Asymmetrical Current Distribution in Metallized Film Capacitors

International audienceThe presence of high frequency currents in the vicinity of metallized capacitors can generate eddy currents in the metallizations, with a possible negative impact on the reliability and lifetime of these components. These phenomena are due to the asymmetrical distribution of the field lines. We present a model derived from the physical relations between the current density, the strength of the magnetic field, the electromotive force in a capacitor winding and its plates, and the conductivity of the different materials. This model also takes into account anisotropy due to the structure of the winding. The results obtained from this model can be compared to the measurements of the electromotive force detected by a loop in the vicinity of a capacitor under operation. Finally, the consequences of nonsymmetrical magnetic field distribution are discussed in the light of the results obtained from the model