Electromagnetic Interference Suppression Research Articles

Investigation of Some Magnetic and Thermal Properties of $$\hbox {Epoxy/Ni}_{0.5}\hbox {Zn}_{0.5}\hbox {Fe}_{2}\hbox {O}_{4}$$ Epoxy/Ni 0.5 Zn 0.5 Fe 2 O 4 Composites

Nanoparticles of \(\hbox {Ni}_{0.5}\hbox {Zn}_{0.5}\hbox {Fe}_{2}\hbox {O}_{4}\) have been prepared by the co-precipitation method, and X-ray diffraction analysis has confirmed the formation of the desired ferrite. A pure epoxy sample and three samples of \(\hbox {epoxy/Ni}_{0.5}\hbox {Zn}_{0.5}\hbox {Fe}_{2}\hbox {O}_{4}\) composites have also been prepared with different ferrite percentages. These samples have been characterized by Fourier transform infrared spectroscopy. The magnetization of the composites has been investigated by using a vibrating sample magnetometer and has revealed that these composites may be promising candidates for electromagnetic interference suppression. Moreover, the thermal diffusivity and thermal effusivity of epoxy and composite samples have been measured by using the photoacoustic technique, where a high enhancement of the thermal diffusivity with increasing ferrite content has been observed which can be attributed to the higher number of phonon vibrational modes as well as the longer mean free path of the ferrite nanoparticles due to their crystalline structure as compared to the amorphous structure of epoxy. Moreover, the formation of a percolated network of NiZn ferrite nanoparticles inside the epoxy may enhance the phonon conduction, increasing the value of the thermal diffusivity in the bulk of the samples. On the other hand, the almost constant values of the thermal effusivity—which is a surface property—suggest that these composites may be used not only for electromagnetic interference suppression but also for thermal shielding in electronic circuits.

The synergy of QFD and TRIZ for solving EMC problems in electrical products – a case study for the Notebook PC

This paper studies the design analysis and debugging mechanism against electrical product electromagnetic compatibility (EMC). The aim is to employ an effective electromagnetic interference suppression solution based on the integration of quality function deployment (QFD) and TRIZ during the early development phase of electronic products to reduce both unit cost and launch time. The QFD relationship matrix displays potential contradictions in technical requirements, and the TRIZ contradiction matrix methodology helps to suggest generic solutions which then serve as solution triggers. This paper takes the example of reducing a Notebook PC’s EMC to meet customer specification demands and with QFD applications. It then proposes an innovative approach in solving EMC contradictions including: (1) QFD-based case analysis for Notebook PC computer products, (2) key EMC issues derived out of QFD analysis, (3) innovative design solutions solving EMC issues by way of TRIZ, and (4) evaluation of multiple solution effectiveness.

Optimization of Modulation Waveforms for Improved EMI Attenuation in Switching Frequency Modulated Power Converters

Electromagnetic interference (EMI) is one of the major problems of switching power converters. This paper is devoted to switching frequency modulation used for conducted EMI suppression in switching power converters. Comprehensive theoretical analysis of switching power converter conducted EMI spectrum and EMI attenuation due the use of traditional ramp and multislope ramp modulation waveforms is presented. Expressions to calculate EMI spectrum and attenuation are derived. Optimization procedure of the multislope ramp modulation waveform is proposed to get maximum benefits from switching frequency modulation for EMI reduction. Experimental verification is also performed to prove that the optimized multislope ramp modulation waveform is very useful solution for effective EMI reduction in switching power converters.

Simultaneous Switching Noise Enabler in High-Speed Biomedical Systems by Integrated Plane Coupling

The performance of high-speed biomedical systems is adversely affected by switching noise caused by inductance in the power supply distribution network. In a high-speed medical system, signals are switched at rates up to 5 Gbps and discrete capacitors are ineffective in reducing the noise at this rate. The noise may affect patient care. Integrated plane coupling effectively minimized simultaneous switching noise by creating high capacitance between the planes. Although the suppression of electromagnetic interference due to switching noise on the component and printed circuit board is difficult, the integrated plane coupling at the front-end of the design cycle was shown to eliminate noise. The effect of switching noise coupling was investigated and a solution is reported. A test board was analyzed and the results were compared with simulations. This approach was shown to be effective in minimizing switching noise in high-speed biomedical systems.

Shaping High-Power IGBT Switching Transitions by Active Voltage Control for Reduced EMI Generation

High-performance power switching devices [insulated-gate bipolar transistors (IGBTs)] realize high-performance power converters. Unfortunately, with a high switching speed of the IGBT-freewheel diode chopper cell, the circuit becomes intrinsic sources of high-level electromagnetic interference (EMI). Therefore, costly EMI filters or shielding is normally demanded on the load and supply sides. An S-shaped voltage transient with a high-order time derivative eliminates the discontinuity in the switching transient and can suppress high-frequency spectrum of EMI emissions. More importantly, it provides an improved tradeoff between EMI generation and switching time, therefore switching losses. This promising tradeoff can be explored further for better high-frequency EMI suppression by using the infinitely differentiable characteristics of Gaussian S-shaped transients. However, current gate drive schemes cannot achieve the S shaping. In this paper, active voltage control is applied and improved successfully to define IGBT switching dynamics with a smoothed Gaussian waveform.

An improved control technique of switching frequency modulated power factor correctors for low THD and high power factor

This paper deals with switching-frequency modulation (SFM) for conducted electromagnetic interference (EMI) suppression in active power factor correctors (PFCs) operating in discontinuous conduction mode (DCM). The effect of SFM on different performance characteristics of DCM PFC is studied in details. It is shown that the use of SFM in PFC with conventional control approach leads to significant increase in total harmonic distortion (THD) and harmonic content of input current. Moreover, SFM leads to noticeable increase in peak power components currents. In order to use SFM for EMI reduction more effectively without significantly worsening THD, power factor, and harmonic content of DCM PFC, an improved control technique and a control circuit are proposed and verified by simulations and experimentally. The technique is based on the use of specific time delay injection to power MOSFET control signal. As show simulations and experiments, SFM PFC with the proposed delay technique in comparison to PFC without SFM has noticeably lower conducted EMI and THD of input current, at the cost of slightly decreased efficiency and moderately increased peak currents.

Growth behavior and RF/microwave properties of low temperature spin-sprayed NiZn ferrite

In our experiment, the influence of growth parameters of the spin-spray technique upon the microstructure and magnetic/microwave properties of NiZn spinel ferrite thin film was studied. By varying the pH value of precursor and oxidizer, the microstructure of NiZn ferrite thin film can be manipulated, further, bringing varying magnetic/microwave properties. High permeability μr′ > 200 at 0.5 GHz with low loss tanδm ~0.027 at 3–5 GHz range was achieved at precursor pH value of 4.6 and oxidizer pH value of 9.6. These magnetic/microwave properties are ideal for GHz range microwave application, for example, inductors, antennas, and electromagnetic interference suppression.

Suppressing EMI in Power Converters via Chaotic SPWM Control Based on Spectrum Analysis Approach

This paper aims at developing a spectrum analysis approach for suppressing the electromagnetic interference (EMI) in power converters via chaotic sinusoidal pulse width modulation (CSPWM) control signals based on double Fourier series. In detail, we prove that the total harmonics of power converters under CSPWM control are the same with those of power converters under traditional SPWM control. Then, we introduce a novel spectrum analysis approach based on sawtooth carrier and double Fourier series. Moreover, a photovoltaic (PV) inverter is used to validate the proposed spectrum analysis approach based on the calculation of the output voltage spectrum for CSPWM control signals. In particular, this proposed method can also be used for the spectrum analysis of multiperiodic signals. Indeed, this developed spectrum analysis approach provides a rigorous theoretical foundation for the CSPWM control in EMI suppression.

An Improved Layout Strategy for Common-Mode EMI Suppression Applicable to High-Frequency Planar Transformers in High-Power DC/DC Converters Used for Electric Vehicles

Presently, there is an immense impetus in the automotive industry to develop plug-in electric vehicles (PIEVs) to reverse the ever increasing green house gas emissions from fossil fuels and depleting fossil fuel resources. High-frequency ac-dc converters with an isolated output are one of the essential building blocks for transferring power from utility mains to the traction battery packs which store energy for propelling the EV. Generally, the ac/dc converters used in EVs include a PFC stage at the input side and an isolated dc/dc converter at the battery side. Due to the switching nature of the converter, electromagnetic compatibility (EMC) of these converters is an essential requirement, to ensure not only its own operation but also the safe and secure operation of surrounding electrical equipment. EVs possess a lot of sophisticated electronic circuits in the vicinity of the battery charging power converters. Thus, strict EMC standards of the on-board power converters must be met according to the CISPR 12 or SAEJ551/5 relevant EMC standards. Conventional passive filters used for EMI mitigation in power converters, comes at the expense of cost, size and weight, power losses, and printed circuit board real estate. In this paper, an electromagnetic interference (EMI) filter embedded into the main high-frequency planar transformer used in the dc/dc converter is proposed as a very cost-effective and efficient solution for EVs. The proposed structure is able to significantly suppress the common-mode (CM) EMI noise generated in the dc/dc converter. Experimental results have been obtained from a 3-kW prototype in order to prove the feasibility and performance of the proposed EMI filter. The results show that the proposed embedded EMI filter can effectively suppress the CM noise particularly for high switching frequency power converters. The proposed structure can be a very simple and cost-effective EMI filtering solution for future PIEVs.

An FPGA Chaos-Based PWM Technique Combined with Simple Passive Filter for Effective EMI Spectral Peak Reduction in DC-DC Converter

A new and simple but effective electromagnetic interference suppression technique based on field programmable logic array (FPGA) technology to provide a significant EMI noise attenuation in DC-DC converters is discussed. The voltage controlled boost converter for EMI reduction is analyzed using FFT under traditional PWM technique and chaotic mode operation. This technique aids the DC-DC converters to comply in specified EMI limits and replace conventional bulky passive filter with a simple passive filter. A prototype model has been tested and hardware results show significant reduction of EMI in chaotic mode operation of the boost converter.

Electromagnetic absorbing properties of graphene–polymer composite shields

A graphene-based composite, consisting of a thermosetting polymeric matrix filled with multilayer graphene microsheets (MLGs), is developed for application in thin radar absorbing materials. An innovative simulation model is proposed for the calculation of the effective permittivity and electrical conductivity of the composite, and used for the electromagnetic design of thin radar absorbing screens. The model takes into account the effects of the MLG morphology and of the fabrication process on the effective electromagnetic properties of the composite. Experimental tests demonstrate the validity of the proposed approach and the accuracy of the developed simulation models, which allow to understand the interaction mechanism between the incident electromagnetic field radiation and the MLG-based composite. Two dielectric Salisbury screen prototypes with resonant frequency at 12GHz or 12.5GHz and total thickness of 1.8mm and 1.7mm, respectively, are fabricated and tested. The results and technique proposed represent a simple and effective approach to produce thin absorbing screens for application in stealth technology or electromagnetic interference suppression.

Effective Suppression of Conducted Electro Magnetic Interference in DC-DC Boost Converter Using Field Programmable Gate Array Based Chaotic Pulse Width Modulation Switching

—In recent years, electro-magnetic interference on DC-DC converters is seen as serious problem as it limits the capability of the DC-DC converter. It is popular to use analog circuits to suppress electro-magnetic interference; however, a cheap analog circuit suffers from numerous drawbacks, including inaccurate pulse generation, carrier frequency limitation, and degraded performance due to aging. Conversely, high-performance digital circuits are capable of providing accurate pulses compared to analog circuits. In this article, a field-programmable gate array is used to generate accurate chaotic pulse-width modulation pulses for DC-DC converters. A spread spectrum technique based on randomized carrier frequency modulation with fixed duty ratio is proposed for gating pulse generation, implemented using a field-programmable gate array for electro-magnetic interference suppression. A hardware prototype is built in the laboratory for the proposed method and tested. The performance of the proposed method estimated through simulation study is validated via experimental results.

EMI Suppression in High Frequency Half Bridge Converter

Electromagnetic effects influence the design of power converters switching in MHz frequency region. In these converters, the high switching frequency in combination with sudden changes in current and voltage levels generate higher order harmonics which causes Electro Magnetic Interference (EMI). To study the effects of increased switching frequency on conducted EMI, the harmonics amplitudes are analyzed by increasing the switching frequency of a two wire input half bridge power converter from 1.32 MHz to 3 MHz. In order to suppress the Common Mode (CM) conducted EMI, different possibilities of connecting the Y - capacitor in a two wire universal input half bridge converter are discussed and the conducted EMI is measured and analyzed by connecting the Y - capacitor at different points. The line filters are designed, characterized and implemented in order to suppress conducted EMI. The effects of increased switching frequency on the line filter design are studied by analysing the EMI spectrum of both the converters. The analysis of results indicates that the filter size is reduced by increasing the switching frequency of the power converter. DOI: http://dx.doi.org/10.5755/j01.eee.19.9.5653

Study of Blind Source Separation on Transmission Line EMI

The transmission line is an important part of electrical system. Electromagnetic interference (EMI) signals can be picked up by transmission lines in a way of conduction or radiation, and interfere the sensitive devices located in the power source end and the load end, so it is important and necessary to separate and identify the EMI source signals coupling to the transmission lines in order to guide the electromagnetic compatibility (EMC) design and the further EMI diagnosis and suppression. Fast independent component analysis (FastICA) algorithm is studied and programmed, and its feasibility and separation performance are validated via simulation of BSS of three mixed signals and the average signals to interference ratio (SIR) is approximately 30 dB. The model of crosstalk of transmission lines is built and simulated, the interference signals are separated by the FastICA algorithm, and the average SIR is over 20 dB. Periodicity and spectral characteristics of the separated interference signals are analyzed, and the identification of interference signals is realized.

Novel Techniques to Suppress the Common-Mode EMI Noise Caused by Transformer Parasitic Capacitances in DC–DC Converters

This paper proposes novel electromagnetic interference (EMI) suppression techniques for dc-dc converters. For low-voltage high-current applications, windings are paralleled and interleaved. Although low conduction loss and low leakage inductance can be achieved, the winding capacitances are considerably increased, thereby deteriorating the converter's EMI and soft-switching performances. To solve these problems, a novel balanced choke concept is proposed, as well as other techniques. The advantages of the proposed concepts and strategies are verified and demonstrated on a 1-kW 1-MHz 400-V/12-V LLC resonant converter prototype. More than 52-dB noise attenuation and 75% equivalent winding capacitance reduction are achieved. Hence, EMI and soft-switching performances are significantly improved.

Electromagnetic Interference Testing and Suppression Methods for Automotive Window Lifter Motor

Window lifter motor is one of the potential electromagnetic interference (EMI) sources in automobile. Based on the research on the principle of Window lifter motor and the generation mechanism of EMI, its EMI characteristics are tested and analyzed. The EMI suppression methods are proposed. By comparing two filters methods,it shows that the designed filter suppresses the electromagnetic interference more effectively. Its conducted emission and radiated emission are lower than the second lever limits of CISPR 25-2007+.

ChemInform Abstract: Novel Applications of Ferrites

AbstractReview: 60 refs.

Microwave Absorption of Substituted M-type Lead Hexaferrite Nanopowders

M-type lead hexaferrites with compositions of PbFe12O19 and PbSnZnFe10O19 were synthesized by the citrate sol–gel method. The structural and magnetic properties of resultant particles were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer. The magnetic properties such as saturation magnetization (Ms) and coercivity (Hc) were calculated from the hysteresis loops. Microwave absorption properties of ferrite–polymer composites prepared with different ferrite ratios of 50%, 60%, 70% and 80% have been investigated in the frequency range of 12–20 GHz. The composite powder with 80 wt% lead ferrite possesses good microwave absorption properties. The minimum reflection loss of the composite powder reaches –30 dB at the thickness of 2 mm for composite powder with 80 wt% ferrite. The composite with 80% ferrite content has shown a minimum reflection loss of -24.5 dB at 18.6GHz with the -15 dB bandwidth over the extended frequency range of 16.3– 19.4GHz for an absorber thickness of 1.8 mm. The prepared composites can fruitfully be utilized for suppression of electromagnetic interference (EMI) and reduction of radar signatures (stealth technology). Keywords: Lead hexaferrite, nano-crystalline materials, microwave absorption, magnetic properties.

Application and Stability Analysis of a Novel Digital Active EMI Filter Used in a Grid-Tied PV Microinverter Module

This paper presents a novel technique to suppress common-mode electromagnetic interference (EMI) using a digital active EMI filter (DAEF). The DAEF control technique is concurrently implemented with a digital controller of a grid-tied photovoltaic microinverter. A brief description of the microinverter architecture and its inverter circuit is illustrated. The inverter stability is investigated using the overall transfer function. Accordingly, the system compensation is designed based on the direct quadrant (DQ) reference frame control technique. Finally, the proposed digital controller is tested on a grid-connected 200-W dc-ac microinverter. The experiment results validate the effectiveness of the proposed technique. Compared with the conventional passive EMI filter, the proposed digital controller can achieve an equivalent or better performance in terms of EMI suppression and maintain stability within the operation bandwidth. Therefore, the embedded DAEF can significantly reduce the size, cost, and space of the overall power inverter printed circuit board without the need of a conventional passive EMI filter.

The application of chaotic PWM control for EMI suppression

Purpose – Four‐quadrant AC‐DC converters are one kind of the most common and popular AC‐DC converters, which are serious EMI sources. The purpose of this paper is to propose a novel control for four‐quadrant AC‐DC converters to suppress the generated electromagnetic interference (EMI).Design/methodology/approach – A chaotic carrier plays an important role to implement the chaotic PWM control. The relationship between the EMI distribution and carrier frequency is given by deducing and analyzing the harmonic components of the AC‐DC converter. The comparison of chaotic PWM control and random PWM control in suppressing EMI are provided.Findings – The simulation results prove the effectiveness of the proposed chaotic PWM control on EMI reduction.Research limitations/implications – The effects of EMI suppression under different chaotic carriers will be theoretically analyzed in the future work.Practical implications – The proposed chaotic PWM control can suppress EMI for converters without adding additional dev...