Showing papers on "Electromagnetic compatibility published in 2005"

Electromagnetic bandgap power/ground planes for wideband suppression of ground bounce noise and radiated emission in high-speed circuits

Abstract: A power/ground planes design for efficiently eliminating the ground bounce noise (GBN) in high-speed digital circuits is proposed by using low-period coplanar electromagnetic bandgap (LPC-EBG) structure. Keeping solid for the ground plane and designing an LPC-EBG pattern on the power plane, the proposed structure omnidirectionally behaves highly efficiently in suppression of GBN (over 50 dB) within the broad-band frequency range (over 4 GHz). In addition, the proposed designs suppress radiated emission (or electromagnetic interference) caused by the GBN within the stopband. These extinctive behaviors of low radiation and broad-band suppression of the GBN is demonstrated numerically and experimentally. Good agreements are seen. The impact of the LPC-EBG power plane on the signal integrity for the signals referring to the power plane is investigated. Two possible solutions, differential signals and an embedded LPC-EBG power plane concept, are suggested and discussed to reduce the impact.

On high-frequency circuit equivalents of a vertical ground rod

Abstract: Vertical ground rods have been used extensively from the early days of electrical engineering for earth termination of electrical and lightning protection systems. They are usually represented with equivalent circuits with lumped and distributed parameters based on quasistatic approximation, which limits the upper frequency of their validity domain. However, lightning-related studies often require modeling in the megahertz frequency range. Also, emerging technologies, such as power-line communications, require analysis in frequency ranges even up to a few tens of megahertz. The rigorous electromagnetic (EM) field theory approach may be used for such frequency ranges, but equivalent circuits are needed for the usual network analysis methods. In this paper, we look at possibilities to construct simple equivalent circuits that can approximate or match results from the EM model. In particular, we compare a usual homogenous distributed parameter circuit with a nonhomogenous one determined by curve matching with results from the EM model. The analysis is illustrated using numerical simulations.

Analysis of lightning-radiated electromagnetic fields in the vicinity of lossy ground

Abstract: An antenna theory (AT) approach in the frequency domain is presented to compute electromagnetic fields radiated by a lightning return stroke. The lightning channel is modeled as a lossy-wire monopole antenna (a wire antenna with distributed resistance) energized by a current source at its base, and the ground is modeled as a lossy half-space. The method of moments is used for solving the governing electric field integral equation (EFIE) in the frequency domain. The resultant current distribution along the channel is used to calculate electromagnetic fields at different distances from the channel. All field components are evaluated using a rapid but accurate procedure based on a new approximation of Sommerfeld integrals. In contrast with the previous models, the approach proposed here is characterized by a self-consistent treatment of different field components in air or on the surface of a lossy half-space. It is shown that the omission of surface wave terms in the general field equations, as done in the perfect-ground approximation, can strongly affect model-predicted field components.

On the shielding effectiveness of enclosures

Abstract: This paper deals with new definitions of shielding effectiveness, in particular for high-frequency and transient electromagnetic fields. They are practicable and supposed to better characterize the shielding ability than the commonly used definitions. From the ratio of the time-averaged input power of the unshielded load to that one of the shielded load, in the limiting case of a vanishing load the electromagnetic shielding effectiveness is derived. This is a simple combination of the commonly used and easily measurable electric and magnetic shielding effectiveness. A similar procedure is then employed for the transient case, where in the limiting case of a vanishing load the ratio of the absorbed energies turn into the transient shielding effectiveness. Numerical results are shown for closed as well as for nonclosed cylindrical shields.

Design and modeling of high-impedance electromagnetic surfaces for switching noise suppression in power planes

Abstract: This paper presents a detailed design and modeling approach for power planes with integrated high-impedance electromagnetic surfaces (HIS). These novel power planes, which were introduced recently, have the unique ability of providing effective broadband simultaneous switching noise (SSN) mitigation. Full-wave electromagnetic simulation is used to study the impact of the geometry on the performance of these novel power planes. It is demonstrated that power planes using inductance-enhanced HIS can be designed for broadband mitigation of the SSN from the upper hundred megahertz to the gigahertz frequencies. Physics-based compact models for the unit cell of power planes with integrated HIS are developed and several of them connected in a two-dimensional array to build full models for large and multilayer power planes. The compact model offers fast analysis of power planes. As an example, we show that the full-wave simulation time of a 10/spl times/10 cm power plane with integrated HIS can be dramatically reduced from 24 to 48 h using a commercially available three-dimensional full-wave solver to less than 1 min when using the compact circuit model developed here.

Far-field-current relationship based on the TL model for lightning return strokes to elevated strike objects

Abstract: New general expressions relating lightning return stroke currents and far radiated electric and magnetic fields are proposed, taking into account the effect of an elevated strike object, whose presence is included as an extension to the transmission line (TL) model. Specific equations are derived for the case of tall and electrically short objects. The derived expressions show that, for tall structures (when the round-trip propagation time from top to bottom within the tower is greater than the current zero-to-peak risetime), the far field is enhanced through a factor with respect to an ideal return stroke initiated at ground level. The enhancement factor can be expressed in terms of the return stroke wavefront speed v, the speed of light in vacuum c, and the current reflection coefficient at the top of the elevated strike object. For typically negative values of this top reflection coefficient, lightning strikes to tall towers result in a significant enhancement of the far electromagnetic field. Expressions relating the far electromagnetic field and the return stroke current are also presented for electrically short towers and for very long return stroke current wavefronts. For the case of return strokes initiated at ground level (h=0), these expressions represent a generalization of the classical TL model, in which the reflections at the ground are now taken into account. We describe also simultaneous measurements of return stroke current and its associated electric and magnetic fields at two distances related with lightning strikes to the 553-m-high Toronto Canadian National (CN) Tower performed during 2000 and 2001. The derived expressions for tall strike objects are tested versus obtained sets of simultaneously measured currents and fields associated with lightning strikes to the CN Tower, and a reasonable agreement is found. Additionally, it is shown that the peak of the electromagnetic field radiated by a lightning strike to a 553-m-high structure is relatively insensitive to the value of the return stroke velocity, in contrast to the lightning strikes to ground.

Lightning induced disturbances in buried cables - part II: experiment and model validation

Abstract: This paper presents experimental results obtained at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida during the summers of 2002 and 2003. Currents induced by triggered and natural lightning events were measured at the terminations of a buried power cable, in the cable shield, and in the inner cable conductor. Measurements of the horizontal component of the magnetic field above the ground surface for both natural and triggered lightning are also presented. For distant natural lightning events, locations of ground strike points were determined using the U.S. National Lightning Detection Network (NLDN). Based on the theoretical developments presented in Part I of this paper , the field-to-buried cable coupling equations are solved in both the time domain and in the frequency domain. The obtained experimental results are then used to validate the numerical simulations provided by the relevant developed codes.

EMI noise control methods suitable for electric vehicle drive systems

Abstract: Methods to control electromagnetic interference (EMI) noises, especially common mode currents and radiations that are generated in electric vehicle (EV) drive systems, were studied using an electric vehicle (EV) prototype. Fast fourier transform (FFT) analyses of the voltage and current appearing in the EV drive systems showed that electromagnetic interference (EMI) noise sources are produced by voltage fluctuations occurring at the time of switching operations and the produced noise sources cause common mode currents to flow into the ground when the body frame is connected to the ground. Moreover, the flowing common mode currents induce radiated EMI noises, while the generated EMI noises are transmitted between the inverter, batteries, and motors. Thus, the produced radiated EMI noises have an effect on nearby vehicles. A method was proposed that controls common mode currents produced in EV drive systems so as to prevent a series resonance phenomenon from occurring in common current paths formed in EV drive systems. This method is also effective in controlling radiated EMI noises. Furthermore, to control radiated EMI noises, another method was proposed that cancels the surface currents flowing in P and N power transmission lines between the inverter and batteries. Effectiveness of these proposed EMI noise control methods was verified from simulations and experiments.

Graphical analysis of the spectra of EMI sources in power electronics

Abstract: A new method of analysis is proposed to graphically predict the spectrum envelope of electromagnetic interference (EMI) emitted by power electronics equipment. Relationships between the time-domain (waveforms) and the frequency-domain (spectrum) of some typical EMI signals observed in power converters are pointed out. Special attention is paid to the analysis of the transient functions of EMI signals. It is shown they behave as filtering or "smoothing" functions in the high-frequency part of the spectrum.

Power generation circuit using electromagnetic wave

Abstract: A power generation circuit using an electromagnetic wave which does not require any additional energy is provided. Power generation is performed by utilizing the electromagnetic wave existing in a space for living.

Custom spectral shaping for EMI reduction in high-frequency inverters and ballasts

Abstract: This paper presents the use of frequency modulation (FM) as a spread spectrum technique to reduce electromagnetic interference caused by high-frequency resonant inverters and electronic ballasts. Amplitude modulation (AM) effects due to resonant tank dynamics are counteracted by the use of uniquely shaped modulating waveforms, resulting in the elimination of power spectral density (PSD) distortion and reduced peak currents. Emphasis is placed on shaping the inverter or ballast output current PSD to fit within designated FCC chimneys.

Frequency domain model of conducted EMI in electrical drives

Abstract: A harmful aspect of adjustable speed drives is the presence of large high-frequency stray currents. The most important, from the view of electromagnetic compatibility, are common-mode currents at the output and input sides of the converter. Currents at the output flow through the installation ground while those at the input flow through the grid ground. These common-mode currents can cause disturbances in other units that are connected within the same power section or placed close to the drive. This paper proposes a simulation model for a complete drive system based on the frequency domain. The model accurately reproduces the behavior of common-mode currents at any point of the system and allows the user to understand the influence of each system element on the currents. Thus, the model is useful both for designing filter structures and placing them at the proper position inside the adjustable speed drive. The model is validated by means of experimental results on a 5 kVA adjustable speed drive.

A WLAN-used helical antenna fully integrated with the PCMCIA carrier

Abstract: The invention presented here is to embed the helical antenna inside an ejector of a Personal Computer Memory Card International Association (PCMCIA) carrier. The detail dimension of this antenna has been well designed to operate at the frequency 2.45 GHz, which is employed for the wireless LAN application. A low-cost electromagnetic simulation package-WIPL-D, is used to simulate this complex electromagnetic environment where the carrier metal is modeled as well, in addition to the helical antenna itself. Measurements both of return loss and radiation patterns are made too to have a comparison with the results of simulation and to prove the design thoughts given by this paper. As a final evaluation, a PCMCIA carrier with the present design is installed into a Tablet PC to have a complete measurement.

Medium voltage overhead power-line broadband communications; transmission capacity and electromagnetic interference

Abstract: A channel model suitable for multi-wire overhead medium-voltage lines is proposed This model is then employed in order to evaluate the multipath channel impulse response and the associated transmission capacity limit in actual overhead medium-voltage power distribution networks for broadband power-line communications applications Electromagnetic interference limitations of such systems are discussed

EMI energy harvester

Abstract: An energy harvester and method for electrical energy harvesting from electromagnetic interference, generated by electrical wiring and/or an electrical appliance, by receiving electromagnetic field energy radiated by the electromagnetic interference and converting the electromagnetic field energy to an electrical current for powering an electrical device. The voltage associated with the electrical current may be increased in preparation for powering the electrical device. The electrical current may be stored in preparation for powering the electrical device.

Characterization and modeling of parasitic emission in deep submicron CMOS

Abstract: This paper presents a study of the parasitic emissions of a 0.18-/spl mu/m CMOS experimental integrated circuit (IC) and an accurate method for modeling the internal current switching to forecast electromagnetic interference (EMI). The effectiveness of emission reduction techniques is quantified through a set of conducted noise measurements. A simple core model is developed, based on the current switching activity. Added to a lumped-element model of the test board and the package, good agreement between simulation and measurements are obtained up to 10 GHz. The simulation methodology may be applied to forecast the impact of low emission design techniques on the EMI of ICs.

Simulating Electromagnetic Interactions in High Power Density Inverters

Abstract: In high power density inverters with integrated functions like filters and control electronics electromagnetic interaction between components becomes an important issue. Especially filters for electromagnetic interference are very sensitive to electromagnetic fields and therefore critical to design. Nevertheless only few guidelines for optimizing placement of filter components were published up to now. This paper introduces a simulation method for predicting stray fields of components and conducting structures, which is verified experimentally for different passive components and setups. The examples demonstrate a possibility of handling interaction problems

The feature selective validation (FSV) method

Abstract: The feature selective validation (FSV) method is one of the candidate techniques for the quantitative validation of computational electromagnetics (CEM), particularly within electromagnetic compatibility (EMC) and signal integrity (SI). In applications so far, it has demonstrated significant promise and is likely to be a central feature of the growing research interest in CEM validation. This paper presents a detailed review of the FSV method and implementation. It concludes with a discussion of some of the current research topics.

Implantable cardiac pacemaker electromagnetic compatibility testing in a novel security system Simulator

Abstract: This work describes a novel simulator to perform electromagnetic compatibility (EMC) tests for active implantable medical devices (AIMDs) with electromagnetic fields emitted by security systems. The security system simulator was developed in response to over 100 incident reports over 17 years related to the interference of AIMD's with security systems and the lack of a standardized test method. The simulator was evaluated regarding field homogeneity, signal distortion, and maximum magnetic field strength levels. Small three-axis probes and a three-axis scanning system were designed to determine the spatial and temporal characteristics of the fields emitted by 12 different types of walk through metal detectors (WTMDs). Tests were performed on four implanted pacemakers with a saline phantom and correlated to a newly developed test method performed "in air" (without the phantom). Comparison of the simulator thresholds with tests performed in real WTMDs showed that the simulator is able to mimic the pacemaker interference. The interference thresholds found in the simulator indicate that pulsed magnetic fields are more likely to cause interference in pacemakers than sinusoidal fields. The security system simulator will help biomedical engineers, manufacturers of medical devices, and manufacturers of security systems to identify incompatible combinations of WTMDs and AIMDs early in the development stage.

Electromagnetic Interference in Distributed Outdoor Electrical Systems, with an Emphasis on Lightning Interaction with Electrified Railway Network

Abstract: This thesis deals with the electromagnetic compatibility (EMC) problems of distributed electrical networks, especially that caused by lightning to electrified railway. Lightning transients were fou ...

Comparison of safety distances based on the electromagnetic field and based on the SAR for occupational exposure of a 900-MHz base station antenna

Abstract: A comparison between the safety distances of a base station antenna using electromagnetic field and the specific absorption rate (SAR) assessment is made. The input power in the antenna is determined such that the electromagnetic fields and the SAR equal the reference levels and the basic restrictions, respectively, at a certain distance. Up to about 10 W the localized SAR delivers the largest safety distances when the electric field averaged in a volume is considered. This means that from 10 W and up the SAR does not need to be determined to obtain the largest safety distances. Safety distances based on the SAR will be smaller than those obtained from the electromagnetic fields when the maximum field value in a plane is considered.

Time-domain modeling of electromagnetic wave interaction with thin-wires using TLM

Abstract: A method for the time-domain simulation of electromagnetic (EM) wave interaction with thin-wires is developed. The technique is based on the standard transmission-line modeling (TLM) technique augmented with systems derived from the telegrapher's equations to represent the propagation of currents in wires. Full details of the numerical algorithms are given and examples are shown to illustrate the application of the technique to typical electromagnetic compatibility (EMC) problems.

Radiated susceptibility on the printed-circuit-board level: simulation and measurement

Abstract: The electromagnetic field coupling into the traces on a printed circuit board (PCB) is investigated. Based on a simplified equivalent-wire model, a practical simulation method is presented, which enables an efficient treatment by the method of moment, with minimum computational and modeling effort. Validation by analytic and measurement results shows an acceptable accuracy within the limits of quasi-TEM propagation. The gigahertz transverse electromagnetic cell is found to be a suitable means for measuring the field coupling into PCBs. To reduce additional common-mode coupling, special care has to be taken for the length of the measurement cable connected to the PCB within the cell.

Numerical analysis of the influence between large grounding grids and two-end grounded cables by the moment method coupled with circuit equations

Abstract: The influence between larger grounding grids and two-end grounded cables is a serious problem not only for the performance of the grounding grids but also for the safety and the normal operation of the cables. In this paper, a numerical method coupling the moment method with circuit equations is presented to analyze the performance of the grounding grid connected with two-end grounded coaxial-shielded cables in frequency domain. From the analyzed results by this method, the electromagnetic interference between the grounding grid and the two-end grounded coaxial-shielded cable is analyzed. Validity of the method is testified by comparing the results with those of experiments and with published ones. Both the method and the results are useful for designing safe grounding grid and for analyzing cable's electromagnetic compatibility problems.

Generation of a desired three-dimensional electromagnetic field

Abstract: The present invention relates to a method and a system for synthesizing a prescribed three-dimensional electromagnetic field based on generalized phase contrast imaging. Such a method and apparatus may be utilized in advanced optical micro and nano-manipulation, such as by provision of a multiple-beam optical tweezer.

High frequency modeling of bearing currents and shaft voltage on electrical motors

Abstract: The paper proposes a general method to investigate the common mode high frequency current components flowing through electrical motors supplied by electronic converters, especially focusing on bearing currents. An innovative model is defined able to address a wide frequency range (50 kHz/3 MHz) for EMI/EMC issues. By connecting the obtained model with an appropriate model of the whole electric drive, prediction of HF phenomena occurring at the addressed frequency becomes possible using a standard simulator such as Spice. A detailed analysis on a standard 3.5 kW induction motor is carried out and simulation and experimental results are presented

Shielding effectiveness of concrete buildings

Abstract: The prediction of the shielding effectiveness of concrete structures is a fundamental aspect of the architectural design phase of purpose built control centres. These buildings designed with a functional requirement to house sensitive control equipment; malfunction of such equipment may lead to loss of life and impact on revenue service. In this paper, a simple analytical approach is proposed to influence the design of buildings such that the structure provides adequate attenuation to hostile electromagnetic ambient and potential electromagnetic pulses. Comparison with numerical methods is provided. The effect of moisture content on the shielding effectiveness of a concrete wall is outlined.

Electric-Field Distribution Estimation in a Train Carriage due to Cellular Radios in order to Assess the Implantable Cardiac Pacemaker EMI in Semi-Echoic Environments

Abstract: The electromagnetic field (EMF) distributions created inside a train carriage by the cellular radios of the passengers are analyzed and the impact their electromagnetic interference (EMI) on the implantable cardiac pacemakers is evaluated based upon the analysis results. Both computer simulations and experiments using 800 MHz and 2 GHz transmitters in an actual train carriage confirm that excessively high EMF, high enough to affect the normal functions of the pacemaker, does not occur inside the carriage provided the safe distance of 22 cm specified for pacemaker users is kept. A simplified histogram estimation method for electric field strength is newly developed to deal with the complicated EMF distributions. It allows the EMI risk to pacemakers by cellular radio transmission to be quantitatively evaluated. Methodologies are described first. Typical results of FDTD analysis and actual measurement data are then shown. Finally, considerations and conclusions are made.