], as well as in lighting control. They have been largely superseded by semiconductor based solid-state switches, though recently there has been some regained interest in using mag amps in compact and reliable switching power supplies. PC ATX power supplies often use mag amps for secondary side voltage regulation.Magnetic amplifier transformer cores designed specifically for switch mode power supplies are currently manufactured by several large electromagnetics companies, including Metglas and Mag-Inc.
Magnetic amplifiers can be used for measuring high DC-voltages without direct connection to the high voltage and are therefore still used in the HVDC-technique.
References
External links
- Magnetic Amplifier Control for Simple, Low-Cost, Secondary Regulation - B. Mammano, Texas Instruments Seminar 500
- MAG-AMP Magnetic Amplifiers Intro, Butlerwinding
Electromagnetism is the physics of the electromagnetic field: a field which exerts a force on particles that possess the property of electric charge, and is in turn affected by the presence and motion of those particles.
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twentieth century of the Common Era began on January 1, 1901 and ended on December 31, 2000, according to the Gregorian calendar. Some historians consider the era from about 1914 to 1991 to be the Short Twentieth Century.
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vacuum tube, electron tube (inside North America), thermionic valve, or just valve (elsewhere); is a device used to amplify, switch, otherwise modify, or create an electrical signal by controlling the movement of electrons in a low-pressure space, often not
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Allied powers:
Soviet Union
United States
United Kingdom
China
France
...et al. Axis powers:
Germany
Japan
Italy
...et al.
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Soviet Union
United States
United Kingdom
China
France
...et al. Axis powers:
Germany
Japan
Italy
...et al.
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Anthem
"Das Lied der Deutschen" (third stanza)
also called "Einigkeit und Recht und Freiheit"
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"Das Lied der Deutschen" (third stanza)
also called "Einigkeit und Recht und Freiheit"
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Function single stage ballistic missile (area bombing)
Manufacturer Mittelwerk GmbH (development by Army Research Center Peenemünde)
Unit cost 100,000 RM January 1944, 50,000 RM March 1945[1]
Entered service 1944
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Manufacturer Mittelwerk GmbH (development by Army Research Center Peenemünde)
Unit cost 100,000 RM January 1944, 50,000 RM March 1945[1]
Entered service 1944
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A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. The transistor is the fundamental building block of the circuitry in computers, cellular phones, and all other modern electronic devices.
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transformer is a device that transfers electrical energy from one circuit to another through inductively coupled wires. A changing current in the first circuit (the primary
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saturable reactor in electrical engineering is a special form of inductor where the magnetic core can be deliberately saturated by means of a dc current flowing in a control winding. Once saturated, the inductance of the saturable reactor drops dramatically.
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For magnetic materials, saturation is the state when the material cannot absorb a stronger magnetic field, such that an increase of magnetization force produces no significant change in magnetic flux density.
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The magnetic core is a key component in electrical devices such as electromagnets, transformers and inductors. Its role is to increase the strength and effect of magnetic fields produced by electric currents.
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SMPS may refer to:
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- Single member plurality system
- Switched-mode power supply
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HVDC or high-voltage, direct current electric power transmission systems contrast with the more common alternating current systems as a means for the bulk transmission of electrical power.
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