Circuits équivalents pour transformateurs multienroulements : Application à la CEM conduite d'un convertisseur
The work presented in this report refers to the search of equivalent circuits with lumped constants to represent the electric behavior of the transformers. It falls under the continuity of a long study, started in 1988 and undertaken in collaboration with several industrialists. It generalizes former work and leads to the representation of the multiwinding transformers. General methods of representation and experimental identification of the multiwinding transformers are established. For that purpose, from the general reference marks concerning the number of measurable impedances, the number of poles and zeros of these impedances are disengaged. New concepts, such as the leakage transformer and progressive modeling, are introduced. An analytical model is developed to take into account for the effects of the induced currents (skin and proximity) in the conductors. A solution is proposed to solve the problem of the representation of these effects by lumped constants. AlI this is validated in experiment and, in margin of this work, a bench intended to characterize the magnetic radiation of the magnetic components is studied and tested successfully. The interest of preceding work is illustrated by the study of an indus trial converter. It proves that the imperfections of the transformer using three windings, (weIl represented by the equivalent circuit) very strongly influence the dimensioning of the other components and the disturbances of common mode of the converter. It is thus shown that a precise model of transformer is a key element to design a reliable power converter and in conformity with the standards of electromagnetic compatibility.