Showing papers on "Electromagnetic compatibility published in 2007"

Applications of the Near-Field Techniques in EMC Investigations

Abstract: A completely automatic near-field mapping system has been developed within the Research Institute for Electronic Embedded Systems (IRSEEM) in order to determine the electromagnetic field created by electronic systems and components. This test bench uses a 3-D positioning system of the probe to make accurate measurements. This paper presents some applications of the near-field techniques in EMC investigations. In the first part, near-field measurements are used to locate precisely the electromagnetic sources of a limiter device. In the second part, we present an equivalent model of the radiated emission of an integrated circuit. In the last part, the near-field test bench is used to characterize faults in a cable.

A Three-Dimensional Semi-Implicit FDTD Scheme for Calculation of Shielding Effectiveness of Enclosure With Thin Slots

Abstract: The hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) scheme for a 2-D transverse electric (TE) wave is extended to a full 3-D electromagnetic wave in this paper. With the weakly conditional stability, this approach simulates shielding effectiveness of an enclosure with high computation efficiency. Numerical formulations of the 3-D HIE-FDTD scheme are presented, and simulation results are compared to those obtained by using the conventional 3-D FDTD and alternating-direction implicit (ADI) FDTD methods. The accuracy and efficiency of the 3-D HIE-FDTD for prediction of shielding effectiveness are validated by numerical simulation results.

Advanced Modeling in Computational Electromagnetic Compatibility

Abstract: The book is divided in three parts. The first part deals with introductory topics in EMC, namely, it is concerned with the fundamentals of electromagnetic theory, basics in numerical modeling and simple computational models in the analysis of static, quasistatic and scattering problems. The second part of the book deals with an analysis of the wire antennas using the frequency domain (FD) and the time domain (TD) integral equation formulation, respectively. Finally, the third part of the book deals with the solution of some specific EMC problems by means of the wire antenna theory presented in Part II.

Principles and Techniques of Electromagnetic Compatibility

Abstract: Circuits are faster and more tightly packed than ever, wireless technologies increase the electromagnetic (EM) noise environment, new materials entail entirely new immunity issues, and new standards govern the field of electromagnetic compatibility (EMC). Maintaining the practical and comprehensive approach of its predecessor, Principles and Techniques of Electromagnetic Compatibility, Second Edition reflects these emerging challenges and new technologies introduced throughout the decade since the first edition appeared. What's new in the Second Edition? Characterization and testing for high-speed design of clock frequencies up to and above 6 GHz Updates to the regulatory framework governing EM compliance Additional coverage of the printed circuit board (PCB) environment as well as additional numerical tools An entirely new section devoted to new applications, including signal integrity, wireless and broadband technologies, EMC safety, and statistical EMC Added coverage of new materials such as nanomaterials, band gap devices, and composites Along with new and updated content, this edition also includes additional worked examples that demonstrate how estimates can guide the early stages of design. The focus remains on building a sound foundation on the fundamental concepts and linking this to practical applications, rather than supplying application-specific fixes that do not easily generalize to other areas.

Electromagnetic models of the lightning return stroke

Abstract: [1] Lightning return-stroke models are needed for specifying the source in studying the production of transient optical emission (elves) in the lower ionosphere, the energetic radiation from lightning, and characterization of the Earth's electromagnetic environment, as well as studying lightning interaction with various objects and systems. Reviewed here are models based on Maxwell's equations and referred to as electromagnetic models. These models are relatively new and most rigorous of all models suitable for computing lightning electromagnetic fields. Maxwell's equations are numerically solved to yield the distribution of current along the lightning channel. Different numerical techniques, including the method of moments (MoM) and the finite difference time domain (FDTD) method, are employed. In order to achieve a desirable current-wave propagation speed (lower than the speed of light in air), the channel-representing wire is embedded in a dielectric (other than air) or loaded by additional distributed series inductance. Capacitive loading has been also suggested. The artificial dielectric medium is used only for finding the distribution of current along the lightning channel, after which the channel is allowed to radiate in air. Resistive loading is used to control current attenuation with height. In contrast with distributed circuit and so-called engineering models, electromagnetic return-stroke models allow a self-consistent full-wave solution for both lightning-current distribution and resultant electromagnetic fields. In this review, we discuss advantages and disadvantages of four return-stroke channel representations: a perfectly conducting/resistive wire in air, a wire embedded in a dielectric (other than air), a wire in air loaded by additional distributed series inductance, and a wire in air having additional distributed shunt capacitance. Further, we describe and compare different methods of excitation used in electromagnetic return-stroke models: closing a charged vertical wire at its bottom with a specified grounded circuit, a delta-gap electric field source, and a lumped current source. Finally, we review and compare representative numerical techniques used in electromagnetic modeling of the lightning return stroke: MoMs in the time and frequency domains and the FDTD method. We additionally consider the so-called hybrid model of the lightning return stroke that employs a combination of electromagnetic and circuit theories and compare this model to electromagnetic models.

Fast and Rigorous Analysis of EMC/EMI Phenomena on Electrically Large and Complex Cable-Loaded Structures

Abstract: A fast and comprehensive time-domain method for analyzing electromagnetic compatibility (EMC) and electromagnetic interference (EMI) phenomena on complex structures that involve electrically large platforms (e.g., vehicle shells) along with cable-interconnected antennas, shielding enclosures, and printed circuit boards is proposed. To efficiently simulate field interactions with such structures, three different solvers are hybridized: (1) a time-domain integral-equation (TDIE)-based field solver that computes fields on the exterior structure comprising platforms, antennas, enclosures, boards, and cable shields (external fields); (2) a modified nodal-analysis (MNA)-based circuit solver that computes currents and voltages on lumped circuits approximating cable connectors/loads; and (3) a TDIE-based transmission line solver that computes transmission line voltages and currents at cable terminations (guided fields). These three solvers are rigorously interfaced at the cable connectors/loads and along the cable shields; the resulting coupled system of equations is solved simultaneously at each time step. Computation of the external and guided fields, which constitutes the computational bottleneck of this approach, is accelerated using fast Fourier transform-based algorithms. Further acceleration is achieved by parallelizing the computation of external fields. The resulting hybrid solver permits the analysis of electrically large and geometrically intricate structures loaded with coaxial cables. The accuracy, efficiency, and versatility of the proposed solver are demonstrated by analyzing several EMC/EMI problems including interference between a log-periodic monopole array trailing an aircraft's wing and a monopole antenna mounted on its fuselage, coupling into coaxial cables connecting shielded printed circuit boards located inside a cockpit, and coupling into coaxial cables from a cell phone antenna located inside a fuselage.

Application of Random PWM Technique for Reducing the Conducted Electromagnetic Emissions in Active Filters

Abstract: A pulsewidth modulation (PWM)-controlled active filter generates harmonics at the switching frequency and its multiples in the RF range, and the concentrated power spectrum may produce electromagnetic interference (EMI) problems. In this paper, the random PWM (RPWM) technique is applied in order to spread the noise spectrum over a wide range, thus, considerably reducing the amplitudes of these harmonics and the consequent EMI problems. To study the operation of active filters, the case of an ac/dc converter along with a power-factor corrector is considered as a nonlinear load and a series active filter, respectively. A line impedance stabilization network is used to study the RF noise emanating from the converter. A noise model to study the EMI emission is presented and used in this paper. Theoretical analysis of the RF noise power spectrum is carried out in order to demonstrate the advantages of the RPWM technique over conventional PWM. Experimental results confirm the validity of the theoretical calculations and simulation results, and demonstrate the effectiveness of applying the RPWM technique in reducing the RF noise level.

EMI Suppression in Voltage Source Converters by Utilizing dc-link Decoupling Capacitors

Abstract: Direct current (dc)-link decoupling capacitors are normally used to control the voltage overshoot of switching devices in voltage source converters. This paper analyzes decoupling capacitors' impacts on device electromagnetic interference (EMI) noise as well as on device voltage stress. The design and selection of decoupling capacitors considering both voltage stress and EMI suppression are presented. A new high-frequency EMI filter by utilizing the decoupling capacitors is proposed. The filter is adopted as a local EMI filter for power modules. The integratable characteristics of the proposed filter are discussed. Simulation and experimental results verify the design. This high-frequency filter shows good attenuation for high-frequency EMI noise and voltage overshoot suppression.

Modelling the electrical properties of concrete for shielding effectiveness prediction

Abstract: Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands a detailed understanding of its electrical properties. Besides experimental measurements, material theoretical models can be useful to investigate its behaviour with respect to frequency, moisture content or other factors. These models can be used in electromagnetic compatibility (EMC) to predict the shielding effectiveness of a concrete structure against external electromagnetic waves. This paper presents the development of a dispersive material model for concrete out of experimental measurement data to take account of the frequency dependence of concrete's electrical properties. The model is implemented into a numerical simulator and compared with the classical transmission-line approach in shielding effectiveness calculations of simple concrete walls of different moisture content. The comparative results show good agreement in all cases; a possible relation between shielding effectiveness and the electrical properties of concrete and the limits of the proposed model are discussed.

Novel Planar Electromagnetic Bandgap Structures for Mitigation of Switching Noise and EMI Reduction in High-Speed Circuits

Abstract: Planar electromagnetic bandgap (EBG) structures with novel meandered lines and super cell configuration are proposed for mitigating simultaneous switching noise propagation in high-speed printed circuit boards. An ultrawide bandgap extending from 250 MHz to 12 GHz and beyond is demonstrated by both simulation and measurement, and a good agreement is observed. These perforated EBG-based power planes may cause spurious and unwanted radiation. In this paper, leakage radiation through these imperfect planes is carefully investigated. It is found that the leakage field from these planar EBG structures is highly concentrated around the feed point, and the field intensity is attenuated dramatically when passing across several periods of patches. A novel concept of using these EBG structures for electromagnetic interference reduction is also introduced. Finally, the impact of power plane with EBG-patterned structures on signal integrity is studied.

Characterisation of electromagnetic susceptibility of integrated circuits using near-field scan

Abstract: A susceptibility characterisation test for integrated circuits using a miniature magnetic near-field probe is described. The method is efficient up to a frequency of 6 GHz and maps immunity to radiated fields.

Numerical Electromagnetic Field Analysis for EMC Problems

Abstract: Much progress has been made in the use of computational electromagnetics for the analysis of electromagnetic compatibility (EMC) problems during recent years. This paper reviews the improvements in some of the most important techniques of the field: the method of moments, the finite-difference time-domain method, the finite-element method, the transmission-line matrix method, and the partial-element equivalent-circuit method. The results of computer codes on the basis of such methods have to be validated, and some of the respective possibilities are addressed.

Improvement of Electromagnetic Compatibility of Motor Drives Using Chaotic PWM

Abstract: In this paper, a new chaotic pulse width modulation (PWM) scheme is proposed and implemented to reduce the conducted electromagnetic interference (EMI) in motor drives The key is the use of logistic mapping to chaoize a frequency-modulated signal which then modulates the carrier frequency Compared with the sinusoidal PWM and random PWM, the proposed scheme not only suppresses the peaky EMI, but also avoids the occurrence of low-order noises and mechanical resonance Both simulation and experimental results are given to support the validity

Fast Emission Measurement in Time Domain

Abstract: According to the applicable standards, electromagnetic compatibility emission measurements are carried out in the frequency domain using a measuring receiver. In this paper, the theory, setup, and algorithms, as well as the practical aspects including the examples of a precompliance measuring system in the time domain, are presented. The advantage of this system is that the measurements can be carried out approximately 10-100 times faster with sufficient accuracy and signal-to-noise ratio in the detector modes peak, quasi-peak, and average.

Closed-Form Expressions for the Electromagnetic Radiation of Microstrip Signal Traces

Abstract: An analytical study of the unintentional electromagnetic radiation of a microstrip signal trace is presented. Based on transmission-line theory and appropriate far-field Green's functions, a closed-form solution for the electric field is developed, including the contribution from the vertical terminal connections. It allows calculating the frequency and directional response of the radiated emission, depending on the material and geometrical parameters and terminal load impedances. For the special case of matched termination, the general solution assumes a compact form, allowing to set up a formula for the peak-amplitude frequencies. It is shown that in the higher frequency region, where the wavelength is comparable or shorter than the line length, the frequency-response envelope continuously rises with 20 dB/dec. Based on appropriate simplifications, the asymptotic solution for the electrically short line is deduced, including a practical formula for the maximum electric field. It is found that the usual small-current-loop (magnetic-dipole) estimation is incomplete due to the omission of the electric-dipole contribution.

A Brief History of Work in Transmission Lines for EMC Applications

Abstract: A brief chronology of the application of transmission line theory to electromagnetic compatibility (EMC) applications is presented. Transmission line studies in EMC began in the 1950s and 1960s with the frequency-domain analysis of crosstalk in cables. Nuclear electromagnetic pulse (EMP) concerns in the 1970s caused an increasing emphasis on the study of incident field excitation of the lines. The advent of digital technology in the 1980s moved the research emphasis toward the analysis of the transmission lines in the time domain. Early work concentrated on lossless lines whose solutions are very simple. After the 1980s, the impact of high-speed digital technology has driven much of the research toward the study of ways to incorporate line losses (particularly, frequency-dependent losses as with skin effect) into the solutions. In addition, the increasingly complex digital systems have resulted in the study of how to optimize the representation and solution of large interconnected networks of transmission lines. This paper attempts to put the historical evolution of the study of transmission lines in EMC in a chronological perspective.

Analysis of an Electromagnetic Field Created by Line Current Using Constrained Interpolation Profile Method

Abstract: Development of accurate schemes is a technical issue related to calculation of electromagnetic fields. This study uses constrained interpolation profile (CIP) method to analyze electromagnetic fields created by line current. This is a novel method proposed by Yabe. Comparison of results obtained using finite difference time domain (FDTD) analysis and CIP analysis indicates that CIP analysis provides higher accuracy using identical discretization. In addition, given the same level of accuracy, CIP analysis requires less memory and less calculation time

EMC Assessment at Chip and PCB Level: Use of the ICEM Model for Jitter Analysis in an Integrated PLL

Abstract: This paper deals with the use of the integrated circuit electromagnetic model (ICEM) to analyze, predict, and optimize autocompatibility and electromagnetic emission at chip and system level. ICEM is currently under standardization process (IEC62014-3). The basic ICEM architecture is composed of a power distribution network model and an internal current source modeling digital activity. Such an approach enables the description of any kind of digital or mixed-signal design. This model is useful either for the IC manufacturer or the system manufacturer. The power distribution network of a printed circuit board (PCB) can be optimized using this model by choosing the number and the right values of decoupling capacitors as well as the size of power planes. The IC manufacturer may check out the autocompatibility of an IC and determine the number of power pins as well as the package to be used. As an example, jitter analysis of an integrated phase-locked-loop can be performed using ICEM. This paper demonstrates that this jitter can be predicted by simulation and that corrective solutions can be provided and checked out before implementation

EM simulation accuracy enhancement for broadband modeling of on-wafer passive components

Abstract: This paper describes methods for accuracy enhancement in broadband modeling of on-wafer passive components using electromagnetic (EM) simulation. It is shown that standard excitation schemes for integrated component simulation leads to poor correlation with on-wafer measurements beyond the lower GHz frequency range. We show that this is due to parasitic effects and higher-order modes caused by the excitation schemes. We propose a simple equivalent circuit for the parasitic effects in the well-known ground ring excitation scheme. An extended L-2L calibration method is shown to improve significantly the accuracy of the on-wafer component modeling, when applied to parasitic effect removal associated with the excitation schemes.

Numerical Prediction and Measurement of ESD Radiated Fields by Free-Space Field Sensors

Abstract: This paper describes the evaluation of electric and magnetic fields due to electrostatic discharges (ESDs) using an efficient numerical prediction model and measurements obtained with simple field sensors. The numerical prediction model is implemented using software based on the finite integration technique (FIT). The ESD generator is efficiently modeled, and the contact-mode discharge current is well reproduced taking into account the loading effect of the generator. Simple free-space field sensors are effectively used to measure the fields from an ESD event. Suitable numerical and theoretical characterizations of these sensors are proposed to derive a sensor transfer function that permits the fields to be reconstructed from the measured voltage. The numerical characterization is performed by Microwave Studio (MWS), while the theoretical characterization is based on lumped element circuit models of the sensors. The validation of both the proposed procedures indicates good accuracy up to 2 GHz as required by the International Electrotechnical Commission standard for ESD measurements.

EMI Susceptibility Model of Signal Conditioning Circuits Based on Operational Amplifiers

Abstract: Circuits based on operational amplifiers (OPAMPs) are susceptible to electromagnetic interference (EMI) in the radio-frequency range due to the AM demodulation produced by non-linearity of internal transistors. Such a phenomenon produces demodulated signals in the low-frequency range. This paper presents a model to predict the susceptibility of analog signal-conditioning circuits, based on a few test parameters, while ignoring the internal structure of OPAMPs involved in the circuit. The method has been experimentally tested in two applications: (1) test of simple instrumentation adapter circuits and (2) predictions of susceptibility of an amplifier for an electret microphone, tested according to EN55020.

Efficient Evaluation of the Terminal Response of a Twisted-Wire Pair Excited by a Plane-Wave Electromagnetic Field

Abstract: Twisted-wire pair (TWP) loops are used as one of the primary communication channels in digital subscriber line (DSL) networks. As part of the development of channel noise models, a transmission-line-based model for predicting the terminal response of a single TWP to an illuminating plane-wave electromagnetic field is presented. Closed-form analytic approximations of the terminal response valid for an arbitrary direction of incidence and polarization of the incoming plane-wave field are provided. A worst-case model with the very same purpose has been previously proposed in the DSL literature; however, a worst-case approach only provides partial information about the field coupling mechanism. The goal of the presented transmission-line model is to introduce a more robust yet efficient approach for characterizing radio noise interference in DSL systems. Computed results for two TWP configurations of interest are presented together with measured results for one of them.

Evaluation of Radiated EMI in 42-V Vehicle Electrical Systems by FDTD Simulation

Abstract: In this paper, a full 3-D numerical scheme based on the finite-difference time-domain method is used to predict the electromagnetic (EM) radiated interference generated by 42-V vehicle power electronic driven electrical loads. An experimental setup has been arranged in order to validate the proposed simulation tool. To this aim, the features of a semi-anechoic EM chamber have been exploited in order to operate in a shielded test site for the measurement of near-field radiated emissions. Two different 3-D geometrical configurations of realistic vehicle installations of the loads are studied. A comparative analysis among measured and computed results is performed. A good agreement between simulated and measured data is obtained. The proposed approach is suitable for the prediction of radiated EM interference generated by dc/dc converters and, particularly, by dual-voltage vehicle electric plants. In fact, due to the presence of complicated layout, the prediction of EM emissions can be a useful task in order to evaluate the EM compatibility (EMC) compliance from the design stage. Furthermore, with the growing market penetration of the ldquomore electric vehiclerdquo (MEV) concept in designing new vehicle electrical architectures, low-cost test methods for EMC assessments and suitable technical standard requirements have to be introduced. The proposed simulation tool can be usefully adopted to this aim. As an important advantage, it requires only a current measurement in the time domain. Such measurement does not need the use of a special test site or of a radiated field measurement setup.

Electromagnetic Compatibility in Power Systems (Lattarulo, F., ed.; 2007) - [Book Review]

Abstract: This 11-chapter book gives a broad summary of the electromagnetic compatibility problem that reviews physical phenomena (lightning, electromagnetic disturbances) that contribute to electromagnetic compatibility problems in buildings and transmission lines, evaluation, electromagnetic compatibility problems involving the human body, power quality assessment criteria, active rectifiers, and power filters to mitigate harmonic propagation. Each chapter begins with an introduction and is supplemented with a summary and a well-selected list of references at the end. The book is recommended for a wide audience of research and development engineers who are interested in design of modern energy and distributed power systems with special emphasis on electromagnetic compatibility problems and their mitigation. The book can also be used for advanced senior-level courses at the university level.

An EMI Resisting LIN Driver in 0.35-micron High-Voltage CMOS

Abstract: This paper describes the design of a local interconnect network (LIN) integrated output driver circuit exhibiting a high degree of immunity against conducted electromagnetic interference (EMI). The transmitted signal of this driver is shaped with a predefined slope so as to reduce electromagnetic emission at higher frequencies. The effect of EMI coupling from the data bus into the driver circuit is countered using a new feedback scheme which shields the slope shaping function from the output stage. Although the output signal may be heavily corrupted by EMI, the LIN driver continues to deliver an unaltered duty cycle, which is mandatory to obtain an error-free data transmission. Measurements show that this driver circuit manages to withstand the highest levels of the direct power injection (DPI) measurements independently of the injected EMI level.

Analysis of Electromagnetic Interference on DC Line From Parallel AC Line in Close Proximity

Abstract: As the need for electric power grows continuously, transmission systems with more delivery capability, such as HVDC lines, are also needed. However, one of the biggest obstacles to construct a new transmission system is the obtaining of sufficient right-of-way, due mainly to the economical and ecological reasons. As a consequence, ac and dc transmission lines are to be built in parallel sharing the same right-of-way. In this paper, the electromagnetic interference in a dc line, due to the capacitive and inductive coupling from a parallel ac line in close proximity, is studied in detail. A multiconductor transmission line model is elaborated in the electromagnetic transient program to calculate the induced voltage from an ac line upon a dc line. A method based on Fourier series theory, to obtain the direct current flowing into the converting transformer, is presented. The generated interferences upon the dc line are calculated and analyzed through an example regarding steady state and fault conditions. Finally, the influence of various parameters upon such interferences is discussed. The paper provides an insight on how to control the generated electromagnetic interference in the dc line on account of the induced voltage from the neighboring ac line.

New approach to EMC protection

Abstract: This paper presents new approach to EMC protection at the expense of proper use of inherent properties of coupled interconnects. The approach is based on new concept of modal filtering used jointly with known filtering principles. Some preliminary results of the approach implementation are presented. Particularly, the difference of per unit length modal delays for various types of cables and PCB interconnects is calculated. It is shown that the difference can be around 1 ns/m, while for special structures can be increased up to 5 ns/m. It allows, for example, for 1 m interconnects the modal filtration against ultra wideband pulses shorter than 1 ns and 5 ns.

Simple Analytical Models to Predict Conducted EMI Noise in a Power Electronic Converter

Abstract: Knowing the characteristics of the sources and paths involved in the injection of conducted electromagnetic interference (EMI) currents into the input source from a power converter allows one to analyze and improve a converter's electromagnetic compatibility (EMC) performance. In this paper, analytical models to predict the conducted EMI noise generated by a boost power factor correction (PFC) converter are presented. These simple models are based on the noise generation mechanism and the path through which the noise travel. The models require the measurement of high frequency characteristics of the components involved in the noise path. By comparing the predicted noise spectra with the experimentally measured noise spectra, it is verified that the proposed analytical models can be used to reasonably predict the noise generated by the PFC. The proposed models can thus be used to carry out a preliminary design of the EMI filters needed and hence their size and cost even before building and testing the power converter.

Hybrid $S$ -Parameters for Transmission Line Networks With Linear/Nonlinear Load Terminations Subject to Arbitrary Excitations

Abstract: We propose a generalized S-parameter analysis for transmission lines (TLs) with linear/nonlinear load terminations subject to arbitrary plane-wave and port excitations. S-parameters are prevalently used to model TLs such as cable bundles and interconnects on printed circuit boards (PCBs) subject to port excitations. The conventional S-parameter approach is well suited to characterize interactions among ports. However, nontraditional port excitations associated with plane-wave coupling to physical ports at TL terminals lead to forced, as well as propagating, modal waves, necessitating a modification of the standard S-parameter characterization. In this paper, we consider external plane-wave excitations, as well as port (internal) sources, and propose a hybrid S-parameter matrix for characterization of the associated microwave network and systems. A key aspect of the approach is to treat the forced waves at the ports as constant voltage sources and induced propagating modal waves as additional entries (hybrid S-parameters) in the S-parameter matrix. The resulting hybrid S-matrix and voltage sources can be subsequently exported to any circuit solver such as HSPICE and Agilent's Advanced Design System for the analysis of combined linear and nonlinear circuit terminations at ports. The proposed method is particularly suited for susceptibility analysis of cable bundles and PCBs for electromagnetic interference evaluations. It also exploits numerical techniques for structural and circuit domain characterization and allows for circuit design optimization without a need to perform any further computational electromagnetic analysis