Showing papers on "Electromagnetic compatibility published in 2001"

Transient response of a tall object to lightning

Abstract: Experimental data showing the transient behavior of tall objects struck by lightning are reviewed. The influence of this transient behavior, illustrated by simple calculations, on measured lightning current and measured remote electromagnetic fields is discussed. The estimated equivalent impedance of the lightning channel at the time of the initial current peak is appreciably higher than the characteristic impedance of an ordinary tall object (a factor of 3 or so for both the Ostankino and Peissenberg towers and about a factor of 2 for the CN tower). The grounding impedance of a tower is typically lower than its characteristic impedance. Thus, the current reflection coefficient is negative at the top and positive at the bottom of the tower. The similarity of the statistical distributions of subsequent-return-stroke peak currents in: 1) natural downward lightning; 2) natural upward (object-initiated) lightning; and 3) rocket-triggered lightning measured at objects with heights ranging from 4.5 to 540 m suggests that current peaks are not significantly influenced by the presence of a tall object, provided that measurements are taken at the top of the object. This inference is consistent with modeling results of Melander (1984) who showed that the current peaks measured in Switzerland and Italy at the top of 70-m and 40-m towers, respectively, are essentially unaffected by the presence of the towers. If lightning current could be represented by an ideal current source, current at the top of the object would be equal to the source current at all times. The peak current measured at the bottom of a tall object is usually more strongly influenced by the transient process in the object than the peak current at the top. For example, peak currents measured in the lower part of the 540-m Ostankino tower are about a factor of two higher than the peak currents measured near the tower top because the current reflection coefficient at the bottom of the tower is near +1. Observations and modeling suggest that a tall metallic strike object replacing the lower part of lightning channel serves to enhance the lightning-radiated electromagnetic fields relative to the fields due to similar lightning discharges attached directly to ground, this effect being more pronounced for the sharper lightning current pulses.

Electromagnetic environmental impact of power electronics equipment

Abstract: A dramatic increase in the number of line-powered electronic equipment (computers and other office equipment, electronic ballasts, variable-speed drives, and consumer electronics, e.g., color televisions) has taken place. These items of equipment draw distorted, and often fluctuating, line current; they also generate high-frequency conducted and radiated noise due to the sharp edges of the waveforms characteristic of the switching power processors employed in them. As a result of the finite grid impedance, the distorted line current increases the distribution losses and causes voltage distortion; also, the fluctuation leads to visible flicker of the emitted light of lamps. The conducted and radiated high-frequency noise interferes with radio and TV reception, communication via cellular telephones, and data transmission. The result is a gradually deteriorating electromagnetic environment. This paper presents the mechanisms that generate low-frequency and high-frequency electrical noise, lists the problems caused by the various noise types, provides an overview of the standards that establish noise limits, discusses and evaluates the various mitigation techniques, and raises concerns regarding the impact of the circuitry that has to be added to the equipment to meet the harmonic limits and the pitfalls and deficiencies of the line-harmonics regulation standards.

Parasitic modes on printed circuit boards and their effects on EMC and signal integrity

Abstract: In this paper, parasitic modes, such as slotline, parallel plane, and surface wave (SW) modes, commonly found on printed circuit boards (PCBs) are analyzed and their effects on electromagnetic compatibility (EMC) and signal integrity are discussed. The analysis is based on numerical simulations using the finite difference time domain (FDTD) method which is shown to be very well suited for rigorous modeling of parasitic mode effects. The EMC and signal integrity problems discussed include power loss, crosstalk, ground bounce, and free space radiation. Design guidelines for improved EMC and signal integrity are derived from the results obtained. Comprehensive simulation and characterization of SWs using FDTD is presented for the first time.

High-frequency electromagnetic field coupling to long terminated lines

Abstract: We present a theory for the EMC problem of electromagnetic field coupling to a long line with arbitrary terminations The theory is applicable for the high-frequency plane wave electromagnetic field excitations, when the transmission line approximation is no longer valid Analytical expressions are derived for the induced current along the line, and at the two-line terminals The coefficients of these expressions are determined using a procedure based on the exact solutions of the integral equation for two similar line configurations, but having a significantly shorter length The method is, therefore, particularly efficient when considering the electromagnetic field coupling to very long lines The advantage of the proposed approach is that, in contrast with transmission line approximation, it takes into account high-frequency radiation effects Furthermore, it allows a considerable reduction in computation time and storage requirements with respect to conventional numerical solutions based on the thin-wire approximation

Model of the electromagnetic fields inside a cuboidal enclosure populated with conducting planes or printed circuit boards

Abstract: We examine the extension of a simple and versatile model of the electromagnetic fields in an equipment enclosure with an aperture to include the effects of loading the enclosure with conducting planes or printed circuit board structures (PCB). Modeling results are compared with experimental measurements of the shielding effectiveness in a cuboidal enclosure loaded with both grounded and ungrounded conducting planes and/or PCBs with a range of grounded and ungrounded tracks. Measurement results are compared with full electromagnetic simulations and the simple model to demonstrate the accuracy and range of validity of the simple model.

Underground electromagnetic fields generated by the return strokes of lightning flashes

Abstract: In this paper, equations are developed in the time domain to represent lightning generated electromagnetic (EM) fields at different depths below the ground surface. The equations connect underground EM fields to surface fields that can easily be measured or calculated. Numerous examples are given to illustrate how the signature of the electric and magnetic field vary as a function of depth as well as conductivity.

Electromagnetic energy propagation in power electronic converters: toward future electromagnetic integration

Abstract: Historically, it came about that the analysis and design of the power electronic converter center around currents and voltages in the circuits. During the last decade, the electromagnetic character of power electronic converters became more important due to the noise that the switches generate, and electromagnetic interference (EMI) and electromagnetic compatibility (EMC) standards have been put in place to control the electromagnetic noise levels. In this contribution, it is argued that coming to grips with the electromagnetic operation of switch-mode power conversion presents a barrier of knowledge that will have to be crossed in order to achieve future meaningful innovation in switch-mode power conversion. Rigorous electromagnetic analysis using realistic parameters are used to indicate important issues relating fundamental limits and technological paths for future generations of power electronic converters. Electromagnetic integration in three dimensions creates new possibilities to increase power densities.

Engineering Electromagnetic Compatibility: Principles, Measurements, Technologies, and Computer Models

Abstract: Preface to First Edition. Preface to Second Edition. Introduction. Natural and Nuclear Sources of EMI. EMI From Apparatus and Circuits. Probabilistic and Statistical Physical Models. Open--Area Test Sites. Radiated Interference Measurements. Conducted Interference Measurements. Pulsed Interference Immunity. Grounding, Shielding, and Bonding. EMI Filters. Cables, Connectors, and Components. Frequency Assignment and Spectrum Conservation. EMC Computer Modeling and Simulation. Signal Integrity. EMC Standards. Selected Bibliography. Appendix 1: EMC Terminology. Appendix 2: EMI/EMC Units. Appendix 3: Books On Related Topics. Appendix 4: EMI/EMC Standards. Appendix 5: EMC e--Resources. Index. About The Author.

Power electronic converter EMC analysis through state variable approach techniques

Abstract: A technique based on the state vector approach and a simple switch device model is proposed for electromagnetic compatibility (EMC) analysis in converter design. The conducted noise spectrum is straightforward computed in the frequency domain for hard switching converters with alternating or direct current input sources. The results are compared with PSpice time-domain simulations mixed with the fast Fourier transform, considering a buck converter. The technique proposed in this paper is appropriate for applications where calculation speed is preferred rather than high precision.

UWB and EMP susceptibility of modern electronics

Abstract: The susceptibility of different types of single microcontrollers and complex microprocessor-boards to unipolar fast rise time pulses is determined. Rise times down to 100 ps and field amplitudes up to 50 kV/m have been applied to the devices.

Conducted EMI in PWM inverter for household electric appliance

Abstract: This paper presents the mitigation effort of the conducted electromagnetic interference (EMI) in the pulsewidth-modulation (PWM) inverter for household electric appliances. First, noise sources in the PWM inverter are investigated to get an understanding of their characteristics, and the propagation of the conducted EMI is described. Next, input filters are added to: suppress it. With changing filter stages, the conducted EMI spectra are measured to identify their effect. The common-mode EMI spectrum is extracted to separate the effect of the common-mode filter and to identify the dominant noise source. A new active common-mode EMI filter is proposed to give better attenuation of the common-mode noise and to enhance the performance of additional passive filters. An efficient way to design of input filter is discussed based on the measurement results.

Electromagnetic interference in medical devices: Health Canada's past and current perspectives and activities

Abstract: Electromagnetic interference (EMI) from radiofrequency sources may cause a variety of medical devices to malfunction, compromising patient safety. An overview of Health Canada's efforts to ensure that medical devices are safe from EMI is presented. Health Canada has identified and assessed the following EMI issues: interference from wireless local area network systems, electronic article surveillance systems, metal detectors, and Bluetooth technology. Health Canada is assessing the susceptibility of medical devices to EMI from these sources to develop suitable electromagnetic compatibility requirements and other solutions to minimize risk to patients.

Experimental equivalent-circuit modeling of SMD inductors for printed circuit applications

Abstract: An understanding of the high-frequency parasitic and packaging effects of passive surface-mounted devices (SMDs) can be gained from equivalent-circuit characterization of the device. We develop a circuit model which accurately characterizes the nonideal behavior of SMD inductors mounted on a printed circuit board (PCB), considering the device packaging and the interaction between board layout and component parasitics. The model is valid over a wide frequency band up to the first resonance of the inductor. The equivalent-circuit parameters are extracted in closed form from an accurate measurement of the S-parameters of the board-mounted SMD inductor, without the necessity for cumbersome optimization procedures normally followed in RF circuit synthesis. This procedure of measuring the component in its designed PCB environment is referred to as extrinsic characterization, in contrast to the conventional intrinsic characterization employed in RF bridges and LCR meters, which does not include the board layout effects. The developed closed-form model can be directly incorporated in commercial CAD packages, and thus, it simplifies the analysis of electromagnetic field behavior in PCBs, such as prediction of radiated emissions, signal integrity, and EMI.

Wireless interface for electronic devices located in enclosed spaces

Abstract: A wireless communication system for transmitting and receiving radio frequency (RF) signals inside an enclosure such as a hull of a torpedo, autonomous underwater vehicle, or aircraft, an automotive body, or a test equipment enclosure. The wireless communication system employs low power, low frequency, spread spectrum signals to reduce multi-path transmission and reception problems inside the enclosure. The wireless communication system includes first and second electronic devices located in the enclosure. A first transmitter/receiver is connected to the first electronic device. The first transmitter/receiver transmits spread spectrum signals generated by the first electronic device and receives spread spectrum signals. A second transmitter/receiver is connected to the second electronic device. The second transmitter/receiver transmits spread spectrum signals generated by the second electronic device and receives spread spectrum signals. The first and second transmitter/receivers operate above a thermal noise threshold of the first and second transmitter/receivers and below electromagnetic compatibility (EMC) and electromagnetic interference (EMI) standards. If the enclosure includes walls which separate the enclosure into multiple sections and the enclosure is metallic, apertures filled with a dielectric material and a dipole penetrator antenna can be employed to reduce attenuation.

Design expressions for the trace-to-edge common-mode inductance of a printed circuit board

Abstract: The parasitic ground-plane inductance is responsible for common-mode radiation, as one of the major unwanted radiation mechanisms of printed circuit boards. For the computation of the common-mode inductance simple relations are known for the case that the trace is centered above the ground plane. In this paper the increase of the ground-plane inductance for arbitrary trace-to-edge distances is studied. From the exact analytical result obtained by complex analysis a much simpler real-valued relation is derived which allows one to set up dimensioning equations for the minimum distance of the trace to the board edge. The inductance increase correlates quite well with published measurement data for the common-mode current increase. A parameter study for different dimensions of the board provides a quantification of the potential electromagnetic interference (EMI) level.

An accurate Induction motor high frequency model for electromagnetic compatibility analysis

Abstract: In this paper, an accurate high-frequency model of induction motor is presented. The proposed model allows analyzation at the same time both the high-frequency phenomena up to some megahertz due to the static supply and the low-frequency phenomena usually analyzed by means of the dq motor model. The high-frequency model has been obtained by means of a frequency and time domain analysis and has been verified on a wide spread of induction motors starting from 4 up to 55 kW. The proposed model can be used to evaluate the high-frequency leakage currents, which are the cause of electromagnetic interference to electronic and electric equipment.

Integrated EMC shield for integrated circuits and multiple chip modules

Abstract: A semiconductor package has a die connected to a substrate with a transfer molding applied over the die. The transfer molding includes an electrically conductive material for forming an electromagnetic compatibility shield as an integral part thereof.

Current control technique for improving EMC in power converters

Abstract: A chaotically modulated OFF-time current mode control for DC-DC converters which spreads the inductor current spectrum is presented. Comparison with other methods proposed in the literature shows that this new technique is more suitable for reduction of inductor current spikes and therefore improves electromagnetic compatibility.

Electrical fast-transient test: conducted and radiated disturbance determination by a complete source modeling

Abstract: Tests against electrical fast transient/burst (EFT) represent a serious threat for modern high-speed electronics: besides the conducted injection of high amplitude pulse, a strong radiated field is produced during this test. The prediction of the effects of this test during the equipment early design stage requires the equivalent circuit of the generator: the output waveform into a resistive 50-/spl Omega/ load is not sufficient to recover the complete circuit, including inductive component and parasitic elements. These are essential to predict the disturbance produced in arbitrary loads, as the equipment under test can be viewed. This paper describes how to characterize the EFT generator by means of the measurement of the output voltage and current produced in presence of known loads; moreover, a procedure to calculate the current on the equipment power cord is shown, based on the use of a circuit simulator (PSPICE). Finally, the disturbance produced on different loads and the radiated field during the test are calculated and experimentally validated.

Line-pantograph EMI in railway systems

Abstract: At present, the EN50121 standards are the main reference for electromagnetic compatibility in European railway systems. These standards should improve as technology and testing develops. Therefore, major sources of EMI in a railway environment need to be better understood. This study is complex because many different railway power systems exist in Europe (1.5 kV DC, 3 kV DC, 15 kV 16.7 Hz, 25 kV 50 Hz). European railways are using new control and communication systems, and electromagnetic compatibility problems should be carefully studied and solved.

A comprehensive analysis and design of a single phase active power filter with unified constant-frequency integration control

Abstract: In this paper, an analysis and design for a single-phase active power filter (APF) with unified constant-frequency integration (UCI) control method is presented. The proposed control method eliminates the need of sensing the load current, a nontrivial task of calculating the harmonics and reactive current components, as well as the use of multipliers, as reported by many previous reported control methods. In addition, the switching loss is reduced by employing unipolar operation mode. The design methodology including electromagnetic interference (EMI) filter is also discussed in detail. The theoretical analysis is verified by experiments.

System, method, and apparatus for product diagnostic and evaluation testing

Abstract: A diagnostic method calculates a radiation intensity according to a characterization of near-field emissions of an electronic device and identifies a source or mechanism responsible for electromagnetic compatibility (EMC) or electromagnetic interference (EMI) violations. An evaluation method compares a radiation intensity to one or more emissions limits. Additional embodiments of systems, methods, and apparatus according to embodiments of the invention include obtaining spectrum content information of an electronic device.

EMC modeling and simulation on chiplevel

Abstract: Due to increasing demands for reduced electromagnetic emission on chip-level in combination with more complex circuits and faster design cycles, it is mandatory to spend effort on EMC models and simulation for chip design. In this paper, a three-level approach, based on: (1) testchip design and measurement; (2) RLC-extraction of supply system plus transistor netlist simulation; and (3) behavioural models for simple gates and complex digital modules are presented. Correlation between results of those three levels has to be established, and finally behavioural models for complete CMOS VLSI chips have to be derived and implemented in a simulation environment.

A higher-order mode transmission line model of the shielding effectiveness of enclosures with apertures

Abstract: The development of efficient phenomenological models which give accurate estimates for the coupling of electromagnetic energy through apertures and into enclosures is important for the EMC design of almost all electronic sub-systems. It has been previously shown that a simple analytical transmission line formulation gives good predictions of the shielding effectiveness of a rectangular enclosure with apertures. In this work the model is extended to include higher-order transverse electric (TE) and transverse magnetic (TM) cavity modes in the transmission line (TL) model. The loading effect of electronic components within the enclosure is modelled by the introduction of losses. The model remains very simple and computationally efficient. The finite difference time-domain (FDTD) method is used to validate the results.

A proposed set of specific standard EMC problems to help engineers evaluate EMC modeling tools

Abstract: As the complexity of high-speed electronic system packages increase, engineers and designers are required to take control of more and more aspects of electrical and mechanical engineering early in the design cycle. In order to achieve the objective of faster time-to-market and to be cost effective one needs to be able to predict the electromagnetic radiated emission noises of the system design by using full-wave simulation tools. Modifications and improvements of the design can be easily tested with simulators to reach the best possible compromise between EMC requirements and cost/thermal/etc considerations. The key contribution of this work is to provide a collection of a set of four standard problems faced by any typical system designer and example solutions from different tools by different users. The proposed standard problems include a power/ground plane decoupling problem, a printed circuit board with a microstrip trace which runs over a split in the ground reference plane, a heatsink emissions problem, and a shielding effectiveness problem. In this paper, each of these problems is described, and an example result provided.

Enhanced field simulations and measurements of the ESD calibration setup

Abstract: Simulating the complete electromagnetic field of the calibration setup for ESD testing holds two major difficulties: (A) the relevant dimensions of the setup are both very small (millimeters) and very large (meters); and (B) the time behavior of an ESD pulse is rather fast (subnanoseconds). In the first part of this paper we present new ideas to overcome these problems. The second part deals with measurements of the target current and field quantities. A new target with flat frequency responses is used in order to overcome the drawbacks of the widely used Pellegrini target which has a resonance at 3 GHz. Comparisons between measurements and simulations are also presented.

The influence of positioning tables on the results of radiated EMC measurements

Abstract: Radiated electromagnetic compatibility (EMC) tests usually apply a positioning table in the test zone of the EMC facility. The equipment under test (EUT) is positioned on this table as prescribed by EMC standards. The EMC standards implicitly assume that the influence of the table is negligible as long as such a table complies with the qualitative specification in the standard. In view of the work associated with the uncertainties of EMC standards, the influence of the positioning tables is investigated for both radiated emission and immunity testing. Measurement results and simple simulations demonstrate that the impact of a 'nonconductive table' may be significant. Requirements for positioning tables should therefore be incorporated in emission and immunity standards.

Method and apparatus for controlling electromagnetic radiation emissions from electronic enclosures

Abstract: A method and apparatus is provided for reducing electromagnetic radiation emissions. The method and apparatus of the present invention also reduce or prevent electromagnetic radiation generated by sources outside of a system assembly from interfering with and adversely affecting electrical circuits in the assembly. An electromagnetic compatibility (EMC) solution uses a lossy element, and/or an element comprised of a combination of lossy and conductive material.

Electromagnetic emissions from electrical rotating machinery

Abstract: The problem of evaluation of the electromagnetic emissions from large power electrical rotating machinery is considered. The results of three measurement campaigns are reported: emissions are correlated with the operating conditions and the characteristics of the machine under test. The measured electric and magnetic field spectra are treated so that they may be used as a reference for preliminary evaluation on similar machines.