Showing papers on "Conducted electromagnetic interference published in 2015"

EMI Reduction via Spread Spectrum in DC/DC Converters: State of the Art, Optimization, and Tradeoffs

Abstract: Spread spectrum is a technique introduced for mitigating electromagnetic interference (EMI) problems in many class of circuits. In this paper, with particular emphasis on switching DC/DC converters, we consider the most common and most efficient known spreading techniques, looking for spreading parameters that ensure the highest EMI reduction and the lowest performance reduction in the circuit where the spreading is applied. The result is an interesting tradeoff not only between EMI reduction and performance drop, but also on the EMI reduction itself when considering different EMI victim models. The proposed analysis is supported by measurements on two switching DC/DC converters: 1) based on pulse-width modulation and 2) based on the resonant converter class.

The Worst Conducted EMI Spectrum of Critical Conduction Mode Boost PFC Converter

Abstract: The switching frequency of the boost power factor correction (PFC) converter operating in critical conduction mode (CRM) varies in a line cycle, making the conducted electromagnetic interference (EMI) spectra of the converter appear great differences under different input voltage and load conditions. The EMI filter should be designed according to the worst conducted EMI spectrum of the converter, so as to suppress the conducted EMI of the converter to be lower than the standard limits under all working conditions. This paper analyzes the characteristics of the common-mode (CM) and differential-mode (DM) noise spectra of the CRM boost PFC converter, and discusses the effects of the varied switching frequency on the peak, quasi-peak (PK), and average (AV) conducted EMI spectra. It is revealed that, for the conducted EMI limits defined in EN55022 class B, which are specified within 150 kHz to 30 MHz, the EMI filters required for suppressing the QP spectra of the conducted EMI of the CRM boost PFC converter are larger than that for suppressing the AV spectra, and the QP values of the conducted EMI under all working conditions are lower than a certain maximum boundary. The input voltage and load conditions for the worst CM and DM noise spectra of the converter are derived in this paper, thus the repetitive measurements and numerical calculations are avoided. A CRM boost PFC converter prototype is fabricated, and the evaluation of the measured conducted EMI spectra and the EMI filter design example verified the theoretical analysis.

An Investigation of Electromagnetic Radiated Emission and Interference From Multi-Coil Wireless Power Transfer Systems Using Resonant Magnetic Field Coupling

Abstract: Wireless power transfer (WPT) technology has recently emerged as an innovative and promising technology, and its electromagnetic compatibility (EMC) has become a significant issue. In this study, we investigated the electromagnetic (EM) radiated emission and interference generated by WPT systems using resonant magnetic field coupling, especially in applications with multi-coil configurations. The change in coil resonance associated with multi-coil configurations was analyzed via the impedance profile. We measured the EM radiated emission and analyzed the results with respect to the coil resonance. An analog-to-digital converter chip was designed and fabricated to analyze the effect of electromagnetic interference (EMI). Based on measurement and simulation results, we verified that the EM radiated emission and interference increase at the series or parallel resonance peaks, depending on the source type. In addition, we verified that EMI can be reduced by using ferrite sheet shielding.

Conducted EMI Spectra of Average-Current-Controlled Boost PFC Converters Operating in Both CCM and DCM

Abstract: The average-current-controlled boost power factor correction converter may operate in all-continuous current mode (CCM), part-CCM/discontinuous current mode (DCM), or all-DCM mode in a half line cycle under different input voltage and load conditions, and the conducted electromagnetic interference (EMI) spectrum of the converter exhibits differences in these operation modes. In this paper, by analyzing the characteristic of the harmonics of the drain-to-source voltage of the power switch, the characteristics of the common-mode and differential-mode noise of the converter are revealed in different operation modes. The analyzed results can be used to guide the EMI filter design for the converter and ensure the conducted EMI satisfying the standard under all working conditions.

Modeling the external electromagnetic influences on the complex electronic equipment

Abstract: The paper discusses the electromagnetic topology technique for modeling by influence external electromagnetic field on the complex electronic equipment. In this paper we describe an example of modeling the influence of electromagnetic impulse on the complex electronic equipment.

Suppression for Discharging Bearing Current in Variable-Frequency Motors Based on Electromagnetic Shielding Slot Wedge

Abstract: High-frequency current in the bearings of variable-frequency motors coupled with their shafts is a common issue that will shorten the bearings lifetime ultimately. A new method, which could be used to suppress high-frequency discharge bearing current, was proposed in this paper. In this method, an electromagnetic shielding slot wedge (ESLW) was used to reduce the capacitive coupling between the stator windings and the rotor. The electromagnetic coupling resulted from the common-mode voltage could be blocked by this electromagnetic shield layer. In addition, the mathematical model of the suppression method was given and the high-frequency electromagnetism performance of the motor was analyzed. Finally, an experimental platform was setup and a motor was modified to evaluate the suppressing effectiveness. The shaft voltage, bearing currents, and the general features of the modified motors, with and without ESLW, were measured and compared.

A Measurement Setup for Quantification of Electromagnetic Interference in Metallic Casings

Abstract: In this paper, a test setup is proposed for quantification of electromagnetic interference (EMI) in an enclosure of digital systems. Small probes at the casing walls are used to measure the internal fields and derive network parameters for the typical coupling between internal components. It is shown that the setup is viable for estimating EMI between enclosed components in a frequency range from ${\bf 10}\,\text{MHz}$ to ${\bf 6}\,\text{GHz}$ . Measurement results from the proposed setup are in excellent agreement with those of analytical and numerical methods. A statistical approach is introduced to evaluate the measurement results from a twelve-port vector network analyzer at high frequencies above the first resonance. Using this approach, typical components in digital systems are analyzed and simplified geometrical models are given. These models allow full-wave simulations of realistic setups with feasible computation times. A good model-to-hardware correlation between simulation and measurement results over the whole frequency range is achieved. It is demonstrated that the proposed measurement and evaluation approach of the fabricated cavity shows the same characteristic behavior of a real office workstation with internal components.

Trace Orientation Function for Statistical Prediction of PCB Radiated Susceptibility and Emission

Abstract: In this paper, trace orientation function (TOF) is proposed for statistical prediction of printed circuit board (PCB) radiated susceptibility and emission. This function relates the orientations and angle of incident electromagnetic wave to the location of a trace in wiring distribution of electronic board. For both susceptibility and emission of signal traces, TOF is a compact function that considers the location, orientations, and its probability of distribution. By using the TOF, one can estimate the radiated susceptibility and emission of a PCB for different points of view and derive a safe spatial region to increase the electromagnetic compatibility of electronic systems. In addition, the TOF helps to predict the electromagnetic compatibility of a system before the final step of its PCB implementation. To show the accuracy and effectiveness of TOF concept, the method is applied on a board and the results are compared with CST field solver simulations. The simulation result shows 8.1% error between statistical method and full-wave analysis for maximum electric far field of the board and maximum 42.4% error for average induced voltage on whole traces. Also, an analytic circuit level method is proposed for estimating the current amplitude of modeling dipoles, based on power consumption of the electronic system on PCB.

Differential-mode EMI emission prediction of SiC-based power converters using a mixed-mode unterminated behavioral model

Abstract: With the high electromagnetic interference (EMI) noise generated by fast-switching-speed devices, it is crucial to learn about EMI noise generation and propagation in the systems and design effective EMI filters. EMI behavioral models have been verified as an effective tool to predict common-mode (CM) and differential-mode (DM) EMI noise and aid in EMI filter design. However, these models cannot predict the effect of the cross-coupled DM and CM noise, which is more likely to be present when operating at a high switching frequency. Accordingly, this paper explains the cross-coupled effect that noise generation and propagation have in an inverter system. A mix-mode unterminated behavioral model is proposed to capture the DM noise at the input DC terminals considering the mixed CM effect. The model accuracy is verified to 30 MHz in experiments carried out on a three-phase SiC MOSFET inverter.

Research and realization of a novel active common-mode EMI filter

Abstract: Voltages and currents of high power density power electronic circuits vary rapidly for its high speed switching, which results in serious electromagnetic interference (EMI) problems. The conventional used EMI filters are made of passive inductors and capacitors. Its size is usually comparable to that of the converter itself. As to this, active EMI filters (AEF) made of amplifiers and transistors are proposed. In this paper, a novel AEF topology used for DC-DC power converters is proposed. The most distinguished feature of this filter is that it shares the same power supply with the DC-DC converter. Thus, the size and weight of the whole filter is reduced to a great extent. The experimental results show that the proposed filter worked well and could attenuate the noise with high effectiveness.

Performance Analysis of Linear Induction Motor of Electromagnetic Catapult

Abstract: Based on the operating principle of linear induction motor (LIM), this paper has analyzed the performance of the LIM consisting of a long sectioned transverse flux stator and a short flat aluminum mover, proposed the basic requirements and working modes of this special type of a catapult, described the optimal design methods of the LIM and discussed in detail some important parameters affecting the operating performance, such as the slot width, pole pairs, and the thickness of the mover. Then, the optimal system design and the discussion of performance are carried out based on the T-type equivalent circuit model with the covered and uncovered sections. The phase current, phase voltage, power capacity, and height are 11359 A, 3000 V, 409 MVA, and 1.73 m, respectively. The launch profile is also derived from the model. To verify the electromagnetic compatibility of the LIM, the 3-D magnetic model is established. The results show that the magnetic fields fall to the earth's ambient level at 1 m above the stator, which cannot bring low-frequency electromagnetic interference to the environment.

The Input Impedance of Common-Mode and Differential-Mode Noise Separators

Abstract: This paper discusses the $\Delta$ -networks and other circuits designed to separate the conducted electromagnetic interference (EMI) into its common mode (CM) and differential mode (DM) components. The input impedances of CM/DM separators must be 50 $\Omega$ resistive in the measurement frequency range, and they must be independent of the values of the noise signals and noise source impedances. The conditions for achieving such input impedances are derived. It is shown that many of the proposed separators, including the $\Delta$ -network suggested in the International Special Committee on Radio Interference (CISPR) 16-1-2 standard, do not fulfill the input impedance requirement. This leads to unreliable CM and DM measurements and, consequently, to the oversizing of EMI filters and design by trial and error.

Electromagnetic interference simulations of power electronic modules

Abstract: At higher frequencies, EMI emissions of a power electronic module largely depend on the layout and area of the current conduction paths. In this paper, EMI simulations are compared between a coplanar module and a three-dimensional (3D) module. The EMI simulations were performed using 3D EM simulation software. The EMI emission, in terms of DC-bus bar capacitances, of a balanced and unbalanced power electronic module is investigated. It is concluded that a three-dimensional multilayer approach is more suitable for addressing the issue, both in terms of reducing parasitic inductance and minimizing EMI effects. Also, care should be taken to design balanced bus bars to minimize EMI noise.

Contribution of Electromagnetic Perturbation to the Transient Response of an Electronic Circuit Exposed to a High Multi-MeV X-Ray Flux

Abstract: The contribution of the electromagnetic field to the electric response of a circuit exposed to high x-ray flux is quantified based on a novel approach which combines both experimental and numerical tools. First, we describe the method used to quantify the ionizing and electromagnetic stress induced by the x-ray beam in free space as well as on the target circuit. Next we show the perturbation resulting from the x-ray irradiation of an analog circuit. Also, we present the effect of an electromagnetic plane wave on the electric response of the circuit. Based on the comparison of experimental results, we demonstrate that electromagnetic fields coupling resulting from photoelectrons produced by the x-ray/circuit interaction is similar to the coupling induced by an external electromagnetic plane wave.

EMI Prediction of Switching Converters

Abstract: This paper addresses the simulation of the conducted electromagnetic interference produced by circuits with periodically switching elements. The proposed method allows for the computation of their steady-state responses by means of augmented linear time-invariant equivalents built from circuit inspection only, and standard tools for circuit analysis. The approach is demonstrated on a real dc–dc boost converter by comparing simulation results with real measurements.

The reviews of integrated EMI filters applied in power electronic system

Abstract: With the process of miniaturization, modularization and integration in power electronic systems, the requirements for EMI filters are much higher than before. However, the large volume and parasitic parameters of passive components have great influence in the high frequency performance of conventional EMI filters. With the development of electromagnetic integration technologies, integrated EMI filter with its advantage of highly integrated volume and small parasitic parameters has become a new research direction. At present, the research directions of integrated EMI filter include the integrated EMI filter based on flexible multi-layer foil, planar EMI filter, bus-bar EMI filter and so on. The structures and principles of the integrated EMI filter above are analyzed in this paper, and based on the analysis; the applicable occasions and future trends of these EMI filters are investigated.

Electromagnetic induction field communication

Abstract: Consistent with an example embodiment there is an electromagnetic induction field communication system, illustratively, for communicating on or around the body Two transceivers (or receiver and transmitter) contain coils and capacitors suitable for generating an electromagnetic induction field surrounding the body and are capable of communicating therebetween

Fast prediction for conducted EMI in flyback converters

Abstract: The flyback switched mode power supply often fails in electromagnetic compatibility (EMC) because of the easily aroused conducted electromagnetic interference (EMI). However, the measurement of conducted EMI during initial compliance tests requires strict test environments and expensive facilities, this makes the prediction of EMI important. This paper presents a time domain simulation method to predict the conducted EMI of a flyback converter before prototyping. The CST PCB Studio is utilized to extract parasitic parameters of a printed circuit board (PCB) based on 2D field solver and perform total circuit simulation. Experimental results validate that the presented modeling method is efficient and fast to predict EMI.

Measuring the shielding effectiveness and reflection of electromagnetic field of building material

Abstract: Exposure to electromagnetic radiation is omnipresent. And we can expect the volume of electromagnetic radiation as well as the number of sources to continue to increase. This paper deal with the measuring of shielding effectiveness and reflection of electromagnetic field. The aim is to measure the shielding effectiveness and reflection in the range of high frequencies from 1 GHz to 9 GHz by step of 0.2 GHz. In this paper, the object of investigation is a brick wall with a thickness of 0.25 m and the surface area of 2×2 m. Measurements were performed according to the IEEE Standard, Method for Measuring the Effectiveness of Electromagnetic Shielding Enclosures. Measurements were performed in the non-reflection chamber in order to avoid the exterior influence. The brick wall was made of bricks type “Horizontally Perforated Clay” of the size 0.25c0.25 m.

Analysis of EMI reduction methods of DC-DC buck converter

Abstract: The electromagnetic interference (EMI) generated from the DC-DC buck converter effects the performance of integrated circuits which receive power supply from the buck converter. In this paper, the EMI reduction techniques of DC-DC buck converter are presented. The damping resistor is applied to reduce the output noise of the buck converter. In time domain, this damping resistor technique reduces the output noise of the buck converter significantly but is not effective in reducing high frequency noise components. To resolve this issue, PCB design is modified to contain separate planes for input, output, switching, and ground ports. The TEM-cell, measurement results show that with this modification in addition to the damping resistor, the EMI is significantly reduced over a wide range frequency up to 1GHz.

Electromagnetic interference shielding for system-in-package technology

Abstract: Embodiments are generally directed to electromagnetic interference shielding for system-in-package technology. An embodiment of a system-in-package includes a substrate; chips and components attached to the substrate; dielectric molding over the chips and components; and an electromagnetic interference (EMI) shield. The EMI shield formed from a conductive paste, and the EMI shield provides a combined internal EMI shield between chips and components of the system in package and external EMI shield for the system-in-package.

Integrated circuit having electromagnetic shielding capability and manufacturing method thereof

Abstract: The present invention discloses an integrated circuit having electromagnetic shielding capability and the manufacturing method thereof. An embodiment of the said integrated circuit comprises: a semiconductor circuit structure including a first surface which covers an electromagnetic radiation area; an electromagnetic shielding layer covering the first surface and including at least one contact; and at least one conducting path operable to electrically connect the at least one contact with a steady voltage and thereby shield off the electromagnetic wave from the electromagnetic radiation area, wherein the current running through the electromagnetic shielding layer is zero or less than the maximum current running through the electromagnetic radiation area.

Conducted electromagnetic interference simulation model with non-linear behaviour of transformer

Abstract: Using a flyback converter as a case study, an electromagnetic interference (EMI) simulation model including the non-linear behaviour of an isolation transformer is developed. To take into account the non-linearity of the transformer in the circuit simulation, the Jiles-Atherton (J-A) model that handles the non-linear behaviour of the magnetic core is proposed. As the non-linearity of the transformer affects mainly the differential-mode (DM) conducted EMI but not the common-mode conducted EMI, the simulation and experimental results presented in the study will focus on DM conducted EMI. The ability to include the non-linear behaviour of a magnetic component in a power converter yields more realistic prediction that reflects the actual operating condition of the power converter, which prevents underestimation of DM conducted EMI.

A comparison between boundary and continuous conduction modes in single phase PFC using 600V range devices

Abstract: This paper presents an analysis and comparison of boundary conduction mode (BCM) and continuous conduction mode (CCM) in single phase power factor correction (PFC) applications. The comparison is based on double pulse tester (DPT) characterization results of state-of-the-art superjunction devices in the 600V range. The measured switching energy is used to evaluate the devices performance in a conventional PFC. This data is used together with a mathematical model for prediction of the conducted electromagnetic interference (EMI). This allows comparing the different devices in BCM and CCM operation modes and evaluating the performance as a function of the PFC power density and efficiency.

Electromagnetic Shields of the Air-Core Compulsator

Abstract: Air-core compulsator is a specially designed generator capable of delivering high current pulses to a low-impedance load, such as the electromagnetic railgun. Due to the absence of ferromagnetic material, the field strength in air-core compulsator can reach 4-6 T. Therefore, electromagnetic shields are required to protect the surrounding operators and instruments from exposure to high magnetic fields. This paper investigates the design methodology of the shield as well as its influence on the performance of the machine. A dynamic model is built to analyze the shielding effect and its performance tradeoffs of a reference compulsator. The result indicates that the effect of the eddy-current shield is much better than the magnetic shield using ferromagnetic material, due to the high frequency and the magnetic saturations. The magnetic field can be completely screened inside the conducting shield, at the expense of some electrical, mechanical, and thermal performance. Since the eddy-current density is sensitive to the location of the shield, the influences of the conducting shield are parametrically analyzed. Using the electromagnetic and thermal coupling field link, the temperature rise of the shield is also calculated. Analysis results can provide the theoretical guides for the shielding of the air-core compulsator investigation in the future.

Coaxial data communication with reduced EMI

Abstract: Data communication having improved electromagnetic interference (EMI) rejection when communicating through a coaxial cable is provided by using differential transmission and/or reception through a common-mode choke and a dissipative element resulting in extremely low radiated emissions and high immunity to external radiation interference in a low-cost way.

High speed PCB & spiral with patch EBG planar integration for EMI reduction

Abstract: The need of high-speed printed circuit board design has increased in modern integrated circuitry while maintaining signal integrity and EMC standards as they became challenging issue. In this work, a high-speed PCB design which emitted high radiated emissions exceeding the EMC standard limits up to 4.54 GHz, has been fabricated and gone under radiated emission test. The EMI of the proposed PCB at 4.54 GHz has been suppressed using EBG spiral with patch planar that was integrated into the noisy PCB. Analyses of these characteristics indicate that the proposed EBG structures design is appropriate for the target EMI reduction.

Electromagnetic interference of CCTV

Abstract: All electronic and electrical devices generate interference signals that may effect on working other devices in the area. The paper describes a level of electromagnetic interference that IP cameras generate. The measurement must accomplish requirement according to the norm CSN EN 55022 ed.3.

Optimal design of EMI filters for PV system based on parasitic parameter and stability analysis

Abstract: Electromagnetic magnetic interference (EMI) issue has become one of the urgent problems to be solved in the photovoltaic (PV) inverter system Therefore, it should not be ignored In order to optimize the EMI filter design, high frequency characteristic of a PV system is studied in this paper A conducted EMI model is proposed The proposed model take into consider the influences of PV array parameters, DC side cable impedance, inverter parasitic capacitance and the unbalance of AC side impedance Based upon that model, a passive EMI filter used for the DC side of a PV system is designed and fabricated And the designing steps have been given thoroughly To acquire the best performance of the filter, a stabilization analysis based on Routh criterion is also made Finally, experimental results are presented to verify the efficient of the proposed EMI filter