1,721,087 research outputs found
Alternative radiated susceptibility test methods at unit level
Full text linkThis article briefly illustrates and discusses the possibility to develop alternative, simplified test methods for radiated susceptibility testing at unit level for the aerospace sector. The rationale here discussed, and the alternative test methods here illustrated, are targeted to the development of a testing approach with deeper physics' sense, quicker and less expensive in order to help the industrial design process of equipment for spacecraft. The theoretical basis of this analysis is the possibility to enforce equivalence (in terms of common mode current) among the effects due to field-to-wire-coupling, bulk current injection and crosstalk, under suitable assumptions. Two dual approaches are considered, one aimed at achieving deterministic equivalence, the other enforcing equivalence in statistical terms. Pros and cons of the proposed alternative test methods are discussed by illustrating the outcomes of ad hoc setups and a wide experimental campaign
Field-to-Wire Coupling in Bundles of Wires: Comparison between Different Models
Full text linkIn this paper, the electromagnetic disturbances induced by a plane-wave field in random wire bundles routed in close proximity with a ground plane is investigated by adopting a statistical approach. Accurate geometrical description of the random trajectories of the wires is used in combination with a multiconductor transmission line model of the bundle involving fine segmentation into a sequence of uniform cascaded sections. Repeated-run analysis is then adopted for reproduction of the frequency response of the voltages induced across the terminal loads. The outcomes of this analysis are compared versus a modeling approach previously developed and based on a more approximate representation of the wire trajectories. It is shown that the ability to reproduce smooth wire trajectories (mimicking the shape of wires in real bundles) is important in order to avoid artifacts in the frequency response, at specific frequencies, and lead to induced voltages which, at high frequencies, show probability density functions with different shape
Measurement-Based Equivalent Circuit Model for Time-Domain Simulation of EMI Filters
Full text linkIn this paper, a methodology to derive equivalent circuits of EMI filters from S-parameters is introduced and discussed. Starting from measured S-parameters and with no need for information on the internal structure of the filter, a rational approximation of the measured frequency responses is derived and equivalent circuits are directly synthesized. The proposed black-box filter models are compatible with SPICE solvers and can be used, in combination with component-level representations of power-electronic equipment, for the prediction of conducted emissions through time-domain simulation. As an example of usage, a CISPR-25 test setup where the EMI filter operates in the presence of an inverter is discussed
Accurate Geometrical Modeling and Field-to-Wire Coupling Prediction in Wiring-Structures with Loops
Full text linkIrregular-shaped wiring structures are usually encountered in practical applications. In this work, a wiring structure encompassing a loop is modeled geometrically by resorting to a 3D cylindrical helix. To predict the disturbances induced by an incident electromagnetic field at the terminals of such a nonuniform structure, a simplified numerical solution based on transmission-line (TL) theory is developed. To this end, the structure is discretized in segments and the Agrawal TL model is formulated by accounting for the actual orientation of each wire segment with respect to the incident electric field vector. Full-wave simulations of the current induced in the terminations of the wiring structure under analysis are used to validate the accuracy of the proposed numerical TL-based method as well as its computational effectiveness
Prediction of EMI Filter Attenuation in Power-Electronic Converters via Circuit Simulation
Full text linkThis 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
S-parameter characterization of nonuniform microstrip lines via perturbative technique
Full text linkThis paper presents a frequency-domain perturbative technique for the solution of nonuniform transmission-lines (NUTLs), resorting to a preliminary S-parameter characterization. According to this method, the NUTL S-parameter matrix is obtained column-by-column, by solution of NUTL subproblems involving different terminal networks. The procedure results to be particularly suitable in the case of differential lines with fully or partially repetitive geometry, since it allows good prediction accuracy and reduced computational burden. As explicative examples, the technique is here applied to high-speed microstrip line configurations for common-mode suppression
Coupling of Wideband Radiated IEMI to Cables above Ground
No full textIn this paper, transmission-line (TL) theory is applied to formulate a worst-case analysis for the assessment of wideband intentional electromagnetic interference radiated onto a cable harness (with terminal units) above ground. Given the bandwidth and the energy density of the high-power electromagnetic pulse impinging on the cable, the pulse spectrum maximizing the peak value of the common-mode voltage waveform induced at a cable end is obtained. Unlike in a full-wave solution to the problem, the proposed TL model allows for, first, deriving closed-form expressions in the special case of a cable terminated in a matched load at the opposite end; second, computationally efficient evaluation of the spectrum for any other loading conditions. The obtained results clearly unveil the impact of the system parameters (cable length, height, terminal loads, and pulse bandwidth) on the statistics of the worst-case voltage peak for the random direction of incidence and polarization
Physically Based Modeling of Hand-Assembled Wire Bundles for Accurate EMC Prediction
Full text linkIn this paper, a new modeling approach to generate wire bundles with geometry accurately mimicking the random displacements of the wires in real, hand-assembled bundles is proposed. To this end, the wire trajectories are modeled by three-dimensional (3-D) curves that retain continuity of the wire path and its first derivative, allow enforcing random fluctuations of wire position in the bundle cross section and controlling bundle density. An iterative algorithm involving both local and global perturbations of initially generated trajectories is used to prevent wire overlapping. As a whole, the proposed modeling approach is able to reproduce (through the use of a limited number of parameters) the main physical properties of real hand-assembled wire bundles. In order to get either deterministic or statistical estimates of the electromagnetic compatibility performance, the obtained bundle geometry can be easily imported into 3-D electromagnetic solvers or modeled as a multiconductor transmission line by approximating the nonuniform wire paths as a sequence of uniform cascaded sections. Application examples aimed at the prediction of crosstalk and field-to-wire coupling are used to prove the importance of accurate modeling of the bundle geometry and proper digitization of the bundle along its length for prediction at high frequencies of the electromagnetic noise induced in the terminal units
Black-Box Modeling of EMI Filters for Frequency and Time-Domain Simulations
Full text linkA procedure for the derivation of a black-box model of electromagnetic interference (EMI) filters is proposed and discussed. The modeling approach is assessed by resorting to a real EMI filter. The equivalent circuit of the filter is directly obtained from a rational approximation of the scattering-parameter matrix measured at the filter ports. Therefore, the modeling procedure does not require any information on the internal structure of the filter (e.g., components, electrical/magnetic properties of the involved materials, connections leads, etc.). The circuit model is compatible with SPICE solvers and can be used for the prediction of conducted emissions in both the frequency and time domain. Specifically, the proposed modeling approach allows time-domain simulation and performance analysis of EMI filters in combination with power-electronic equipment (i.e., nonlinear, time-variant circuits)
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