Numerical modeling and analysis of complex electromagnetic structures, including those containing ferrites

Application of fast switching amplifiers in power converters, and especially in power inverters, causes unwanted radiated emission, which is a consequence of common mode (CM) currents arising in feed wire bundles. Ferrite chokes are commonly used to suppress those CM currents by increasing the CM impedance of circuits without affecting the differential mode currents, which is important for undisturbed operation of the converters or inverters. Their effective impedance is the main design concern, and it is determined by the material intrinsic properties (permeability, permittivity) and geometry. The goal of this work is to analytically correlate the geometrical and material properties (permittivity and magnetic permeability) of a ferrite choke under test conditions with its extracted equivalent circuit parameters (resistance, inductance and capacitance) and complex impedance of the ferrite choke on a wire bundle. The identification of those above mentioned equivalent circuit parameters can help to identify the best combination of dimension-material properties to maximize the efficiency of ferrites for suppressing CM currents --Abstract, page iii