en>David Eppstein: /* Properties */ another ref

2014-04-09T18:41:29Z

Properties: another ref

en>Khazar2: clean up, typos fixed: merging together → merging, added orphan tag using AWB

2012-05-29T23:48:08Z

clean up, typos fixed: merging together → merging, added orphan tag using AWB

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The '''paraformer''' is a particular type of [[transformer]]. It transfers the [[electric power|power]] from primary to secondary [[transformer#windings|windings]] not by [[Inductance#Coupled inductors|mutual inductance coupling]] but by a variation of a parameter in its [[magnetic circuit]]. First described by Wanlass, ''et al.'', 1968.

Assuming [[Faraday's law of induction]],

<math>v(t) = L \frac{di(t)}{dt} </math>

it is possible to obtain a [[voltage]] at the secondary winding terminals also thanks to a variation of the inductance, so that

<math>v(t) = I \frac{dl(t)}{dt} </math>

This can be accomplished by for example modulating the [[Saturation (magnetic)|saturation]] of the core by means of an applied variable [[magnetic field]]. It works even if primary and secondary windings magnetic coupling is zero (when the [[magnetic flux|fluxes]] are mutually [[orthogonal]]).{{Citation needed|date=August 2009}}

==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, [http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4158243 "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, [http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4157787 "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., [http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1058824 "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., [http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4321665 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).

[[Category:Transformers (electrical)]]

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en>David Eppstein: /* Properties */ another ref

en>Khazar2: clean up, typos fixed: merging together → merging, added orphan tag using AWB