An Improved Parasitic Capacitance Cancellation Method for Planar Differential Mode Inductor in EMI Filters

Power semiconductor components with high switching speed are widely used in static converters. However, they produce conducted electromagnetic interferences in high frequencies. Filters are one solution for reducing the conducted emissions. However, the parasitic elements of the passive components in the EMI filter deteriorate its performances. In this paper, we propose to study a differential mode (DM) inductor in planar technology. The goal is to reduce the parasitic capacitance of the planar DM inductor via an improved parasitic capacitance cancellation technique. The technique is based on the results of an analytical method using Electric Field Decomposition and energy based approach. The cancellation is then realized through the structural parasitic capacitances under an optimal geometry configuration. The efficiency of the proposed cancellation technique is validated by measurements.