The Parametric transformer (or paraformer) is a particular type of
transformer
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
. It transfers the
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
from primary to secondary
windings
An electromagnetic coil is an electrical conductor such as a wire in the shape of a coil (spiral or helix). Electromagnetic coils are used in electrical engineering, in applications where electric currents interact with magnetic fields, in de ...
not by
mutual inductance coupling but by a variation of a parameter in its
magnetic circuit
A magnetic circuit is made up of one or more closed loop paths containing a magnetic flux. The flux is usually generated by permanent magnets or electromagnets and confined to the path by magnetic cores consisting of ferromagnetic materials l ...
. First described by Wanlass, ''et al.'', 1968.
Assuming
Faraday's law of induction
Faraday's law of induction (briefly, Faraday's law) is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (emf)—a phenomenon known as electromagnetic inducti ...
,
it is possible to obtain a
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
at the secondary winding terminals also thanks to a variation of the inductance, so that
This can be accomplished by for example modulating the
saturation
Saturation, saturated, unsaturation or unsaturated may refer to:
Chemistry
* Saturation, a property of organic compounds referring to carbon-carbon bonds
**Saturated and unsaturated compounds
** Degree of unsaturation
**Saturated fat or fatty aci ...
of the core by means of an applied variable
magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
. It works even if primary and secondary windings magnetic coupling is zero (when the
fluxes are mutually
orthogonal
In mathematics, orthogonality is the generalization of the geometric notion of ''perpendicularity''.
By extension, orthogonality is also used to refer to the separation of specific features of a system. The term also has specialized meanings in ...
) (Burian 1972, p. 278).
Further reading
*S. D. Wanlass, C. L. Wanlass, L. K. Wanlass, "The Paraformer; A new passive power conversion device", ''IEEE Wescon Tech. Papers'', 1968.
*Burian, Kurt
"Theory and analysis of a parametrically excited passive power converter" ''IEEE Transactions on Industry Applications'', vol. IA-8, iss. 3, pp. 278–282, May 1972.
*Power, Henry Al
"Analysis of a passive power converter as a nonlinear feedback system" ''IEEE Transactions on Industry Applications'', vol. IA-11, iss. 5, pp. 556–559, September 1975.
*Bessho, K.; Matsumura, F.; Aoki, Y.; Suzuki, M.
"Theory and analysis of a new power converter with center-tap reactor circuit" ''IEEE Transactions on Magnetics'', vol. 11, iss. 5, pp. 1558–1560, September 1975.
*Tez, E. Salih; Smith, I. R.
The Parametric transformer: a power conversion device demonstrating the principles of parametric excitation" ''IEEE Transactions on Education'', vol. 27, iss. 2, pp. 56–57, May 1984 (includes history of the principle).
*Newark Electronics
"Newark-Denver Electronic Supply Co., Wanlass Parax Voltage Regulators and Paraformer"Wanlass "Parax Voltage Regulators and Paraformer," Newark-Denver Electronic Supply Company 1970 catalog pg. 252. Archived at Pro Audio design Forum.
Electric transformers
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