A novel implementation of perturbation technique for better integration of NUTL with periodic geometry

In this work, a novel implementation of the perturbative technique (PT) recently proposed in [1] for the solution of nonuniform transmission-lines (NUTLs) is presented. Unlike the original PT, the proposed method provides a 2n-port Sparameter representation of the NUTL under analysis, which can be afterwards used in combination with different terminal conditions and/or cascaded with other 2n-port networks. As an application example, an interdigital tabbed microstrip line terminated in SMA connectors and involving a bend discontinuity is solved by the proposed technique. The obtained predictions are validated versus those provided by a full-wave solver

Approximate Transmission-Line Model for Field-to-Wire Coupling in Arbitrarily Routed Wiring Structures Above Ground

In this article, a comprehensive method for parametric representation of wire trajectories, allowing accurate geometric description of complex and arbitrarily oriented wire bundles, is introduced. This is the starting point to develop a computationally efficient numerical transmission-line (TL) model for predicting the radiated susceptibility of arbitrarily oriented bundles of wires, illuminated by (possibly) nonuniform electromagnetic fields. The proposed method foresees solution of the field-to-wire coupling problem through suitable discretization and sampling of the bundle geometry and the incident electromagnetic field. Differently from previous models, where bundles parallel to ground were assumed, the proposed model allows for arbitrary bundle orientation by exploiting, first, exact projection of the external field onto the bundle direction, and second, evaluation of the actual wire length (instead of the longitudinal one) of each TL section. Accuracy and computational efficiency of the proposed method are assessed versus full-wave simulation for two application examples, involving parabola-shaped and trefoil knot-shaped wiring structures above ground. Although the strong nonuniformity affecting these structures forces TL theory to work very close to its limits, the achieved agreement is satisfactory and the significant reduction of computational times makes the proposed method suitable for approximate yet efficient prediction of radiated susceptibility characteristics of complex wire bundles

Prediction of EMI Filter Attenuation in Power-Electronic Converters via Circuit Simulation

This article investigates the conducted-emission (CE) suppression characteristics of electromagnetic interference (EMI) filters used in power-electronic equipment by time-domain circuit simulation. An operational definition of insertion attenuation is introduced by comparing the CE in the absence and in the presence of the EMI filter. For the sake of exemplification, the analysis focuses on switched-mode dc-dc converters. It is shown that the EMI-filter attenuation behaves differently from the standard insertion loss (IL) and exhibits peculiar properties in these circuits. Namely, its response is known at discrete frequencies where the converter generates CE and may strongly depend on the harmonic index so to jump between quite different levels from a harmonic component to the next one, with a pseudoperiodic behavior, which can be related to the duty cycle. This effect is caused by circuit nonlinearity and is partially mitigated if the simulation accounts for two practically relevant aspects: random instability of the duty cycle and resolution bandwidth of the EMI receiver. The dependence of the common-mode (CM) and differential-mode attenuations on the loading conditions and duty cycle is analyzed, and it is shown that linear IL models provide reasonable predictions of CM attenuation only. Finally, experimental evidence of the unveiled phenomena is presented

Enhanced Impedance Measurement to Predict Electromagnetic Interference Attenuation Provided by EMI Filters in Systems with AC/DC Converters

Due to the widespread integration of renewable energy sources connected to AC and DC power systems by means of power electronics converters, electromagnetic noise propagates along lines, and metallic earth-return structures. EMI filters are commonly used to mitigate the common mode and differential mode noise at the interface of distribution lines, and their suppression characteristics are usually assessed in standard test setups, the impedances of which are, however, scarcely representative of real-world applications. In this paper, an online, inductively coupled impedance measurement method is proposed. A sensitivity analysis to highlight the benefits of the proposed setup and experimental verification is performed. The proposed method enables non-intrusive impedance measurement in energized systems, including power converters. These measures, in turn, allow the evaluation of modal insertion losses of EMI filters in real-world operating conditions. The three-phase example considered in this study shows significant deviations from manufacturer specifications, thus justifying the need for more advanced estimation techniques