Showing papers on "Electromagnetic compatibility published in 2008"

Electromagnetic Shielding Effectiveness of Multifunctional Metal Composite Fabrics

Abstract: The growth of the electronic industry and the widespread use of electronic equipment in communications, computations, automations, bio-medicine, space, and other purposes have led to many electromagnetic interference (EMI) problems as systems operate in close proximity. It is likely to become more severe in the future, unless proper EMI control methodology and techniques are used to meet the electromagnetic compatibility requirements. This article presents a comprehensive review of EMI shielding theory and materials. Furthermore, a method for fabricating a multifunctional metal composite fabric with electromagnetic (EM) shielding characteristics was successfully developed. The parameters influencing EM shielding properties of the metal composite fabrics were investigated. It was shown that the EM shielding effectiveness of the metal composite fabrics could be tailored by modifying the metal grid size and geometry.

High efficiency low cost safety light emitting diode illumination device

Abstract: An illumination device of high intensity light emitting diodes, produces broad illumination with high efficiency, electromagnetic compatibility, and human safety, at low manufacturing cost. Special structures of the device simultaneously provide highly efficient heat sinking, human safety protection, electromagnetic shielding, optical optimization, and 3-dimensional compatibility with traditional incandescent lamp fixtures and applications. Structures, shape, and layers of materials of the device enable industry standard safety requirements to be met.

Multilevel Converter for Traction Applications: Small-Scale Prototype Tests Results

Abstract: In ac-supplied traction systems (e.g., 15 kV, 16.7 Hz), the energy supplied by a conventional transformer results in large volume, high weight, and relatively low efficiency. In this paper, an ac-dc multilevel converter is presented that allows the use of a medium-frequency transformer in the input section of a traction drive. The proposed solution seems particularly well adapted to the different requirements (volume, weight, EMC, losses) of the electric traction domain. The system is studied from a theoretical point of view, starting from the basic module up to the entire converter structure. Simulation results and reduced-scale (10-kVA four-stage converter) experimental results are presented.

Common-Mode EMI Study and Reduction Technique for the Interleaved Multichannel PFC Converter

Abstract: Interleaved multichannel power factor correction (PFC) converter is very popular today because of its ability to reduce input and output current ripples. In this paper, the common-mode (CM) electromagnetic interference noise emission model of the multichannel PFC converter is studied. A balance technique is introduced to reduce CM noise emission. To improve the high-frequency balance, a novel topology with coupled-inductor structure is proposed. Its CM noise model is derived and balance condition for minimizing CM noise is calculated. Effects of phase shift and channel shedding on this solution are also studied. The proposed topology has effectively reduced CM noise under any phase shift and channel shedding conditions. A two-channel PFC converter is built to verify the proposed balance technique. Experimental results show that CM noise can be reduced up to 20 dB between 150 kHz and 7 MHz.

Modeling the Electromagnetic Emission of a Microcontroller Using a Single Model

Abstract: This paper presents a methodology for building an integrated circuit behavioral model that enables the prediction of its electromagnetic (EM) emissions up to several gigahertz. The model, built upon S-parameter characterization and conducted emission measurements, is used to predict the EM emissions of a commercial 16-bit microcontroller. The emission measurements are performed according to several EM compatibility standards, namely, 1 Omega /150 Omega , surface scan, and transverse EM/gigahertz transverse EM (GTEM) method, and their results show an excellent fit with model predictions.

Sensors for Applications in Magnetic Resonance Environments

Abstract: This paper analyzes sensing methods compatible with magnetic resonance imaging (MRI) and functional MRI (fMRI) reported in the literature, and presents the three generations of MR-compatible force/torque sensors we have developed for robotic systems to interact with human motion. Conventional sensors such as camera-based measurement systems, strain gauges or commercial force/torque sensors, and optical encoders may be used, if placed sufficiently away from the imaging region and equipped with adequate shielding and filtering in order to minimize electromagnetic interference caused by electric cables, the transducer, and electronics of surrounding equipment. However, electromagnetic interference can be avoided by using light transmission over optical fibers, in which case sensitive and noisy electronic components can be placed outside the MR room, and the MR compatibility issue is restricted to the used materials. Good performance can be obtained with sensing elements made from materials adapted to the location of use, combined with reflected or differential light intensity measurement over optical fibers. We have developed various force and position sensors based on this principle, ranging from MR Safe (for a definition and discussion of the terms MR Safe and MR Conditional, see Gassert , IEEE Eng. Med. Biol. Mag., pp. 12--14, May/Jun. 2008) milled polymer probes to MR Conditional assemblies combining beryllium copper blades with a polymer body, as well as smaller aluminum probes realized through a combination of milling and electric discharge machining. It appears that, in contrast to actuators, good performance is not in tradeoff with MR compatibility.

Near-Field Electromagnetic Characterization and Perturbation of Logic Circuits

Abstract: We propose here a nondestructive electromagnetic (EM) near-field test bench for both EM compatibility and susceptibility of circuits. This setup permits both the collection of the near field and injection without contact of a disturbing EM field, all through a probe. Exhaustive characterizations of probes are undertaken via simulations and experiments. According to their design, they are supposedly linked more to the electric or the magnetic field. Simulations of their EM behavior are undergone to fix their optimal geometries, leading to the best measurement performances. It is shown by both the simulations and the S-parameter measurements that their presence does not interfere with the electric behavior of the device under test. Then, logic circuits are characterized from the EM point of view, with the help of this test bench. Circuits are placed on three different printed boards: one double-sided low-frequency board without a ground plane and two single-sided boards with a ground plane and a design that is more or less optimized. EM near-field mappings highlight the strong field areas of the circuits. The need for a ground plane is highlighted. Field patterns on the traces are linked with those observed on microstrip lines. Then, an EM aggression is injected over a supposed sensitive zone of the circuit. Whichever printed board is considered, a parasitic signal superimposes itself on the output signal of the gates. Deepened studies are undergone to exhaustively explain the phenomena observed.

Susceptibility of Civilian GPS Receivers to Electromagnetic Radiation

Abstract: Civilian handheld global positioning system receivers were tested for their susceptibility against radiated electromagnetic disturbances of different characteristics and field levels. This susceptibility data were compared to the existing electromagnetic compatibility (EMC) immunity requirements for electronic devices. Some of the receivers were disrupted by continues waves at in- as well as out-of-band frequencies, at field levels far below the existing EMC requirements. The possible reason for this is discussed. In general, due to the ever-growing use of commercial-off-the-shelf equipment even for critical functions, certificates of conformity to current EMC requirements may be inadequate.

Applications of Electromagnetic Models of the Lightning Return Stroke

Abstract: Lightning return-stroke models are needed to study lightning effects on various objects and systems, as well as in characterizing the lightning electromagnetic environment. Reviewed here are models based on Maxwell's equations and referred to as electromagnetic models. In contrast to distributed-circuit and so-called engineering models, electromagnetic models of the lightning return stroke allow a self-consistent full-wave solution for both current distribution along the lightning channel and associated electromagnetic fields. In this paper, we review electromagnetic models with an emphasis on their applications.

Characterization and Modeling of the Susceptibility of Integrated Circuits to Conducted Electromagnetic Disturbances Up to 1 GHz

Abstract: This paper deals with the characterization, as well as the modeling, of the susceptibility of integrated circuits (ICs) to conducted electromagnetic disturbances such as a continuous-wave disturbance. Based on accurate measurement results, a robust mathematical model to predict the susceptibility of a CMOS inverter is developed. This model is based on a neural network approach and is validated up to 1 GHz for different test criteria. A good agreement between measurements and simulated results is reported. The mathematical model is implemented in a software tool such as Advanced Design System in order to facilitate its operation in the evaluation of the susceptibility of ICs.

Measurement and Modeling of the Magnetic Near Field Radiated by a Buck Chopper

Abstract: Static converters are used with increasingly high switching frequencies. Consequently, they impose increasingly severe electromagnetic interference(EMI) constraints in their environment. In order to study and to quantify the radiated perturbations, we have used a test bench for measuring the magnetic field radiated in the near zone. In this paper, we present measurements of the magnetic field radiated by the switching cell of a Buck chopper in the near field at high and low frequencies. By comparing the mappings of the magnetic field over the switching cell with the ones of a circular loop, we have deduced that the switching cell can be effectively modeled by a loop. The loop's geometric characteristics and its equivalent current flowing in have been determined from near magnetic field data. The model has been validated at high and low frequencies.

Use of Double Bulk Current Injection for Susceptibility Testing of Avionics

Abstract: In this paper, possible applications of double bulk current injection for susceptibility testing of spacecraft are investigated and discussed. Two test procedures are proposed: one is suitable for system-level (i.e., onboard) testing, the other for unit-level assessment of avionic equipment interconnected by multiwire shielded bundles. By enforcing equivalence between radiation and injection, both procedures are designed to inject expected electromagnetic interference (EMI) levels in the equipment under test (EUT), connected at the terminations of a wiring harness. The procedure for system-level testing requires amplitude and phase control of the radio-frequency power sources used to feed the injection probes. It allows to correlate the susceptibility effects obtained by injection with those due to a nonuniform electromagnetic field (such as the field generated by internal EMI sources in metallic enclosures). It is, therefore, suited for radiated intrasystem verifications. The procedure for unit-level testing exploits equivalence between radiation and injection in terms of the current distribution along the overshield, and applies to bundles with an arbitrary number of inner conductors. In the case of vertical polarization, this procedure allows for the reconstruction of the interference effects produced in the EUT by conventional radiated-susceptibility tests (e.g., DO-160), requiring direct radiation of the system.

Wavelet-Based Performance Evaluation of Power Converters Operating With Modulated Switching Frequency

Abstract: It has been demonstrated that modulating the switching frequency of a power converter is a valuable way for reducing the electromagnetic interference (EMI) due to the switching process. Since we are considering a signal whose frequency content varies with time, wavelets are well suited to analyze the performance of such techniques. In this paper, we evaluate the performance of spread spectrum frequency modulation (SSFM) applied to the EMI reduction of a real power converter that uses periodic pattern switching frequency modulation. The performance of the converter under investigation includes the analysis of the switching voltage spectrum (as the main source of EMI) and the output voltage ripple. This evaluation is performed with two coefficients, i.e., maximum energy ratio (MER) and energy dispersion ratio (EDR), which are figures of merit defined in this paper using time-dependent energy density distribution in frequency, obtained from the scalograms of the analyzed signals. Such figures of merit allow comparison in the time-frequency domain of different modulation techniques and the choice of the best solution for each case in terms of reduction of the peak of noise spectrum.

On-Chip Transient Detection Circuit for System-Level ESD Protection in CMOS Integrated Circuits to Meet Electromagnetic Compatibility Regulation

Abstract: A new on-chip transient detection circuit for system-level electrostatic discharge (ESD) protection is proposed. The circuit performance to detect different positive and negative fast electrical transients has been investigated by the HSPICE simulator and verified in a silicon chip. The experimental results in a 0.13-m CMOS integrated circuit (IC) have confirmed that the proposed on-chip transient detection circuit can be used to detect fast electrical transients during the system-level ESD events. The proposed transient detection circuit can be further combined with the power-on reset circuit to improve the immunity of the CMOS IC products against system-level ESD stress.

Reverberant Microwave Propagation

Abstract: : The purposes of this Reverberant Microwave Propagation work were, first, to expand measurement capabilities by an extensive investigation of short pulse excitation of empty, partially filled, and coupled cavities, and second, to improve our understanding of microwave propagation in moderately reverberant spaces, such as ship and aircraft compartments and in metal buildings. Understanding propagation in these types of spaces is increasingly important to the U.S. Navy. Various electromagnetic compatibility (EMC) issues relate to the proliferation of high-powered microwave emitters in these spaces. Also, reverberant/multipath propagation has a limiting effect on the rate at which data may be sent in digital wireless communication links.

A Metric for Evaluating the EMI Spectra of Power Converters

Abstract: The inherent switching of power devices in a switch mode power supply generates electromagnetic interference (EMI) noise. This noise is dependent on several factors such as component layout, circuit parasitics, and the control techniques implemented. Several methods have been reported in literature to mitigate the EMI problem. However, until now, a metric to characterize and compare the EMI spectra of power converters is not available in literature. This paper proposes a simple metric to measure and characterize the EMI spectrum of power converters. The proposed technique is based upon the specification and thereby the size of an external passive filter required to meet the given EMI standards. The proposed metric is useful in evaluating and comparing the severity of the EMI noise generated by different implementations of a power converter. Thus, it allows the designer to choose the better implementation option from an EMI noise perspective. The use of the proposed metric is demonstrated through the comparison of the quality of spectra of a power converter with two different switching schemes.

Analysis and modeling of conductive EMI noise of power electronics converters in electric and hybrid electric vehicles

Abstract: In developing a complex power electronic system, proper modeling at prototype sample level can save the time and cost to develop final product. Hybrid electric vehicle (HEV) is equipped with several high powered electric devices such as DC/DC converters and DC/AC inverters. Considering that there are many restrictions in mounting and wiring the electric power system in engine room, analysis and modeling of electromagnetic interference (EMI) coupling path is crucial in designing optimal electric power system satisfying various EMC regulations. In this paper, conductive common mode (CM) and differential mode (DM) equivalent models for those electric power converters used in HEV were developed and evaluated through the simulation both in time domain and frequency domain using FFT. It is confirmed that the suggested model followed the actual circuit in the point of conducted CM and DM EMI view.

Correlating the Characteristics of the CN Tower Lightning Return-Stroke Current with Those of Its Generated Electromagnetic Pulse

Abstract: Simultaneous measurements of the lightning return-stroke current derivative at the Canadian National (CN) Tower and the corresponding lightning electromagnetic pulse (LEMP) 2 km north of the tower have been performed since 1991 using broadband, high-resolution measurement systems. The recent installation of global positioning systems for time synchronization of CN Tower lightning measurement stations has enabled the correlation of the wavefront characteristics (peak, maximum derivative, and 10-90% rise time) of the return-stroke current with those of its LEMP. The characteristics of the tower's lightning electric and magnetic fields have also been correlated with each other. The current and field correlation analysis is based on August 19, 2005, CN Tower lightning return-stroke data. In addition to the strong linear correlations of the wavefront characteristics of the electric and magnetic field waveforms, an excellent linear correlation has been established between the magnetic field and current wavefront peaks. Also, a good linear correlation has been found between the magnetic field wavefront maximum derivative and that of the current. These findings are of interest in lightning detection methodology. For example, the current wavefront maximum derivative can be estimated from the detected magnetic field after taking into consideration the propagation effect on its derivative. Although weakly correlated, a general trend of increase in the magnetic field peak and maximum rate of rise has been observed as the current maximum rate of rise and peak increase, respectively. It is hoped that the field-current relationships developed in this paper, using the recent CN Tower lightning return-stroke data, will contribute to solving the inverse-source problem, one of the challenging problems in lightning research, where lightning current characteristics are estimated based on the characteristics of the measured LEMP.

Towards an EMC roadmap for Integrated Circuits

Abstract: The following document gathers a collection of information and trends about integrated circuit (IC) technology to build a tentative roadmap for ElectroMagnetic Compatibility (EMC) of ICs until year 2020, with focus on embedded system-on-chip (SoC) for automotive and consumer electronics applications.

Propagation of UWB Transients in Low-Voltage Power Installation Networks

Abstract: In this paper, the propagation of ultra-wideband (UWB) transients through different types of junctions of low-voltage power cables and one real power network of a building were investigated. For the laboratory test, it was seen that the main mode of propagation in the cables and through the junctions tested is transverse electromagnetic (TEM). The received voltage could thus be, within a small error, estimated from transmission-line theory. The main cause for decreased voltage received at the loads of the branches of the junctions is reflections due to impedance mismatch of the junctions. Large voltages can be delivered to many unprotected loads connected to the junctions. UWB transients were also injected into a residential house using a power outlet available on the outside wall of the house. It was seen that the complexity of this network creates deviation from the TEM mode. However, relatively large voltages were still received at the various outlets inside the house. It is recommended that power outlets or lamp sockets outside buildings are controlled from inside using two-pole switches that reduce the received voltage to reduce the risk of conducted intentional electromagnetic interference.

Novel Parameter Estimation of Double Exponential Pulse (EMP, UWB) by Statistical Means

Abstract: High-power electromagnetic environments, such as the high-altitude electromagnetic pulse (HEMP) and the ultrawide-band (UWB) pulses, pose dangerous threats to electronic systems. Such pulse shapes are often described physically by the characteristic parameters: the rise time tr, pulse width tfwhm and maximum electric field strength Emax, and mathematically by the double exponential function with characteristic parameters alpha, beta ,kappa . and E0. In practice, it is very necessary to transform the two groups of parameters into each other. In this paper, a novel relationship between the two groups of parameters is established by statistical means. This method utilizes only four assistant variables to realize the transform, and the overall estimation error is less than 2.0%.

Investigation of the Electromagnetic Interference Threat Posed by a Wireless Network Inside a Passenger Aircraft

Abstract: Recent years have witnessed an incisive push to allow the use of wireless networks inside passenger aircraft. Research was recently conducted to investigate the internal electromagnetic (EM) environment excited by a wireless network inside a passenger aircraft to provide quantification of the ensuing EM interference threat. An airbus A319 EM model was developed and validated using experimental data and analytical techniques. The validated model was applied to the investigation of an 800 MHz cellular network. The peak electric field strength inside each of the A319 EM models examined was much less than the most severe RTCA/DO-160D radiated susceptibility test levels. The current coupled to a cable running along the length of the fuselage was much less than the minimum operating parameters of an extremely sensitive avionic system (e.g., strain sensor). The results obtained help to quantify and reinforce the conclusion of the major research efforts that the likelihood of interference with flight critical systems is low. The model presented herein can be easily adapted to study EM propagation for various types of wireless network and aircraft configurations, and the modeling approach employed could be of potential use in modeling other large, complex structures.

A Suitable Method for Ecovehicles to Control Surge Voltage Occurring at Motor Terminals Connected to PWM Inverters and to Control Induced EMI Noise

Abstract: A method that is suitable for ecovehicles, which controls the surge voltage appearing at motor terminals that are connected to a pulsewidth modulation inverter with short leads that are less than the critical cable length (i.e., the shortest length at which full reflection may occur), is described here. Also, a method to control electromagnetic interference (EMI) noise, which is induced by the surge voltage, is discussed. Ecovehicles have the problem where insulation degradation of motors occurs due to the surge voltage being repeatedly applied to motor terminals during long lifecycles. EMI noise such as the shaft current and the radiated noise, which are induced by the generated surge voltage, easily diffuse into other electric devices due to the high-density packaging structure. The diffused EMI noise may cause a malfunction of the vehicle controller. An EMI noise controller is studied, which can meet the high-density packaging requirements for ecovehicles like electric vehicles. The EMI noise controller is attached on the motor terminals and simultaneously suppresses the surge voltage and the noise. After clarifying surge voltage characteristics and a circuit model for expressing the surge phenomenon through experiments and simulations, an EMI noise controller is proposed, which uses a multilayer printed power circuit technique. It is verified through simulations and experiments that the proposed controller has the ability to simultaneously control the surge voltage and the EMI noise, such as the radiated noise and the shaft current (the bearing current), which are induced by the surge voltage.

Emission and Susceptibility Modeling of Finite-Size Power-Ground Planes Using a Hybrid Integral Equation Method

Abstract: A novel method based on hybrid integral equation for electromagnetic emission and susceptibility modeling of power-ground planes with a finite size is proposed in this paper. First, the entire computational domain is divided into the internal subdomain including the substrate sandwiched between the power and ground planes and the external subdomain surrounding the power-ground planes. The internal subdomain is modeled by using the integral equation with dyadic Green's functions of the rectangular cavity, while the free-space Green's function is used to model the outside subdomain. These two kinds of integral equations are coupled through the equivalent electric and magnetic currents that are placed on the interfaces. The key advantage of this proposed method is its ability to model both emission and susceptibility problems. This method can accurately simulate the impedance of the power-ground planes and the radiated field. In particular, it is able to predict the induced electric currents inside the power-ground planes that result from external interference sources. Therefore, this technique is able to provide a complete solution for the electromagnetic compatibility analysis of the system-level package.

Spread spectrum in DC-DC full bridge voltage converter by a dual randomized PWM scheme

Abstract: Randomized pulse width modulation (RPWM) deals better than deterministic PWM (DPWM) with electro-magnetic compatibility (EMC) standards for conducted electromagnetic interferences (EMI). In this paper, we propose a dual RPWM scheme for full bridge DC-DC voltage converter. This scheme is based on a triangular carrier with two randomized parameters. By using directly the randomized parameters of the carrier, a mathematical model of the power spectral density (PSD) of output voltage is developed. Then, the PSD analysis shows the EMC advantage of the proposed dual randomization scheme comparatively to the classical simple randomization schemes. Finally, FFT analysis confirms this advantage.

Experimental Investigation of the Electromagnetic Interference of ZigBee Transmitters on Measurement Instruments

Abstract: This paper deals with the electromagnetic susceptibility of measurement systems when subjected to interference generated by short-range, low-power wireless transmitters. A ZigBee transmitter was used as an interfering source operating close to the instrumentation under test. The results of numerous tests prove that different kinds of measurement instrumentation can be affected by the wireless module interference. Significant metro- logical performance decay was observed for both frequency- and time-domain measurements carried out by instrumentation whose bandwidth includes the ZigBee frequency operating range.

A Chaotic Peak Current-Mode Boost Converter for EMI Reduction and Ripple Suppression

Abstract: A novel chaotic peak current-mode boost converter is proposed. By deriving its corresponding current mapping function, a thorough analysis of its chaotic behavior is carried out. As demonstrated both in simulations and experiments, the proposed design can effectively reduce electromagnetic interference and suppress ripples of the converter's output, resulting in a better design for power supplies.

The Use of Electronic Components in Railgun Projectiles

Abstract: This paper deals with experiments and calculations performed in order to investigate the influence of the electromagnetic hardening of payloads in a railgun. This is a complex task: besides the large amplitudes of the in-bore magnetic fields due to the pulsed current, the exit of the projectile from the muzzle and the consequences of plasma arcs have to be considered. At the muzzle the magnetic induction can drop from several Teslas to zero within some microseconds, leading to very high induced voltages and electric fields in the metallic parts of the projectile. On the other hand, the electric contact established by solid armatures tends to develop into electric arcs at high velocities during the launch. These plasma arcs as well as the closing switch transients of the railgun circuit are a source of electromagnetic radiation in a broad spectral range. Some electronic devices were selected and tested with static setups corresponding to the previous conditions. In a first phase a series of static railgun experiments (no projectile movement) was performed. In a second phase, static experiments simulating the muzzle exit conditions were carried out. Finally, the influence of electromagnetic waves emitted during railgun experiments on electronic devices was investigated, using a static setup with a conventional spark gap.

Winding Capacitance Cancellation forThree-Phase EMC Input Filters

Abstract: Techniques have been presented in the literature for canceling stray capacitances for inductors in single-phase power filters With the same aim, the alternatives provided by three-phase systems are explored here A thorough theoretical analysis is presented, where pros and cons of parasitic capacitance cancellation networks are highlighted and improvements are proposed A systematic mathematical procedure to evaluate impedances for different noise modes in three-phase circuits is presented The influence of parasitic effects is accessed and asymmetric capacitance cancellation is proposed, facilitating applications in switched power circuits Experimental results are shown demonstrating the effectiveness of the presented techniques in an electromagnetic compatibility filtering application