A Modular Fractional-order Circuit Model for Broadband Impedance Characterization of Polymeric Insulation Systems

Power assets driven by semiconductor devices are developing towards high-voltage (HV), miniaturization, and high-power density, which are posing serious threats, e.g., electrothermal stresses on insulation systems as the weakest points. Therefore, modeling impedance characteristics of insulation systems is a crucial step to support the insulation design and reliability analysis of HV power assets. This paper proposes a modular broadband impedance characteristic modeling approach for insulation systems, which can apply to multifrequency applications. The proposed new impedance circuit model fully considers the intrinsic conductance behavior and relaxation mechanisms of insulation systems over broadband frequencies. Meanwhile, the fractional calculus theory is introduced to assist in modeling the frequencydependent dielectric response characteristics for nonideal insulation systems. The new circuit model is based on in-depth physical insights and is modular and user-friendly. It enables a better representation of the broadband impedance characteristics of insulation systems.