The Parametric transformer (or paraformer) is a particular type of
transformer. It transfers the
power from primary to secondary
Windings not by
mutual inductance coupling but by a variation of a parameter in its
magnetic circuit. First described by Wanlass, et al., 1968.
it is possible to obtain a
voltage 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 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
fluxes are mutually
orthogonal) (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.