Effect of different winding patterns on parasitic capacitance in common mode chokes

Wide-bandgap devices including silicon carbide (SiC) exacerbate electromagnetic compatibility issues in electric propulsion systems. Accurate modelling of the filter components is of great importance. The parasitic capacitance in the common mode choke has a major influence on the high-frequency noise suppression performance, and is determined by several factors, including the material permittivity, the geometric parameters and the winding patterns. The influence of winding patterns remains understudied. This study addresses this gap by analysing two chokes winding patterns: sectional and bifilar windings. Physics-based models derive parasitic capacitance expressions for sectional and bifilar winding chokes. Voltage difference positively correlates with capacitance of bifilar windings choke, and its application scope is defined. Experiments validate models, showing bifilar chokes outperform sectional counterparts in low-voltage difference scenarios.