Showing papers on "Electromagnetic compatibility published in 2006"

Optimal Design of a Hybrid Winding Structure for Planar Contactless Battery Charging Platform

Abstract: Planar contactless battery charging platform is an emerging technology that has the potential of unifying the charging protocols of portable consumer electronic products. In this paper, a new hybrid structure which consists of a coil and a spiral winding is proposed for improving the uniform magnetic field distribution over the charging surface. An analysis into an optimal design of the number of turns and the dimension of the spiral winding is presented for a given concentrated coil. The uniform magnetic field distribution of the designed prototype is measured by an electromagnetic compatibility scanner and by an energy-receiving coil. Based on circuit modeling and analysis, the inverter circuit topology and particularly the resonant compensation tank is designed for maximizing power transfer for multiload applications. A design procedure is proposed and verified by the experiments. An efficiency of about 80% has been achieved for the coupled structures when four loads are charged on the platform simultaneously.

Electromagnetic Compatibility of Integrated Circuits: Techniques for low emission and susceptibility

Abstract: Electromagnetic Compatibility of Integrated Circuits: Techniques for Low Emission and Susceptibility focuseson the electromagnetic compatibility of integrated circuits. The basic concepts, theory, and an extensive historical review of integrated circuit emission and susceptibility are provided. Standardized measurement methods are detailed through various case studies. EMC models for the core, I/Os, supply network, and packaging are described with applications to conducted switching noise, signal integrity, near-field and radiated noise. Case studies from different companies and research laboratories are presented with in-depth descriptions of the ICs, test set-ups, and comparisons between measurements and simulations. Specific guidelines for achieving low emission and susceptibility derived from the experience of EMC experts are presented.

Reduced Conductive EMI in Switched-Mode DC–DC Power Converters Without EMI Filters: PWM Versus Randomized PWM

Abstract: This paper addresses improved electromagnetic compatibility (EMC) in switched-mode power converters (SMPCs), without using electromagnetic interference (EMI) filters. A practical solution is proposed for minimizing conductive EMI in a pulsewidth modulated (PWM), and random PWM dc-dc power converters. A comparative investigation is performed into the use of different random modulation schemes (driven by the DSP-2 board with the TMS320C32) as against the normal PWM. The effectiveness of randomization on spreading those dominating frequencies that normally exist in constant frequency PWM schemes is evaluated by power spectral density (PSD) estimations in the low-frequency range. Some parasitical- and topology-based EMI sources in devices are presented and frequency analysis is shown by using the discrete Fourier transform (DFT). SPICE simulations are also used to verify practical solutions for eliminating negative EMI sources and achieving EMC improvements. Finally, levels of conductive EMI are estimated with DFT, and experimentally verified to comply with the CISPR 25 (or EN 55025) regulations. Moreover, it is clearly shown, that limited speed PWM driving of the power switches with appropriate snubber circuits guarantees reduced conductive EMI. When considering the price and high EMC, in the final solution the power converter is driven by the mu-controller PIC16F876 with limited numerical and peripheral capabilities, where only normal PWM and randomized PWM can be implemented

Differential Mode Input Filter Design for a Three-Phase Buck-Type PWM Rectifier Based on Modeling of the EMC Test Receiver

Abstract: For a three-phase buck-type pulsewidth modulation rectifier input stage of a high-power telecommunications power supply module, a differential-mode (DM) electromagnetic compatibility (EMC) filter is designed for compliance to CISPR 22 Class B in the frequency range of 150 kHz-30 MHz. The design is based on a harmonic analysis of the rectifier input current and a mathematical model of the measurement procedure including the line impedance stabilization network (LISN) and the test receiver. Guidelines for a successful filter design are given, and components for a 5-kW rectifier prototype are selected. Furthermore, formulas for the estimation of the quasi-peak detector output based on the LISN output voltage spectrum are provided. The damping of filter resonances is optimized for a given attenuation in order to facilitate a higher stability margin for system control. Furthermore, the dependence of the filter input and output impedances and the attenuation characteristic on the inner mains impedance are discussed. As experimentally verified by using a three-phase common-/Differential-Mode separator, this procedure allows accurate prediction of the converter DM conducted emission levels and therefore could be employed in the design process of the rectifier system to ensure compliance to relevant EMC standards

Inverter EMI modeling and simulation methodologies

Abstract: A numerical prediction of electromagnetic interference (EMI) allows evaluation of EMI performances at the design stage and before prototyping. It can also help reduce the post-prototype electromagnetic compatibility cost by minimizing late redesign and modifications of a drive implementation. This paper describes two simulation approaches with time- and frequency-domain simulations and verifies them with experimental results. Both time- and frequency-domain simulation approaches are found effective as long as the noise source and propagation path are properly modeled. The three-dimensional (3-D) finite-element-analysis (FEA)-based parasitic parameter extraction tool-Ansoft Spicelink has been used substantially. To gain additional degree of confidence, the results obtained from FEA are verified with closed-form solutions and actual measurements.

Modular-Terminal-Behavioral (MTB) Model for Characterizing Switching Module Conducted EMI Generation in Converter Systems

Abstract: This paper proposes a new frequency-domain modular-terminal-behavioral (MTB) modeling approach for characterizing conducted electromagnetic interference (EMI) noise sources in a converter. It models the EMI emission of a switching device module under specific switching conditions using a three-terminal equivalent Norton network, which can be extracted from a standard test. Experiments show that the MTB model can be used to accurately predict the EMI noise in a converter for the entire conducted EMI frequency range. It is more general and more accurate than the existing behavioral models, especially in the high frequency range, and it is more convenient than the physics-based model. The study also verifies the importance of EMI source impedance modeling and interactions between common mode and differential mode noises

Design of Inductor Winding Capacitance Cancellation for EMI Suppression

Abstract: In this paper, the parasitics in both differential-mode (DM) and common-mode (CM) inductors are first discussed. The methods for both DM and CM inductor winding capacitance cancellation are then proposed. Prototypes are designed and tested, using a network analyzer. Finally, the prototypes are applied to practical power converters and electromagnetic interference (EMI) is measured. Both small signal measurement and practical EMI measurement prove that the proposed methods can efficiently reduce the effects of winding capacitance and therefore improve the inductor's filtering performance

Acousto-optical PD detection for transformers

Abstract: Partial discharge (PD) is one of the factors that could lead to failure of power transformers, leading to power outage and expensive repairs. The acoustic wave induced by PD can be measured and used for monitoring, diagnosing, and locating potential failures in the transformers. Fiber optic sensors have been shown to be attractive devices for PD detection because of a number of inherent advantages including small size, high sensitivity, electrical nonconductivity, and immunity to electromagnetic interference. A fiber optic sensor based on a Fabry-Perot interferometry is constructed by a simple micromachining process compatible with microelectromechanical system technology. The sensors are used in a transformer to measure PD acoustic waves. The experimental results show the sensor not only has an inherent high signal to noise capability, but is able to accurately localize the PD sources inside the transformer.

Multiple Slope Switching Waveform Approximation to Improve Conducted EMI Spectral Analysis of Power Converters

Abstract: An improved and simplified electromagnetic interference (EMI) modeling method based on multiple slope approximation of device-switching transitions for EMI analysis of power converters is presented. The traditional noise source modeling method, which uses single slope for rise and fall transition, is studied, and the criteria for reasonable modeling in the frequency range is analyzed. The turn-on and turn-off dynamics are investigated by dividing the nonlinear transitions into several stages based on an insulated gate bipolar transistor (IGBT) behavior circuit model. Real device-switching voltage and current waveforms are approximated by piece-wise linear lines and modeled by multiple dv/dt and di/dt slopes. The predicted EMI spectra suggest that high-frequency EMI noise is modeled with an acceptable accuracy. The proposed method was verified experimentally for a dc-dc buck converter

An EMC evaluation of the use of unshielded motor cables in AC adjustable speed drive applications

Abstract: The most common solution for modern adjustable speed drives (ASD) is the use of induction motors (IM) fed by voltage-source inverters (VSI). The inverter generates a pulsewidth modulated (PWM) voltage, with dv/dt values of about 6 kV//spl mu/s or even more. In three-leg inverters for three-phase applications the occurrence of common-mode voltage is inherent due to asymmetrical output pulses. As a result, for electromagnetic compatibility (EMC) reasons, in most applications shielded cables are used between the inverter and the motor, implying high installation costs. The present paper discusses the use of cheaper, unshielded cables from an EMC point-of-view. A new method for measuring electromagnetic interference (EMI) from unshielded cables is proposed and measurement results are presented. The level of EMI is evaluated in different situations: without an output filter, with a classical LC output filter and with an advanced output filter with dc link feedback. It is concluded that, from an EMC point of view, unshielded cables can give very good performance provided that a common-mode (CM) output filter is used.

Identification of Essential Coupling Path Models for Conducted EMI Prediction in Switching Power Converters

Abstract: A knowledge of conducted electromagnetic interference (EMI) generation and propagation mechanisms can aid the engineers working in the field of electromagnetic compatibility (EMC) This paper presents a method, called essential coupling path models, to investigate the conducted EMI coupling in switching power converters Three modes of conducted EMI noise: the mixed-mode (MM), the intrinsic-differential-mode (IDM), and the common-mode (CM) are identified by time domain measurements associated with an ac-dc half-bridge converter The derived models assume that the lumped parameters' circuits represent the noise generation and propagation paths that allow easy physical interpretations The experimental results show good agreement by the comparison of measured and predicted MM, IDM, and CM noise emissions with filter included The proposed method is easy to apply in practice for understanding, diagnosis, and evaluation of EMI behavior

Coupling reduction in enclosures and cavities using electromagnetic band gap structures

Abstract: The physical mechanism behind electromagnetic interference (EMI) is the coupling of energy between different primary and secondary sources of radiation and components within the package or chassis. This coupling can be either through conduction or radiation. However, regardless of the coupling mechanism, surface currents are needed to support the electromagnetic fields that eventually cause radiation, which in turn, constitute the EMI in the victim component. Minimizing these surface currents is considered a fundamental and critical step in minimizing EMI. In this work, we address novel strategies to confine surface currents. Unlike the traditional use of lossy materials and absorbers, which can be costly and can suffer from considerable disadvantages including mechanical and thermal reliability leading to limited life time, we consider the use of electromagnetic band gap (EBG) structures. These structures are inherently suited for surface current suppression. Their design is straightforward, and they are inexpensive to implement and do not suffer from the limitation of the previous methods used for the type of EMI suppression previously described. The effectiveness of the EBG as an EMI suppresser will be demonstrated using numerical simulations and measurements.

A Systematic Design to Suppress Wideband Ground Bounce Noise in High-Speed Circuits by Electromagnetic-Bandgap-Enhanced Split Powers

Abstract: In this paper, the split power planes with electromagnetic bandgap structures enhancement is proposed for the wideband suppression of ground bounce noise in high-speed printed circuit boards. A systematic design procedure is presented, featuring a modified analytic design formula, a novel compact electromagnetic bandgap layout, and a discussion on the minimum number of cascaded rows. As it is capable of selectively suppressing the ground bounce noise at several desired frequencies, the approach is applied to deal with the coupled noise between two isolation islands and the ground bounce noise induced by signal line crossing the split power planes. Successful noise suppression over an ultrawide band from dc to 5 GHz and reduction of the peak ground bounce noise in the time domain by 75% by an electromagnetic bandgap strip 1.44 cm wide is demonstrated. Good agreement is seen from the comparison between simulation and experimental results

Fast transient analysis of incident field coupling to multiconductor transmission lines

Abstract: Due to the rapid surge in operating frequencies and complexity of modern electronic designs, accurate/fast electromagnetic compatibility/interference analysis is becoming mandatory. This paper presents a closed-form SPICE macromodel for fast transient analysis of lossy multiconductor transmission lines in the presence of incident electromagnetic fields. In the proposed algorithm, the equivalent sources due to incident field coupling have been formulated so as to take an advantage of the recently developed delay extraction based passive transmission line macromodels. Also, a method to incorporate frequency-dependent per-unit-length parameters is presented. The time-domain macromodel is in the form of ordinary differential equations and can be easily included in SPICE like simulators for transient analysis. The proposed algorithm while guaranteeing the stability of the simulation by employing passive transmission line macromodel, provides significant speed-up for the incident field coupling analysis of multiconductor transmission line networks, especially with large delay and low losses

Surface-mountable EMC monopole chip antenna for WLAN operation

Abstract: A novel surface-mountable monopole chip antenna having an electromagnetic compatibility (EMC) property is presented. In addition to the radiating strip on the chip base of the antenna, a ground portion is added on the side surfaces of the chip base. The antenna ground portion is to be grounded to the system ground plane of the mobile device for practical applications. The antenna ground portion can function as an effective shielding wall between the antenna and the nearby electronic components in the device. In this case, the nearby components can be placed in close proximity to the antenna, with small effects on the antenna performances. That is, the proposed antenna is EM compatible with the nearby components. In addition, the proposed antenna is surface-mountable onto the system circuit board of the mobile device, which reduces the packaging cost of the device. The proposed antenna applied to a smart phone or Personal Digital Assistant (PDA) phone for WLAN operation in the 2.4 GHz band is studied in the paper.

Common mode EMC input filter design for a three-phase buck-type PWM rectifier system

Abstract: The EMC input filter design for a three-phase PWM rectifier is usually separated into the design of the differential (DM) and of the common mode (CM) stage. While for the DM filter part design rules and procedures are well-known and the parameters are easier to derive, the CM filter design is often based on trial-and-error methods and/or on the experience of the designer. In this work, a comprehensive design procedure for a CM EMC input filter is performed exemplarily for a three-phase three-switch buck-type PWM rectifier with an integrated boost output stage. A simplified model of the CM noise propagation is developed and the relevant parasitic impedances are identified. A capacitive connection from the star-point of the DM input filter to the capacitive centre point of the rectifier output voltage is proposed and the effect of this measure concerning CM EMC is verified. Finally, a two stage CM filter is designed and the compliance to the conducted emission requirements of CISPR 22 class A is verified through measurements on a 5 kW prototype.

Predicting parasitics and inductive coupling in EMI-filters

Abstract: The challenge of EMC is a crucial aspect regarding the reliability of power electronic applications. State-of-the-art in assuring EMC in the radio frequency range are low-pass-filters with passive components. The nowadays filter design is characterized by a trial-and-error-process which is the more efficient the more experienced the designer is. An accurate prediction of EMI-filters' insertion loss requires the correct calculation of mutual coupling between the circuits' components as well as of the components parasitics. It does need some experience to define crucial points of coupling and it would be best to calculate them by a field solver like the PEEC-method, which has become state-of-the-art in high speed chip design. In this paper it is shown that the prediction of EMI-filter performance can be improved by implementing coupling calculation on the basis of simple formulas, when using a field solver is not wanted.

Radio frequency electromagnetic fields in large conducting enclosures: effects of apertures and human bodies on propagation and field-statistics

Abstract: Radio frequency propagation in an electrically large resonant chamber (a screened room) was simulated by two models: a statistical combination of multiple resonant modes and a computational electromagnetic simulation [the transmission line matrix (TLM) method]. The purpose of this work was to investigate the effects of passengers and windows on electromagnetic fields (EMF) in aircraft and other vehicles. Comparison of the multimode models with measurements made in a screened room showed that as the electromagnetic losses increased, the transmission between two internal antennas was reduced, and there were fewer turning points in its frequency response. The autocorrelation of this frequency response provided a useful estimate of the composite Q-factor of the resonances and showed that the Q of the chamber was reduced from a value of the order of 10 000 when emptied to 1000 when windows were added and when filled with people to 100. The TLM simulation provided further useful information about the statistical variation of electric field strength with position.

Single-phase inverter circuit for conditioning and converting dc electrical energy into ac electrical energy

Abstract: The invention presents a structure for converting AC electrical energy into DC electrical energy, characterized in that it is simple, has a high performance and minimizes the problem of electromagnetic compatibility. In its first preferred embodiment, the circuit includes six switching elements governed by a control unit, four commutators forming a H-bridge (T1, T2, T3, T4) and two auxiliaries (T5D, T6D), and two auxiliary diodes (Daux1 and Daux2). The H-bridge elements switch to mains frequency whilst T5D and T6D switch to high frequency by means of pulse width modulation (PWM) or other appropriate modulation techniques. The voltage of these auxiliary switching elements (T5D, T6D) is limited topologically to half the input direct voltage (Vin), thereby reducing switching losses and providing a high-performance converter.

Emc design fundamentals

Abstract: Summary form only given. Virtually every electronic device or system designed today is required to comply with EMC standards. Proper EMC design, throughout the development cycle, is necessary to cost-effectively ensure that products operate reliably in their intended electromagnetic environment without being susceptible to electrical noise from other devices, or generate excessive noise that can interfere with other devices. Meeting this goal has become especially challenging in recent years, due to the ever-growing use of electronics, increasing clock frequencies and escalading wireless-bandwidth demands. Products that do not comply with the applicable EMC requirements, can be blocked from markets, and/or can create interoperability issues with consequences ranging from a minor annoyance to death. EMC standards have been established by several agencies including the Federal Communication Commission (FCC), the US Military, the European Union (EU) and the Radio Technical Commission for Aeronautics (RTCA). Although numerous standards exist, they have a common fundamental theme; to establish a maximum limit on emissions and to establish a minimum level on susceptibility (immunity). To understand the impact of EMC on design, it is first necessary to understand the fundamental concepts of electromagnetic interference and electromagnetic compatibility. For an EMC problem to exist, three components are necessary: a source that generates the interference, a device that is susceptible to the interference, and a coupling path. The coupling path can be conducted (through power and/or signal lines) or radiated (magnetic, electric or plane wave). Fortunately several options exist for mitigating EMC issues. The effectiveness of the coupling path can be reduced (i.e. the isolation between the source and the susceptible device can be improved) through the use of increased separation, shielding, filtering, interconnection modifications, or a combination of these. Furthermore, the source can be modified to reduce the interference generated. Many of the techniques used to reduce the interference generated by the source can also be used to improve the immunity of the potentially susceptible device. These techniques include the routing of signals closer to ground planes and the operating frequency selection. System partitioning is also critical. Fundamentally, devices that are inherently noisy (such as power converters) should be located as far as practical from devices that require a low noise floor (such as wide dynamic range analog/digital converters). In larger/more-complex systems, signal and power distribution become an important component of the EMC design. An often-overlooked area is EMC design process. To cost-effectively ensure that products operate reliably in their specified electromagnetic environment, proper EMC practice must be considered throughout the development and manufacturing cycles. Since EMC can potentially affect all aspects of a product design (mechanical, electrical and system) it is often necessary to develop and maintain an EMC control plan that details the technical and administrative processes necessary to flow down the EMC requirements to all applicable portions of the product.

Quantifying electric and magnetic field coupling from integrated circuits with TEM cell measurements

Abstract: One of the most widely used methods for evaluating the electromagnetic compatibility of integrated circuits (ICs) involves mounting the IC on a printed circuit board embedded in the wall of a TEM cell. TEM cell measurements are influenced by both electric and magnetic field coupling from the IC and its package. This paper describes how a TEM cell and a hybrid can be used to isolate electric field coupling from magnetic field coupling. Knowledge of the dominant field coupling mechanism can be used to troubleshoot radiated emissions problems due to ICs.

Magnetic fields and loop Voltages inside reduced- and full-scale structures produced by direct lightning strikes

Abstract: This paper presents a numerical electromagnetic analysis of magnetic fields and loop voltages inside reduced- and full-scale lightning protection systems (LPSs) "structures" resulting from direct lightning strikes. The method of moments is employed to model the whole structure in three dimensions except the lightning channel. The lightning channel is simulated by the well-known transmission-line model (TL model), where the influence of the lightning-channel generated electric and magnetic fields are taken into account. Three distinct LPSs were modeled, namely, reduced-scale model with return conductors (RSRC), reduced-scale model with lightning channel (RSLC), and full-scale model with lightning channel (FS). The computed results of magnetic fields and magnetic-field derivatives were verified versus some experimental results for the RSRC model. In addition, the scale factor for all the measured quantities were also checked as functions of the geometrical scale factor for the positive and the negative first stroke currents. The lightning shielding performance with and without bonding was investigated for three distinct lightning stroke types, namely, the negative first, the negative subsequent, and the positive strokes. The voltages and currents generated in loops located inside the struck FS LPS were computed with and without bonding and grounding resistance and for different lightning current waveforms, locations and inclination of the lightning channel, and return stroke velocity.

A multipurpose FDTD-based two dimensional electromagnetic virtual tool

Abstract: A novel, multipurpose, FDTD-based two-dimensional electromagnetic virtual tool has been designed and introduced. A variety of electromagnetic problems, including radio wave indoor/outdoor, urban/rural propagation, electromagnetic compatibility, resonators, closed/open periodic structures, and linear and planar arrays of radiators can be simulated. This paper describes the software and its use in electromagnetics courses

New mathematical descriptions of ESD current waveform based on the polynomial of pulse function

Abstract: The transient near-field of the electrostatic discharge (ESD) is strongly affected by the discharge current waveform. After analyzing several typical mathematical descriptions of the ESD current for the contact mode, two new mathematical descriptions of ESD current were constructed according to the polynomial of pulse function. These descriptions have the continuity of the first derivative at t=0 and are time-integrable. They proved to have little relative error compared to the IEC61000-4-2 standard

The transmission line modelling method (tlm) applied to the simulation of tem cells and shielded enclosures

Abstract: This paper presents the use of the TLM-TD (Transmission Line Modelling - Time Domain) method to analyse TEM (Transversal Electromagnetic Mode) cells and shielded enclosures. TEM cells are used to produce calculable electric and magnetic field strengths that establish standard electromagnetic fields for EMC (Electromagnetic Compatibility) tests. However, as resonance cavities, TEM cells may produce undesired field strength variations caused by non-TEM-waves propagating inside it. In this work, the TLM method is applied to investigate resonance frequencies in a Crawford and a TEM cell based on the topology of a GTEM (Gigahertz Transversal Electromagnetic Mode) cell. Finally, the TLM is used for analysing the shielding effectiveness of enclosures with multiple slots and apertures. The numerical models presented in this article are based on the SCN (Symmetrical Condensed Node). The simulations are compared with another methods as well as experimental results.

Earth conduction effects in systems of overhead and underground conductors in multilayered soils

Abstract: Electromagnetic interference calculations in the case of overhead lines and underground insulated conductors require the determination of the self and mutual impedances of all conductors in the arrangement. For the calculation of these impedances in nonhomogeneous soils, the use of the finite-element method is suggested. However, this is generally a complicated and time-consuming task. Analytic expressions for these impedances are derived by a solution of the electromagnetic field equations for the case of n-layer soil. The infinite integrals involved are evaluated using a numerically stable and efficient integration scheme. A typical transmission line/underground insulated pipeline arrangement is examined for various two-layer earth models and over a wide frequency range. The validity of the proposed methodology is justified by a proper finite-element method formulation. The inclusion of earth stratification leads to substantially different results for the calculated impedances. These differences affect significantly the levels of voltages and currents induced on the pipeline, even for power frequencies, justifying the need for a more detailed earth model representation.

EMC Computer Modeling Techniques for CPU Heat Sink Simulation

Abstract: This paper presents finite-element frequency domain results for electromagnetic radiation emitted from high power microelectronic circuits connected to a heat sink. The heat sink model associated with one of the IEEE EMC challenging problems has been used to investigate three different grounding configurations. A new simulation model for the Intel P4 CPU heat sink is proposed and analyzed. A resonant frequency of 2.6 GHz with a reflection coefficient of 8.3 dB was found for the CPU heat sink. This is close to the IEEE and Bluetooth wireless communication system's operating frequency of 2.4 GHz. An optimal design of the CPU heat sink design should be performed in order to minimize the radiated emission from the CPU heat sink