Analysis of Approaches for Reduction of the Parasitic Capacitances in Transformers with Copper Foil Windings for Fast Switching Applications

Inhalt:
Due to the fact that wide bandgap semiconductors offer the possibility of very steep switching transients, transformers have to be correspondingly adapted. Otherwise, high dv/dt-values can lead to displacement currents with disturbingly high magnitudes through the parasitic capacitances of a transformer. Three approaches for the reduction of these capacitances have been investigated by simulation and partially validated by measurements. Regarding the winding-to-core capacitance, optimizing the shape of the copper foil winding can be a beneficial approach to reduce the capacitance value. In order to decrease the winding capacitance, cutting holes in the copper foil and utilizing a varying thickness of the isolation material between the turns are two further promising approaches.