Showing papers on "Electromagnetic compatibility published in 2011"

Finite-Element Analysis of Short-Circuit Electromagnetic Force in Power Transformer

Abstract: Transient electromagnetic forces in radial and axial directions induce critical mechanical stress on windings and transformers. In this paper, short-circuit electromagnetic forces that are exerted on transformer windings are investigated. A 3-D transformer model is considered to calculate the transient electromagnetic forces. The magnetic vector potential, magnetic flux density, and electromagnetic forces due to the short-circuit transient currents applied to the power transformer are analyzed by a coupled electromechanical finite-element method. The results obtained are compared with the analytical results and show good agreement. The numerical modeling technique dealt with in this paper is expected to be useful in the design of power transformers.

Coupling of Stochastic Electromagnetic Fields to a Transmission Line in a Reverberation Chamber

Abstract: A new method for the numerical simulation of the stochastic electromagnetic environment of a mode-stirred chamber is presented in this paper. This method is based on the plane-wave integral representation for the fields and uses a Monte Carlo simulation to replace the analytical integration by numerical summation. Therefore, a field generator is implemented as a program. The numerically generated field distributions and spatial correlation functions are compared to the analytical solutions for the validation of the field generator. With this generator, the field coupling to a simple transmission-line structure can be numerically simulated. The coupled current or voltage has to be regarded as a stochastic value as well, and therefore, parameters like the mean value and the standard deviation along the line are calculated. For the special case of a matched line, an analytic solution is introduced in order to validate the numerical results. The simulation also allows for investigating the statistical distribution and correlation of the coupled current along the transmission line. Numerous simulated results are compared with measurements.

A Simple and Efficient Design Procedure for Planar Electromagnetic Bandgap Structures on Printed Circuit Boards

Abstract: In this paper, a simple synthesis procedure to design planar electromagnetic bandgap (EBG) structures is proposed. It is based on the consideration of the excess of inductance of a patterned plane with respect to a solid one. The planar EBG structure is sized from the bandgap starting and ending frequencies, and few others specifications employing a closed form formulation. The proposed method is also suitable for the design of embedded planar EBG. The procedure is validated by using measured and numerically computed results.

Study of Conducted EMI Reduction for Three-Phase Active Front-End Rectifier

Abstract: The problem of electromagnetic interference (EMI) plays an important role in the design of power electronic converters, especially for airplane electrical systems. This paper explores techniques to reduce EMI noise in three-phase active front-end rectifier. The Vienna-type rectifier is used as the object. The design approach introduced in this paper is using a high-density EMI filter to satisfy the EMI standard. Design methodology is introduced in the paper by a three-stage LC- LC-L filter structure. In particular, the cause of high noise at high frequencies is studied in experiments, and the coupling effect of the final-stage capacitor and inductors is investigated. In order to reduce the EMI noise in the mid-frequency range, the application of random pulsewidth modulation (PWM) is also presented. The performance of random PWM in a Vienna-type rectifier is verified by theoretical analysis and experimental results. The approaches discussed in this paper significantly reduce the EMI noise in the Vienna-type rectifier, and therefore, the filter size can also be reduced.

An Optimized Feedback Common Mode Active Filter for Vehicular Induction Motor Drives

Abstract: This paper proposes a common mode (CM) electromagnetic interference active filter devised for application in automotive induction motor drives. The active filter is based on a feedback scheme and it is realized using linear amplifiers. It performs the compensation of the CM voltage at the motor input, allowing an increase of the drive reliability and a reduction of the harmonic content of leakage high-frequency CM currents that affect the vehicle electromagnetic compatibility. A size-optimized layout is proposed and the influence of the power linear amplifier performance on the CM voltage compensation is discussed. General guidelines for the active filter design are given and its experimental implementation is presented. Finally, the filter performance is assessed by simulations and experimental tests.

EMI Analysis and Evaluation of an Improved ZCT Flyback Converter

Abstract: Switching power supplies are sources of noise for sensitive circuits. Converters should comply with electromagnetic compatibility (EMC) rules so that the electromagnetic interference (EMI) caused by switching cannot interfere with the normal operation of adjacent circuits and also the converter itself. The produced interference can be in the form of conduction or radiation. In this paper, some techniques are used in switching converters to suppress EMI with emphasis on the conduction form. EMI analysis and evaluation of a conventional flyback converter and a proposed zero-current transition (ZCT) flyback converter is achieved by simulation and experimental results. In addition to evaluating some EMI suppression techniques, the main objective of this paper is to improve EMI in the topology design stage. The operating modes of the improved ZCT flyback are discussed. In addition to the efficiency improvement, the amount of EMI reduction of this ZCT flyback and the effectiveness of some EMI reduction techniques are shown by practical implementation.

Imbalance Difference Model for Common-Mode Radiation From Printed Circuit Boards

Abstract: The differential-mode signals in printed circuit board (PCB) traces are unlikely to produce significant amounts of radiated emissions directly; however these signals may induce common-mode currents on attached cables, enclosures, or heat sinks that result in radiated electromagnetic (EM) interference. Full-wave EM modeling can be performed in order to determine the level of radiated emissions produced by a PCB, but this modeling is computationally demanding and does not provide the physical insight necessary to explain how differential signals induce common-mode currents on distant objects. This paper describes a model for determining the common-mode currents on cables attached to a PCB that is based on the concept of imbalance difference . The imbalance difference model is derived from research that shows that changes in geometrical imbalance cause differential- to common-mode conversion. This paper applies an imbalance difference model to PCB structures and compares the resulting equivalent source configurations to those obtained with traditional voltage- and current-driven models, as well as full-structure simulations.

Assessment of Human Body Impedance for Safety Requirements Against Contact Currents for Frequencies up to 110 MHz

Abstract: This paper deals with contact currents that may occur when the human body is in contact with two electrodes at different electrical potentials, e.g., an electrical/electronic device and the floor. Actually, any device must comply not only with electromagnetic compatibility and safety requirements, but also with specific electromagnetic field exposure recommendations in order to prevent health hazards for the occupational and general public population. Since the contact currents depend on the applied voltage and on the human body impedance, this last parameter has been measured for several configurations in a broadband frequency range, from 40 Hz to 110 MHz. From the measurement results, a new equivalent circuit of the human body impedance is derived by using a vector-fitting procedure. This equivalent circuit is very easy and can be adopted for compliance tests against contact currents.

Channel Characterization and EMC Assessment of a PLC System for Spacecraft DC Differential Power Buses

Abstract: This paper investigates the possibility of using the powerline communications (PLC) technology to transmit data along differential dc power buses employed in spacecraft. To this end, a point-to-point interconnection between the power control and distribution unit (PCDU) and a dc/dc converter is considered. The power bus is composed of a twisted-wire pair (TWP) above ground, and capacitive coupling and inductive decoupling networks are adopted. The analysis focuses on channel characterization and electromagnetic compatibility (EMC) assessment of a PLC link for low-speed interconnections with sensors. A transmission line model is adopted for the powerline (PL) involving measurement-based emission models for the power units connected to the line ends. Modal analysis is used to estimate the channel performance in terms of signal and noise transfer ratios. It is shown that use of a balanced transmission scheme assures higher performance both in terms of channel transfer function and immunity to the PL-conducted noise generated by dc/dc converters. A prototype of the PLC link, involving a specific implementation, is realized to prove feasibility and to analyze the system EMC behavior in terms of radiated emissions, conducted and radiated susceptibility.

EMC measurements in the time-domain

Abstract: In this tutorial presentation, broad-band time-domain electromagnetic interference (EMI) measurement techniques are discussed. Time-domain EMI measurement systems are based on broad-band analog-to-digital conversion and subsequent real-time digital processing of the EMI measurement signals. This allows us to reduce the measurement times by several orders of magnitude. Modern time-domain EMI measurement systems for frequency bands up to 18 GHz and their principles of operation are presented. Like conventional EMI receivers, time-domain EMI measurement systems facilitate the measurement of average-, rms, peak-, and quasi-peak values of the EMI. Additionally, time-domain electromagnetic interference measurement systems allow measuring phase-spectra, short-time spectra and to performing statistical analysis of the measured signals.

Worst-Case Induced Disturbances in Digital and Analog Interchip Interconnects by an External Electromagnetic Plane Wave—Part I: Modeling and Algorithm

Abstract: This paper deals with the susceptibility of electronic units to radiated electromagnetic (EM) interference and specifically, it focuses on the parasitic coupling of EM fields with printed circuit board interconnects like microstrip lines. To this purpose, a uniform lossless microstrip line illuminated by an EM plane wave is considered and the voltages at the line terminations are evaluated referring to the Baum-Liu-Tesche equations. Based on this, a new algorithm to identify, frequency-by-frequency, the incidence angles and the polarization of the impinging field that gives rise to the maximum induced voltages at the line terminations is presented.

Improvement of Electromagnetic Compatibility of Motor Drives Using Hybrid Chaotic Pulse Width Modulation

Abstract: This paper proposes and implements a new hybrid chaotic (HC) pulse width modulation (PWM) scheme for the reduction of electromagnetic interference (EMI) in alternating current (AC) motor drives. This scheme utilizes logistic mapping to simultaneously chaoize both the carrier frequency and the pulse position. Compared with available chaotic PWM schemes such as the chaotic-pulse-position-modulated (CPPM) PWM and the chaotic-amplitude-frequency-modulated (CAFM) PWM, the proposed scheme is a synergy of CPPM-PWM and CAFM-PWM. Thus, it possesses a hybrid characteristic, namely the peaky EMI is suppressed while the occurrence of low-order noises is reduced. Both simulation and experimental results are provided to support the validity.

Suppression of common-mode input electromagnetic interference noise in DC–DC converters using the active filtering method

Abstract: This study introduces a technique that combines passive and active electromagnetic interference (EMI) filtering methods to attenuate the common mode conducted noise in the input bus of the DC/DC converter and to minimise the size and the cost of the existing passive EMI filters. The technique presented can be implemented in all DC/DC converters topologies to provide a level of compliance with the electromagnetic directives. The circuit analysis and the attenuation curves showing the performance and the viability of this technique is provided. The filter input/output impedance criterion is verified to ensure the stability of the converter, by measuring the gain and the phase margins of the open-loop frequency response of the converter. The proposed technique provides a valuable design solution for compliance engineers where the Printed Circuit Board real-estate is an issue. Experimental results reveal more than 30 dB attenuation across the electromagnetic compatibility spectrum. This method contributes to the reduction of the size and weight of the input passive EMI filter. The proportion of the passive filter as compared to the DC/DC converter device can vary from 5 to 3%, depending on the converter specifications. Experimental results to demonstrate the performance and the effectiveness of the input active EMI filter in DC/DC converters are presented.

Experimental Study of Electromagnetic Environment in the Vicinity of High Voltage Lines

Abstract: Problem statement: Several studies have investigated the impact of electromagnetic field generated by high voltage power lines on environment. The evaluation of electric and magnetic field quantities are of paramount interest in the characterization of electromagnetic environment of the proposed line. The purpose of this study was to analyze the behavior of electromagnetic fields generated by power lines in an area of strong population. Approach: The method applied in this study was gradual; examined the effects of different couplings between the different neighboring lines on behavior of electric and magnetic fields. Later, these lines will be used as a source of disturbance applied to the auditory implants EMC. Results: The implications of experimental results were also compared and discussed with new standard. Conclusion: The maximum intensities of electric and magnetic fields measured for the circuit of three lines close to each other, within the El-HADJAR substation were significantly lower than the ICNIRP reference levels for occupational and no occupational exposures.

DC-DC converters with reduced mass for trackers at the HL-LHC

Abstract: The development at CERN of low noise DC-DC converters for the powering of front-end systems enables the implementation of efficient powering schemes for the physics experiments at the HL-LHC. Recent tests made on the ATLAS short strip tracker modules confirm the full electromagnetic compatibility of the DC-DC converter prototypes with front-end detectors. The integration of the converters in the trackers front-ends needs to address also the material budget constraints. The impact of the DC-DC converters onto the material budget of the ATLAS tracker modules is discussed and mass reduction techniques are explored, leading to a compromise between electromagnetic compatibility and mass. Low mass shield implementations and Aluminum core inductors are proposed. Also, the impact on emitted noise due to a size reduction of critical components is discussed. Finally, material reduction techniques are discussed at the board layout and manufacturing levels.

Method for testing electromagnetic compatibility (EMC) of electrically-driven automobile

Abstract: The invention provides a method for testing the electromagnetic compatibility (EMC) of an electrically-driven automobile. The electromagnetic interference of the electrically-driven automobile is different from that of the common internal combustion engine automobile, as far as the work principle of the electrically-driven automobile is concerned, the electrically-driven automobile has stronger electromagnetic disturbance property and higher anti-electromagnetic interference due to the application of a large-scale electronic system, the electrically-driven automobile is arranged on a loaded chassis dynamometer and runs on the chassis dynamometer at specific speed, the chassis dynamometer realizes energy absorption, and the electromagnetic compatibility of an automobile in a running state is evaluated from two angles of automobile electromagnetic interference (EMI) and automobile electromagnetic susceptibility (EMS), thereby when the automobile normally runs, the electromagnetic interference of the automobile can be accurately measured.

Method for Determining Whether or Not Information is Contained in Electromagnetic Disturbance Radiated From a PC Display

Abstract: To evaluate the possibility of information leakage by observing the electromagnetic disturbance radiated from a PC display, we propose an evaluation method by using a spectrum analyzer that is commonly used for electromagnetic interference measurement without reconstructing the displayed image. In this method, we measured the spectrum when the white and time-varying stripe patterns are displayed, and determined whether or not the disturbance contains the frequency component of the display pattern from the level difference. By using the patterns, we can easily evaluate the possibility of information leakage in radiated disturbance from a PC display in a wide frequency range.

Analysis and Optimization of Slotless Electromagnetic Linear Launcher for Space Use

Abstract: As the exploitation of astrospace deepens, many new types of space-based electromagnetic launchers (EMLs) have aroused wide attention and discussions. Compared with traditional slotted electromagnetic linear launchers, a slotless-plate permanent-magnet linear synchronous motor can easily meet demands such as flexible structure, light weight, and high control precision for space use. This paper analyzes the magnetic field of the slotless inverted-U structure based on the equivalent-magnetizing-current method. The validity of this technique for integral-slot configuration is confirmed with finite-element analysis. Then, the influence of the main design parameters is investigated, and design optimization guides are established for the selection of the key design parameters. To reach the suitable air-gap flux density here, some new constructional optimization details are discussed. Design optimization is also performed to fulfill enough thrust for the EML system.

Electromagnetic Characterization of Composite Materials and Microwave Absorbing Modeling

Abstract: This book chapter is based on the experimental activities conducted mainly at Sapienza University of Rome: Astronautic, Electric and Energetic Engineering Department in collaboration with University of Maryland, Institute for Research in Electronics and Applied Physics (IREAP). A branch of scientific research about composite materials is focused on electromagnetic characterization and subsequent application of electric conductive polymers. The use of such structures is relevant in aerospace/aeronautics, for electromagnetic (EM) protection from natural phenomena (lightning), and intentional interference with radar absorbing materials (RAM), in nuclear physics for shields adopted in particle accelerators, and for nuclear EM pulses (NEMP) protection, in electromagnetic compatibility (EMC) for equipment-level shielding, high-intensity radiated fields (HIRF) protection, anechoic chambers (for the realizations of wedges and pyramidal arrays), and human exposure mitigation. In this chapter, composite reinforced by carbon nanostructured materials are considered, mainly because of their interesting electromagnetic characteristics, such as high electrical conductivity and excellent microwave absorption. Composite materials as well their absorption capability are analyzed and numerical design of wide frequency band microwave absorbing structures is presented and discussed in details. It is crucial to highlight the need of interdisciplinary research fields to go through nanomaterials: besides nanotechnology, also electromagnetic wave propagation theory, composite materials manufacturing techniques, evolutionary computation algorithms, and use those to design the “quasi perfect absorber” are strongly required. In particular, we propose an inhomogeneous multilayer absorber made of micrometric graphite (at different wt%), and nanometric carbon particles (SWCNTs, MWCNTs, CNFs, at different wt%). At the end, an improvement of the traditional absorbers has been achieved upon optimization through an in-house winning particle optimization (WPO) algorithm, this last appositely conceived for absorbers optimization. Main goal of the presented work is to optimize the absorbers

Disturbance Observer-Based Control of a Dual-Output LLC Converter for Solid-State Lighting Applications

Abstract: Feedback sensor isolation is often an expensive necessity in power converters, for reasons of safety and electromagnetic compatibility. A disturbance observer-based control strategy for a dual-output resonant converter is proposed to overcome this problem. Current control of two LED loads is achieved through estimation rather than measurement. Robustness against temperature changes, which have significant impact on the behavior of the LEDs, is achieved through estimation of offsets in the forward voltages of the LED strings. The power converter and LEDs are modeled accurately to obtain a good estimation accuracy. The whole implementation is steered toward a low-cost solution.

Surge immunity test of personal computer at power lines

Abstract: This paper deals with problems arising at Electromagnetic Compatibility (EMC) in relation to the interference caused by surge voltages and currents. For this purpose, IEC 61000–4–5 Standard has been instituted, describing the procedure of testing and verification of a device for immunity against surge. Specifically, measurements and tests were performed on an investigation of surge immunity of a personal computer at power lines. Response of the testing computer under different coupling modes of the surges and different test levers were presented. The results implied that when the surges were applied between phases or the phase shifting was 90° or 270°, the tested personal computer's surge immunity was lower. The information in this paper can also be used in the lightning protection design by the computer manufacturer.

Lightning electromagnetic fields and induced voltages: Influence of channel tortuosity

Abstract: Models for calculation of lightning induced overvoltages usually assume a straight and vertical lightning channel. However, it is well known that the lightning path is tortuous on scales ranging from 1 m to 1 km. In this paper the tortuosity effect is analyzed for both lightning-generated electromagnetic fields and induced voltages. For a schematic representation of tortuous lightning channel, it is shown that at close and intermediate ranges the predominant effect is due to the inclination of the lowest channel segment; only for fields at relatively far ranges the overall tortuosity effect becomes appreciable.

Effect of Genetic Algorithm parameters on convergence of the electromagnetic inverse method

Abstract: Nowadays, the EMC researches have been advanced. The evolution, the diversity of the calculation's method and computing resources have to emphasize the investigations dedicated to the electromagnetic modeling method. Thus, we find the electromagnetic inverse method. It attracted the attention of several research's teams. This method can use different methods of optimization and, especially, the Genetic Algorithms (GA). In this work, we apply the electromagnetic inverse method coupled with the method of GA in order to model the radiated emissions of electrical circuits with the electric and magnetic dipole from near field measurement. In this paper, we study the effect of the parameters of Genetic Algorithms on the convergence of the electromagnetic inverse method. To do it, we changed the main parameters of GA in Matlab and we study the effect of each parameter.

Impedance and Emission Optimization of Low-Voltage DC Motors for EMC Compliance

Abstract: This paper presents a method to automatically generate high-frequency (HF) generic electrical models for low-voltage dc motors. A software model generator creates an electrical circuit which reproduces both HF impedance and emission spectrum of any common dc motor within a frequency range from 150 kHz to 1 GHz. The impedance and emission spectrum are calculated from construction and material parameters like armature geometry and winding wire radius only; no measurements are required. This makes it possible to perform sensitivity analyses of motor construction parameters and minimize the motor's electromagnetic interference early in its design phase before samples and measurements are available.

System simulation for EMC network analysis

Abstract: This paper uses compact models of power electronics converters to represent their EMC behavior. The model does not need any knowledge of the converter design since it is identified from external measurements. Three different DC-DC converters will be identified and the model validated in various network environment. Then, the models association in a DC network will be studied.

Quantification of Self-Damping of Power MOSFET in a Synchronous Buck Converter

Abstract: Ringing in the switching waveform of the switching power supply (e.g., synchronous buck converter) is known to cause broadband electromagnetic interference problems in the 30-300 MHz range. The measured switching waveform shows overshoot and, then, exponential decay of the ringing. It has been observed that this exponential decay rate varies significantly between using different low-side FETs; thus, the low-side FET dominates the attenuation of the ringing. This paper provides a novel method for quantifying the losses by using the measureable quantity “ Ross,” which is equivalent to the loss of the output capacitance Coss of the FET. This paper describes the method of measuring Ross and explains its relevance to the self-damping of the switch ringing. The method permits selection of a low-side FET to optimize the electromagnetic compatibility performances of the supply.

Postprocessing of Near-Field Measurement Based on Neural Networks

Abstract: This paper presents postprocessing based on neural network (NN) models to reconstruct the magnetic near-field profile with an improved spatial resolution for one or different frequencies. The models aim at decreasing the time required to perform near-field electromagnetic compatibility (EMC) measurements. The multilayer perceptron (MLP) NNs are used to determine the magnetic near field radiated by passive devices and power electronics components. An optimization method, called the split-sample method, is implemented to determine the structures of the NN. The results obtained with the proposed method are compared with the measurement results. A graphic interface (GUI) is created to simplify the utilization of the developed NN models.

Study of high-frequency electromagnetic transients radiated by electric dipoles in near-field

Abstract: The study investigates transient electromagnetic (EM) radiation in the near-field zone of a system of electric dipoles and the usage of the plane wave spectrum (PWS) concept for extraction of a 3-D field from 2-D measurements. Both aspects are important in the modelling and characterisation of radiated emissions in electromagnetic compatibility applications, which are extended here to time domain. Analytical expressions for a set of dipoles excited by short-duration Gaussian pulses, which in the author's approach are used to model EM radiation, are presented and implemented into a Matlab program to calculate the time-dependent distributions of the three electric field components Ex(t), Ey(t), Ez(t). These results are then used to verify the new technique of extraction of the time-domain component Ez(t) of the electric field from measurements of the two other components, Ex(t) and Ey(t). The details of the technique, based on PWS method applied to the time domain, are presented. Very good agreement between the extracted and analytically calculated fields has been achieved. Further verification and comparison has been done by the simulation in the time domain of the system of dipoles using commercial 3-D EM software.