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Günümüzde modern binek araçlarda uzun ömür, küçük boyut ve yüksek enerji verimliliği avantajları nedeniyle aydınlatmada kullanılan geleneksel halojen ampullü teknolojilerin yerini Işık Yayan Diyotlar (LED) almaktadır. Otomotiv endüstrisinde LED'lerin sürülmesi için kullanılan elektronik devrelerin firmalar ve uluslararası standartlarca belirlenen aydınlatma ve elektromanyetik uyumluluk (EMC) regülasyonlarını sağlaması zorunludur. Aydınlatma zorunluluğu için gerilim ve akım kontrolü sağlayabilen anahtarlama modlu güç dönüştürücülerinin (SMPC) kullanımı yaygındır. EMC başarısı için ise elektromanyetik girişim (EMI) filtreleri sıklıkla devre tasarımlarına dahil edilmektedirler. EMC testleri yüksek maliyetli ve zaman alan süreçlerdir. Maliyeti azaltmak ve zaman kazanmak için testten önce baskılı devre kartlarındaki (PCB) sorunları belirlemek amacıyla tasarım mühendisleri benzetimlere başvurmaktadır. Bu tez çalışması kapsamında bir binek araca ait ön sis lambasının SMPC içeren LED sürücü modülü PCB’sinin elektriksel eşdeğer devre modeli oluşturulmuştur. Sonrasında Uluslararası Radyo Girişimi Özel Komitesi (CISPR) 25’te tanımlananan iletilen emisyon (CE) ve yayılan emisyon (RE) testleri benzetim programlarında analiz edilmiş ve deneysel olarak gerçeklenmiştir. EMI filtre olarak kullanılan yüzey montaj teknolojili (SMT) ferrit boncuğun (FB) endüktif davranışı sonucu kondansatörlerle oluşturabileceği rezonansların CE üzerindeki etkileri incelenmiştir. Bu amaçla sürücü modülü güç hattında FB’nin yer aldığı ve almadığı iki farklı devre konfigürasyonu oluşturulmuş, CE testleri benzetim programında analiz edilmiş ve deneysel olarak gerçeklenmiştir. Elde edilen ölçüm sonuçları MBN 10284-4 regülasyon limitleri baz alınarak karşılaştırılmıştır. Son olarak FB’nin RE üzerindeki etkisi incelenmiştir. Bu amaçla RE testi için iki ayrı devre konfigürasyonun benzetim programında modelleri oluşturulmuş, analiz edilmiş ve deneysel olarak gerçeklenmiştir. Elde edilen ölçüm sonuçları ECE R10 regülasyon limitleri baz alınarak karşılaştırılmıştır. Nowadays, Light Emitting Diodes (LEDs) are replacing the traditional technologies used in lighting in modern passenger vehicles due to the advantages of long life, smaller size, and higher energy efficiency. Electronic circuits used in the automotive industry to drive LEDs must comply with lighting and electromagnetic compatibility (EMC) regulations and international standards set by companies. The use of switched-mode power converters (SMPC), which can provide voltage and current control for lighting necessities, is common. For EMC success, electromagnetic interference (EMI) filters are often included in the circuit design. EMC tests are costly and time-consuming processes. To reduce cost and save time, design engineers use simulations to identify problems in printed circuit boards (PCBs) prior to testing. In this thesis, the electrical equivalent circuit model of the LED driver module PCB containing the SMPC of the front fog lamp of a passenger car has been created. Afterwards, conducted emission (CE) and radiated emission (RE) tests defined in International Special Committee on Radio Interference (CIPSR) 25 have been analyzed in simulation programs and applied experimentally. The effects of resonances that can be created with capacitors because of the inductive behavior of surface mount technology (SMT) ferrite bead (FB) used as an EMI filter on CE have been investigated. For this purpose, two different circuit configurations with and without FB in the power line of the driver module have been created, CE tests have been analyzed in the simulation program and experimentally implemented. Obtained measurement results have been compared based on MBN 10284-4 regulation limits. Finally, the effect of FB on RE has been investigated. For this purpose, two different circuit configurations have been created, RE tests have been analyzed in the simulation program and experimentally implemented. Obtained measurement results have been compared based on ECE R10 regulation limits.

A recent investigation explored a new measuring concept used in partial discharges (PD) measurements in gas insulated substations (GIS), consisting of a magnetic loop antenna. The sensor's frequency response was characterized up to some tens of MHz. This paper proposes an improved version of the sensor with an extended bandwidth (BW) one order of magnitude higher: a resonance, attributed to a common mode current in the mounting hole, is identified and eliminated employing ferrite beads in the feeder cables. Moreover, this publication proposes an electric circuit model that fully covers the transverse electromagnetic mode (TEM) frequency range in GIS. The electric model is compared against experimental measurements using a 1 GHz bandwidth testbench, giving accurate results. Two contributions are achieved in this research: an improved magnetic loop antenna with extended bandwidth and an accurate electric circuit model. This publication paves the way for further research on time resolution and signal postprocessing techniques for magnetic loop antennas in GIS.

Parasitic currents on the sheaths of the coaxial cables will deteriorate the performance of the antenna, so the choke structures are needed. While a-quarter-wavelength choke sheaths at VHF and UHF are very long, miniaturized ferrite-EBG composited choke structures are proposed. The ferrite refers to ferrite magnetic beads. Electromagnetic bandgap (EBG) element is consisted of multi-section metal tubes with length relatively shorter than a-quarter-wavelength. The integrated structures are formed by arranging EBG elements and beads alternately along the coaxial line. The proposed choke structures combine the wideband choke performance of the ferrite beads and the high efficiency of the EBG structures. Furthermore, due to the difficulty of the quantitative measurement of the choke structures in an open space, a measuring setup designed in a transmission line model is devised. The choking effects of the proposed structures can be characterized by the $\vert \text{S}_{21}\vert $ parameter of the measuring device, as the direction of the currents flowing on the sheaths of feeding cables are the same as that of the currents on the inner conductor of the measuring device. Meanwhile, choking bandwidth, efficiency and size of the ferrite-EBG composited choke structures are compared with that of EBG structures and beads. The influence of different numbers of the proposed structures is studied. A prototype is fabricated and measured. The overall size of the ferrite-EBG composited choke structures is $0.25\,\,\lambda _{\mathrm {L}} \times 0.024\,\,\lambda _{\mathrm {L}} \times 0.024\,\,\lambda _{\mathrm {L}}$ (415 mm $\times40$ mm $\times40$ mm) ( $\lambda _{\mathrm {L}}$ is the wavelength of the lower end of the operating frequency band). The measured choking band ( $\vert \text{S}_{21}\vert < -10$ dB) is in the region of 181–343 MHz.

Ferrite-bonded magnets have been extensively used in small brushless DC (BLDC) motors for low torque applications such as fans and pumps. In particular, some motors of them with ferrite-bonded magnets, frequently called as plastic magnets, do not have a rotor core in order to reduce manufacturing costs and inertia of the rotating part. Accordingly, the magnetization distribution of the bonded magnets has a polar anisotropic direction to secure more magnetic flux. As a result, the magnetization orientation of the magnets is highly significant to accurately predict the performances of the BLDC motors. This paper deals with the magnetization analysis of the polar anisotropic ferrite ring magnet applied to an outer rotor type BLDC motor. The motor is employed for an electric water pump, and its rotor including the impeller consists of only the ferrite-bonded magnet material and made by injection molding. Consequently, a magnetizing fixture and an impulse magnetizer are not used for the magnetization of the outer rotor type motor. Instead, samarium–cobalt (SmCo) magnets having a relatively high curie temperature are applied for generating magnetic field. Finally, this paper presents a process to determine the anisotropic orientations of a ferrite ring magnet by finite element method. In addition, the validity of the analysis method is verified by test results.

It has been shown previously that a symmetric antenna such as a dipole driven via a balun from a coaxial transmission line can be represented as a 3-terminal, 2-port network and that for vertically-polarized antennas operated near ground this network is asymmetric. An experimental approach for the determination of the values of the elements in this network representation has also previously been given. Although reasonably good agreement between simulation and experiment was obtained, the experimental procedure required three 1-port measurements and could not accommodate full error correction in the vector network analyzer (VNA) calibration. Therefore, we consider an alternative experimental approach for determining the network components of the 2-port antenna model. The new approach involves connecting both ports of the antenna simultaneously to the 2-port VNA via a dual coaxial cable and fully exploits the capabilities of a VNA including calibration and adapter removal. Both approaches are presented in detail and compared. Finally, the effect of ferrite choke beads on the coaxial feed transmission line on the equivalent network is investigated.

In this present work, an attempt has been made to do the comparative experimental and theoretical evaluation of two identical double slope solar still (2m×1mbasin area) of 15° top cover inclination...

GaN devices are developed rapidly in recent years, which makes it possible to produce power electronic converters with higher efficiency and higher power density. However, with the circuit parasitic parameters, large di/dt and dv/dt caused by the GaN devices' extremely fast switching can easily lead to voltage and current oscillations. This problem affects circuit stabilities and increases the difficulty of application with GaN devices. In this paper, oscillation problems will be explained by oscillator theory and an oscillation suppression method will be introduced. All the researches here are based on Cascode GaN devices. Considering all circuit parasitic parameters, negative conductance models of the GaN devices in the switching-on and switching-off process have been established according to oscillation mechanism analysis. And stability criteria of the GaN-based circuit have been derived which can well predict that whether the oscillations will happen and how will the oscillations last. Besides, the suppression method that placing a ferrite bead in power loop in series has been introduced based on the established model. Selection method is provided quantitively and suppression effect can be calculated. All the achievements of this research have been verified by simulations and experiments.

Elektromanyetik Uyumluluk (EMC) yaşamın her alanında önemli olduğu gibi otomotiv endüstrisinde de önem taşımaktadır. Önlemler alınmadığı takdirde elektromanyetik alanlardan etkilenen otomobillerde öngörülmesi zor olan kazalar olabilmektedir. Elektrik ile çalışan cihazlarda akımların oluşturduğu elektrik ve manyetik alanların birbirleri ile etkileşimi sonucunda ortaya çıkan girişimler çalışma kararlılığını etkileyebilir. Bu nedenle girişim kaynakları ve kurbanlar belirlenmeli, önlemler alınarak sistem kararlılığının korunması hedeflenmelidir. Tez çalışmasında otomotiv sinyal lambasına ait devre kartının oluşturabileceği elektromanyetik emisyonlar incelenmiştir. Girişim kaynağı olan devrenin tasarımında yapılan değişikliklerin emisyon seviyelerini etkilediği görülmüştür. İletim ve yayılım yoluyla yapılan emisyon ölçümleri ilk olarak tasarımda anahtarlama ve giriş kondansatörlerinin yer aldığı durum için gerçekleştirilmiştir. Sonrasında bu kondansatörlerin yer almadığı tasarım için ölçümler gerçekleştirilmiştir. Aynı ölçümler devrede bulunan ferrit ile direnç değişikliği yapılarak gerçekleştirilmiştir. Alınan sonuçlar birbirleri ile kıyaslanarak yorumlanmıştır. İletim yoluyla yapılan emisyon ölçümleri esnasında düşük frekans bölgesinde limitlere yaklaşıldığı görülmüştür. Devredeki gerilim düşürücü dönüştürücünün anahtarlama frekansı olan 200kHz’e yakın frekanslarında üst limitler ile farkın yaklaşık 10 dBuV’a düşmesi ile kritik seviyelere yaklaşılmıştır. Ferrit yerine direnç kullanılan devrede ise tüm frekans aralığında yaklaşık olarak 20dBuV zayıflama olduğu görülmüştür. Yayılım yoluyla yapılan emisyon ölçümlerinde sonuçların birbirlerine çok yakın olduğu görülmüştür. Anahtarlama kondansatörü bulunmayan devrenin 30MHz ile 40MHz aralığında, diğer devrelere göre 6dBuV bir zayıflama yaptığı ölçülmüştür. Alınan ölçümler sonucunda yayılım yollu girişimleri önlemek için anahtarlama kondansatörünün etkili olduğu, iletim yollu girişimleri önlemek için ise ferrit kullanımının etkili olduğu görülmüştür. Electromagnetic Compatibility (EMC) is important in all areas of life, as well as in the automotive industry. Accidents that are difficult to predict can occur as a result of a vehicle that we drive can be affected by electromagnetic fields. Interferences that occur as a result of the interaction of electric and magnetic fields created by currents in electrically operated devices can affect the operating stability. For this reason, sources of interference and victims should be determined and it should be aimed to prevent malfunctions by taking on-site measures.In thesis study, the electromagnetical emissions that can be created from an automotive signal lamp through the circuit board were examined. The effect of the lighting product which is a source of interference, on the emission values has been observed with the changes made in the circuit design. Radiated emission and conducted emission measurements were taken firstly with the switching and input capacitors in the circuit design. Then same measurements were taken without switching and input capacitors. Same emission measurements were made by changing the resistor with the ferrite bead in the circuit. The measurements were compared each other and reached to the conclusion.During the emission measurements made by conduction, was observed the limits were approached in the low frequency region. The difference decreased to approximately 10 dBuV with the upper limits at frequencies close to 200kHz, which is the switching frequency of the step-down converter in the circuit. Using resistor instead of ferrite In the circuit, it has been observed that there is an attenuation of approximately 20dBuV in the entire frequency range. The measurements made by radiated, showed close results with each other. It has been measured that the circuit without a switching capacitor has an attenuation of 6dBuV compared to other circuits in the range of 30 MHz to 40 MHz. As a result of the measurements, it has been seen that the capacitor is effective to prevent radiated interference, and ferrite bead is effective to prevent conduction interference. Consept EMC

A model for estimating the total eddy current losses in ring ferrite cores is proposed, which is based on a microstructure model of the electrical parameters of the material (conductivity and permittivity) and on the solution of the wave equations in the core. The presented model, combined with state-of-the-art estimation of the hysteresis losses, gives good agreement with the core loss measurements, over a wide range of frequencies (10–700 kHz)., IEEE Transactions on Magnetics, 58 (2), ISSN:0018-9464, ISSN:1941-0069

This paper presents the magnetic core characteristics of three magnetic materials at cryogenic temperature. Amorphous, nanocrystalline, and ferrite ring cores are tested at room temperature as well as 77 K under various operating frequencies. The core characteristics, including saturation flux density, permeability, and power loss are analyzed. The results show the core characteristic differences between the room and cryogenic temperatures as well as the performance differences among different magnetic materials, which will help optimize the high-frequency inductor design for cryogenic applications. Furthermore, the thermal shock test is performed to test the reliability of the cores. One ferrite core inductor and one nanocrystalline core inductor are built and tested in a 9 kW buck converter at cryogenic temperature.

Silicon carbide (SiC) junction field-effect transistor (JFET) based bi-directional switches (BDSs) have great potential in the construction of several power electronic circuits, including matrix converters, multi-level converters, solid state breakers, and so on. Parasitic oscillation in SiC JFET-based BDSs has direct impact on the stability and reliability of these circuits. Proper handling of parasitic oscillation becomes highly critical. This paper focuses on the parasitic oscillation suppression in SiC JFET-based BDSs. A parallel snubber capacitor or a series ferrite ring was often used to damp parasitic oscillation in switching circuits in the literature. However, conventionally, the snubber capacitance was obtained by time-consuming and labour-intensive trial-and-error methods. The main contribution of this study is to derive the simplified equivalent transient circuit of the SiC JFET-based BDS considering all parasitic elements and quantitatively define the reasonable range of the snubber capacitance. And the combined effect of the selected snubber capacitance and the selected ferrite ring is investigated. In the end, simulation and experimental results validate the effectiveness of the proposed method.

Experimental and theoretical evaluation of conventional solar still (CSS) and CSS augmented with permanent ferrite ring magnets (MSS) have been reported. Mathematical model proposed by Kumar & Tiwari has been used for the evaluation of internal heat transfer coefficients, internal efficiency, exergy efficiency, and exergy destruction. The average partial pressure difference between basin water and inner condensing cover surface for MSS has been found to be 77.99% higher than CSS when experiments were carried out for 13 h. The maximum value of evaporative heat transfer coefficient of MSS leads over the CSS by 28.65% at 13:00 h. The distillate yield recorded during the experimentation for MSS is 49.22% higher as compared to CSS. It seems that the magnetization of water has enhanced the overall internal efficiency and exergy efficiency of MSS over CSS by 49.17% and 110.26% respectively. In MSS the presence of permanent magnets has remarkably reduced the exergy destruction in the basin area. Augmentation of magnets with the CSS has significantly enhanced the distillate output of MSS. It has been found that the theoretical results obtained from Kumar & Tiwari numerical model are in good agreement with the experimental results obtained from CSS and MSS.

The issues of modeling the characteristics of ferrite bead materials used both individually and in electromagnetic compatibility filters are considered. The article proposes two approaches for obtaining mathematical models of the characteristics of the material of ferrite beads. The first approach consists in the mathematical representation of the considered characteristics by approximating the experimental curves for the corresponding values of field intensity. The second approach is to approximate the characteristics of the ferrite bead material for the corresponding values of frequency and field intensity. The authors have proposed regressors for constructing approximating functions for different ferrite materials. The resulting models have demonstrated high accuracy of agreement with the experimental values. Assessment of the accuracy of the constructed models using the coefficient of determination showed that it is in the range of 0.84-0.91 for various ferrite materials.

In the paper is analyzed the possibility of using an MnZn ferrite ring core for realization of integrated passive devices. The inductor and capacitor are made with the commercial ferrite cores 3F3 by the Feroxcube, as common volume for both components. Dimensions of the analyzed cores are 10/6/4 and 14/9/ 5 mm. On both cores, 10 wounds of litz copper wire are placed. Using a silver paste, top and bottom part of both cores are metalized, making a capacitor. The capacitance and inductance of this hybrid design are measured using the Impedance Analyzer HP4194A, in the frequency range from 10 kHz up to 1 MHz.

New measurement accuracy results are presented for a Standard Gain Horn in a profession-level system, the MVG Stargate 64. This system offers calibration options, and draws on the user’s knowledge to choose the most appropriate one. An ideal measurement in an ideally calibrated system should be perfectly repeatable and independent of the choice of calibration method, but the variations caused by real-world effects are of interest. The measurements include the use of a coaxial feed cable with a multitude of ferrite beads (to suppress any currents on the cable outer), and the cable with no beads, and with an optical fiber feed system for eliminating the scattering contribution of the measurement cable. We also compare patterns taken at different times and temperatures. The pattern comparison basis is the vector pattern correlation coefficient (inner product). The worst-case pattern variations appear to be related to the temperature variation of the system.

Circuit models of ferrite beads used for electromagnetic (EM) noise filtering are important for prediction and effective reduction of EM noise on power or signal lines. A methodology for impedance characterization and modeling of surface-mount ferrite beads is proposed in this article. The presented methodology combines series and shunt characterization methods to extract the equivalent circuit model of ferrite beads. The extracted models consist of frequency-independent elements and they are valid up to 1 GHz, to cover the bandwidth required by the EM compatibility standards for measurements of EM emissions. The values of the lumped elements of the extracted model are optimized to fit the measured impedance characteristics for each ferrite bead at bias current levels up to 5 A. Finally, the values of the lumped elements are parametrized with respect to the bias current from 0 to 5 A and the normalized error of the model compared to the measurements is calculated and found to be less than 10 $\boldsymbol{^{\mathrm{-3}}}$ .

Nonlinear transmission lines (NLTLs) have been studied for high-power RF generation with good prospects of applications in pulse radars for remote sensing (SARs) and disruption of communications in the battlefield, for instance. In this paper, two 30-section hybrid NLTLs built using nonlinear inductors and capacitors (2.2- and 10-nF barium titanate ceramic capacitors with 10- $\mu \text{H}$ ferrite bead inductors) will be described. For the test, the line is fed by a negative input pump pulse generated by a 1 kV discharge of a 0.75- $\mu \text{F}$ storage capacitor via a fast 50-ns switching system composed by an insulated gate bipolar transistor switch and its gate circuit driver. In the hybrid line tests, using 2.2-nF ceramic capacitors the maximum soliton generation packet obtained on the middle section had a frequency of the order of 33 MHz with voltage modulation depth (VMD) of around 700 V. For every single shot, approximately 10 RF cycles with small damping were noted. With the hybrid line using 10-nF ceramic capacitors the soliton generation obtained on the middle section reached a frequency of the order 10 MHz, and VMD of around 200 V. The main conclusion from this experiment is that hybrid lumped NLTLs may be used to achieve RF in megahertz range with higher VMD compared their counterparts (i.e., capacitive or inductive lines) because of their stronger nonlinearity with the use of both nonlinear elements.

Road lighting systems require a significant amount of electric energy. To compensate for the utilized energy, the concept of a nanogrid road lighting system is presented. A solar panel is installed on the top of a lighting pole to generate electric power. In this research, a photovoltaic simulator (PV simulator), which is used to simulate solar behavior such as current, voltage, and power based on temperature and solar irradiance levels, is employed to replace a solar panel. In the nanogrid system, grid-connected and stand-alone micro-inverters are employed to convert the electric power. The inverters comprise switching devices that can generate electromagnetic interference (EMI) when operating, which is harmful to the grid system and the electrical equipment. In general, EMI has been studied and reduced in electrical appliances, which only receive electric power. However, for the nanogrid system, which supplies electricity to the grid system, there is less study on the EMI topic because the usage is still not widespread. In the future, the nanogrid system will be widely used delivering high power directly into the electrical grid system. Therefore, the study and attenuation of EMI in the nanogrid system are very promising. Conducted emission (CE) is one form of EMI that flows through a cable connecting several appliances in the frequency range of 150 kHz to 30 MHz. CE of grid-connected and stand-alone micro-inverters have high levels in the low-frequency range between 150 kHz&ndash, 5 MHz and then decreases steadily. CE attenuation is important for this inverter in a solar power system. This research studies the effect of CE mitigation on the nanogrid system. The result is compared with the Comit&eacute, International Sp&eacute, cial des Perturbations Radio (CISPR) 14-1 standard. Finally, the passive EMI filter can reduce CE and meets the CISPR 14-1 standard.

A great interest has been devoted to the study of nonlinear transmission lines (NLTLs) for radio frequency (RF) generation since they have been used with great success in RF generation by producing a train of oscillatory waves along the line and at its output. There are two configurations of NLTLs. The first one is a dispersive line consisting of LC sections with nonlinear components, and the second one is a continuous ferrite loaded nondispersive line generally biased by an axial magnetic field, known as gyromagnetic line. In this paper, the focus of the study is on the second one, since gyromagnetic lines can operate in a broader frequency range (0.3–2.0 GHz) with higher conversion efficiency (20.0%) when compared to lumped NLTLs, generally limited up to 300 MHz with less than 10.0% of efficiency, because of their dielectric losses and stray impedances on line structure. Different models have been used along the years by several authors with different approaches to study the gyromagnetic phenomenon by means of numerical simulations based on analytical models to predict the precession movement of the electron magnetic dipole of the ferromagnetic material. Thus, the goal of this paper is to analyze the gyromagnetic NLTL behavior through the effects on the line operation. The novelty herein is to use two biases simultaneously to study continuous gyromagnetic NLTLs, focusing on the pulse rise time compression and RF generation caused by the precession of the magnetic dipole. An experimental setup is described and tested for low- and high-voltage operation for a 20-cm gyromagnetic line loaded with NiZn ferrite beads. The novelty of this paper is to use two biases simultaneously to study continuous gyromagnetic NLTLs, such techniques can be useful in the design of continuous lines for RF applications in space and mobile defense platforms of compact size.

Silicon carbide (SiC)-based junction field-effect transistor (JFET) bi-directional switches (BDSs) have great potential in the construction of many power electronic circuits, including matrix converters, multi-level converters, solid-state breakers, and cycloconverters. However, the oscillations of BDSs during turn-on and turn-off transition have great impacts on the stability and reliability of power electronic systems. Two methods are proposed to improve the switching performance, namely using a snubber capacitor and using a ferrite ring. It is found that the use of a snubber capacitor mainly improves the turn-off transition, and the use of a ferrite ring not only damps the oscillation of current waveform during turn-on transition but also makes the waveforms cleaner and less noisy. Besides, both methods can cut down settling time significantly. The effects have been demonstrated by theoretical analysis and verified by experimental results.

The electromagnetic interference of the motor drive system has a great influence on the performance. For the motor drive systems, the interference of CM current is important cause of conducted emission. AC side of motor drive system is high voltage and load is large inductive motor, so the AC side has a big impact on the DC side in the process of rapid on-off devices. The CM EMI current paths at frequency 30 MHz are analyzed based on the distribution parameters of elements in current flowing circuit. The change of the CM EMI current will be analyzed through circuit and equation of the CM EMI current when the AC cable is added ferrite chokes or ferrite. The DC conducted emission electromagnetic interference suppression effect is obvious to add ferrite chokes or ferrite the AC cable in high frequency in the experiment, which is consistent with theoretical analysis. The results show that adding ferrite is more effective measure than adding ferrite choke to suppress the DC side conduction emission electromagnetic interference both in decreasing amplitude and larger frequency band.

In the paper, an electromagnetic interference (EMI) model for a two-stage cascaded boost converter is presented to distinguish its noise sources. To illustrate the effects of switching speeds on EMI generation potential, the relationships between the time domain and the frequency domain with all-SiC and SiC–Si device combinations are provided. It is found that the voltage ripples and spikes at turn-OFF generate common mode (CM) noise in the high-frequency range, above the cutoff frequency determined by the short switching time of the SiC MOSFET. Several methods are presented for minimizing the noise sources using a ferrite bead and a modified gate driver. Experimental measurements of SiC switching waveforms and CM EMI taken from a 600-W prototype two-stage cascaded boost converter operating at 100 kHz are presented to validate the CM noise analysis.

Sensor antenna is an interesting concept for nondestructive testing. For example, we can observe the stats of reinforced concrete (RC) in buildings. However, if the concrete gets moisture by rain and so on, the quality of concrete will deteriorate. To avoid this, we have to regularly monitor the quality of the concrete. When a concrete gets wet, the resonant frequency of a sensor antenna having a probe in the concrete shifts lower. In this paper, the authors propose a sensing probe to be inserted into the concrete, which is used with an interfacing antenna on the concrete surface. The resonance frequency of proposed probe part changes from 0.98 GHz to 1.04 GHz.

A growing interest has been raising around the use of nonlinear transmission lines (NLTLs) for radiofrequency (RF) generation since recent results published has demonstrated great prospects for this application. The subject of this paper is about a continuous ferrite loaded nondispersive line known as a gyromagnetic nonlinear transmission line (GNLTL), biased by an axial magnetic field. This type of transmission line has demonstrated a high RF conversion efficiency (up to 20.0%), showing a good capability of operation in a broader frequency range, between 300 MHz and 6.0 GHz. Several authors used different approaches to study the gyromagnetic effect to understand the precession movement of the ferrite magnetic dipoles. The model proposed and studied here to analyze the GNLTL has a coaxial structure using NiZn ferrite beads distributed in a 20-cm coaxial line at a high voltage operation. Signal results were compared to check the influence of a solenoid on the axial magnetic bias. This paper explores the oscillations generated at the output caused by the changes in the magnetic system setup. It is expected that the discussion presented here will be useful as a basis to develop a new system capable of generating RF for mobile defense platforms.

This paper propose a model of complex magnetic permeability of ferrite core inductor with frequency independent lumped parameters. The electrical model, suitable for circuit design process, is consist of two resistance, one inductance, and one capacitance. The model with four unknown parameters is tested on ferrite ring core 3F3 10/6/4 by Ferroxcube. Impedance and core loss of the core are measured at low excitation up to 1 mT and in operating frequency range from 0.1 to 10 MHz. Two of these four parameters are obtained by measurement or taken from the data sheet. Remain two parameters are estimated by fitting procedure comparing equivalent serial representation with measured data. The measuring procedure is performed using an Impedance Analyzer HP 4194A.

A non-contact current measurement device comprised of a GMR sensor and a ferrite ring core was investigated. The sensor chip employed a high-sensitivity spin-valve full-bridge GMR sensor of which the direct output has non-negligible hysteresis and a limited linear range. By applying an AC modulation current to modulate the output of the GMR sensor, the hysteresis was reduced, and the linear range was over &plusmn, 0.5 A. The resolution for DC and quasi-static current measurement was 0.1 mA at a 10 Hz bandwidth. The output in proportion to the measured current was obtained either by demodulating the current-sensitive AC signal or by employing the filtered output of the intrinsically nonlinear spin-valve response. The proposed current sensing scheme is suitable for quasi-static current measurement from DC to over 100 Hz.

High power-density and high efficiency are the two driving forces for point-of-load (POL) converters used in portable electronics and other applications where system miniaturization is required. Discrete passive components, especially bulky inductors, have become the bottleneck for downsizing POL converters. Low-temperature sintered Ni-Cu-Zn ferrite tapes for multilayer chip inductors have been widely studied and used in high-frequency power electronics applications. In our previous study, a low-profile, planar inductor substrate with lateral flux pattern was fabricated using mixed commercial low-fire Ni-Cu-Zn ferrite tapes and compatible low temperature co-fired ceramic (LTCC) processing. However, thermal interface material was used between active circuit board and passive layer (ferrite substrate), which increases the total volume of the converter and becomes a potential threat for reliability due to the mismatch of coefficient of thermal expansion among different layers. Additionally, this hybrid integration method requires labor-intensive manual steps which are not compatible with cost-sensitive power electronics market. A fully ceramic-based POL module with integrated multilayer ferrite inductor has been proposed. The circuit and other components are designed to be directly built on top of the multilayer ferrite inductor substrate. This presented work focuses on the development of the multilayer ceramic substrate with embedded planar, lateral-flux inductor by co-firing of ferrite and dielectric tapes with conductor paste. Commercial dielectric LTCC and ferrite tapes were chosen for the fabrication of multilayer ferrite inductor substrate. Different silver pastes were co-fired with ceramic tapes to form the inductor winding. The sintering behavior and compatibility of dielectric, magnetic, and conductive components in one co-firing process was studied in order to realize a cohesive multilayer ceramic substrate. The embedded inductors present lower inductance than pure ferrite inductors sintered alone using the same profile when the output current is smaller than 10 A. The inductance of both types of inductors are very similar when output current is above 15 A. The inductor embedded in dielectric tapes exhibits higher core loss density than its counterpart. Future work will focus on the integration of high current POL module using this developed multilayer ferrite inductor substrate.

This paper presents a novel technique for suppressing cable noise currents, the quadruplet-resonator-based ferrite-free choke (QR-based FFC), to eliminate the gigahertz (GHz) electromagnetic interference caused by noise currents flowing on the cable shielding. This problem is difficult to handle with conventional ferrite materials since their permeabilities dramatically degrade when the operating frequency goes up to several GHz. In this paper, with the aid of QR surrounding on the cable shielding, the FFC forms bandstop responses against the noise currents. The corresponding equivalent lumped circuit model is proposed and investigated. Furthermore, the synthesis procedure is established using microwave filter theory. The QR-based FFC can achieve a high-level current suppression at the desired frequency band. This technology is experimentally verified: a given design example is demonstrated at the operating center frequency of 2.57 GHz. The frequency range of 3-dB current suppression is measured from 2.47 to 2.75 GHz (FBW $= $ 10.8%), where the highest suppression level is up to 36 dB. The FFC-added cable also demonstrates a good result in the reduction of far-field radiation, where the reduction level of radiation peak gain is measured as 7 dB compared with that of a bare cable.

Planar gigahertz (GHz) inductors were fabricated based on high crystalline-anisotropy Zn0.13Co0.04Ni0.63Fe2.2O4 (Zn-Co-Ni ferrite) and Ba3Co2Fe24O41 (Co2Z hexaferrite) and characterized for inductance (L) and quality (Q) factor. The planar ferrite inductors show an L of 4.5 nH (Zn-Co-Ni), 5.6 nH (Zn-Co-Ni + low Hk and fFMR Co2Z:), and 4.8 nH (Zn-Co-Ni + high Hk and fFMR Co2Z:) at 2GHz. The corresponding L-densities are 18.0, 22.4, and 19.2 nH/mm2, which are greater than 16.8 nH/mm2 of the air-core inductor. With respect to the Q factor, the air-core and ferrite inductors exhibit Q factors of 6.7 (air-core), 4.8 (Zn-Co-Ni), 2.8 (Zn-Co-Ni + low Hk Co2Z), and 4.0 (Zn-Co-Ni + high Hk Co2Z) at 2GHz. The tan δμ of the ferrites caused a reduction in the Q factor. Nevertheless, the high Hk and fFMR Co2Z ferrite inductor demonstrates a higher Q factor than that of the low Hk and fFMR Co2Z inductor. It is, therefore, suggested that high resistivity, anisotropy, magnetization ferrite can produce large L density and Q factor GHz inductors.

This paper introduces an improved electrostatic discharge (ESD) system-level transient simulation modeling method and discusses its validation using IEC 61000-4-2 ESD pulses on a real-world product. The system model is composed of high current and broadband (up to 3 GHz) models of R, L, C , ferrite beads, diodes, and integrated circuit IO pins. A complex return path model is the key to correctly model the system's response to the IEC excitation. The model includes energy-limited time-dependent IC damage models. A power–time integral method is introduced to accurately determine if a junction would experience thermal runaway under an arbitrary injection waveform. The proposed method does not require knowledge of the junction's microscopic geometry, material information, defect location, or melting temperature.

Field Induced Charged Board Events (FICBE) experiments were conducted. The waveforms were verified using charged device model (CDM) standards. The discharge probe was constructed to determine the electrostatic discharge sensitivity of a PCB. The standard CDM current waveforms were used as a reference to ensure proper function of the discharge probe. The investigation revealed that a lower impedance of a pogo pin improved the sensitivity. The parallelizing of a pair of 2 Ω resistors reduced the parasitic inductance. Inclusion of a ferrite bead on the current sensing wires reduced the common mode noise. This test bench complies with standard CDM current waveforms.

Magnetic immunostaining is a technique used to accelerate the antigen-antibody immunoreaction by increasing the local density of antibody on the surface of a tissue specimen using a magnetic field. The high density of antibody is achieved by applying a magnetic force to antibody-labeled ferrite beads toward the specimen. A technical challenge of using conventional magnets for this technique has been the inhomogeneous accumulation of magnetic beads on the specimen in accordance with the distribution of the magnetic field. Thus, in this study, a dome-shaped magnet that generated a strong and uniform magnetic force distribution was proposed and demonstrated. Numerical analysis was used to optimize the shape of the magnet. Analysis of the motion of magnetic beads showed that the accumulation of beads on the sample was complete within one minute and that the resulting homogeneity was sufficient for rapid and accurate immunostaining. Finally, experiments showed that the homogeneity of the bead distribution was improved by the use of a prototype dome-shaped magnet compared to conventional cylindrical magnets.Magnetic immunostaining is a technique used to accelerate the antigen-antibody immunoreaction by increasing the local density of antibody on the surface of a tissue specimen using a magnetic field. The high density of antibody is achieved by applying a magnetic force to antibody-labeled ferrite beads toward the specimen. A technical challenge of using conventional magnets for this technique has been the inhomogeneous accumulation of magnetic beads on the specimen in accordance with the distribution of the magnetic field. Thus, in this study, a dome-shaped magnet that generated a strong and uniform magnetic force distribution was proposed and demonstrated. Numerical analysis was used to optimize the shape of the magnet. Analysis of the motion of magnetic beads showed that the accumulation of beads on the sample was complete within one minute and that the resulting homogeneity was sufficient for rapid and accurate immunostaining. Finally, experiments showed that the homogeneity of the bead distribution was ...

The switching oscillations associated with the ultrafast switching characteristics of silicon carbide (SiC) MOSFETs seriously limit the potential of high frequency and high power density applications. To understand and mitigate this behavior, it is critical to analyze and compare different damping techniques for the oscillation suppression. This paper presents a simple RLC circuit model for SiC MOSFET turn-off switching oscillation, where the mitigation design guidelines are provided based on modeling analysis. The calculation, simulation and experimental results indicate that the switching oscillations can be properly controlled with the methods presented in this work. It is observed that the RC snubber and ferrite bead techniques offer more effective damping solution than the gate driver slowdown or extra gate resistor approaches.

Shielding of electronic devices is important for reasons ranging from regulatory to proper device functioning, and in applications from defense to consumer electronics. We report on the development and characterization of a novel microwave absorber material based on micron-sized ferrite beads and mm-length carbon fibers which are deposited electrostatically using the flocking process. The material is thin, lightweight, broadband and customizable with respect to frequency and amount of absorption. Absorber was characterized in X-band using NRL Arch Reflectivity measurements and it exhibited broadband attenuation ranging from around −10 dB at the edges of X-band to a peak of −46 dB at 11.1 GHz, which compares favorably with existing commercial solutions. Absorber permittivity and permeability were extracted using waveguide measurements for incorporation into EM simulations. It was determined that attenuation comes from both electric and magnetic field losses. Entire characterization process was verified by comparison with known absorber material and good agreement was found.

WiFi radio frequency interference (RFI) caused by a 5.76-GHz on-die clock is investigated. It is demonstrated that gigahertz on-die clocks that have no conductive connections to the package and board can introduce significant radio performance degradation to mobile devices. Conventional RFI mitigation approaches focus on megahertz and below GHz. The 5.76-GHz RFI noise mitigation solutions are investigated in package and board levels. The package solution utilizes self-resonance and minimum impedance characteristics of a capacitor in consideration of parasitic components of package. The board solution uses high-frequency ferrite bead that has high resistive and impedance properties at the frequency of the clock noise. The optimum characteristics of the 5.76-GHz filter components proved to provide> 10-dB RFI noise reduction. This work provides good understanding on gigahertz on-die noise propagation and mitigation guideline for designers to develop low-RFI platforms and also may help to debug/reduce such noise.

Silicon Carbide (SiC)-based Bi-Directional Switches (BDS) have great potential in the construction of several power electronic circuits including multi-level converters, solid-state breakers, matrix converters, HERIC (high efficient and reliable inverter concept) photovoltaic grid-connected inverters and so on. In this paper, two issues with the application of SiC-based BDSs, namely, unwanted turn-on and parasitic oscillation, are deeply investigated. To eliminate unwanted turn-on, it is proposed to add a capacitor (CX) paralleled at the signal input port of the driver IC (integrated circuit) and the capacitance range of CX is also analytically derived to guide the selection of CX. To mitigate parasitic oscillation, a combinational method, which combines a snubber capacitor (CJ) paralleled with the JFET (Junction Field Effect Transistor) and a ferrite ring connected in series with the power line, is proposed. It is verified that the use of CJ mainly improves the turn-off transient and the use of a ferrite ring damps the current oscillation during the turn-on transient significantly. The effects of the proposed methods have been demonstrated by theoretical analysis and verified by experimental results.

The paper is concerned with an equipment used to monitor power transformers. The equipment is working in an environment where electromagnetic interference may occur, being able to transmit data related to the transformers operation. The monitoring equipment was submitted to tests for conducted emissions. The initial tests revealed that the compliance with the norms from the standard related to conducted emissions for this type of equipment was not achieved. Several measures had to be taken to pass the tests. The first step was to reduce the conducted emissions associated to the inputs in the supplying source. Therefore a ferrite filter was designed and implemented, being placed at the equipment general supplying input. The conducted emissions were again evaluated and again the tests were failed. Consequently a network filter had to be designed and placed. Finally the compliance with the norms relative to conducted emissions was obtained.

The development of a novel microwave absorber material utilizing mm-length carbon fibers (CF) is reported. The CF are deposited electrostatically using the flocking process. Micron-sized ferrite beads are then deposited on tips of carbon fibers. The material is lightweight with density of ~0.32 g/in2and its thickness can vary from one to several millimeters. Its absorption is broadband and tunable with respect to frequency response and amount of absorption. The absorber was characterized in X-band using NRL arch measurement in an anechoic chamber. The material exhibited broadband attenuation ranging from around −10 dB at the edges of X-band to a peak of −46 dB at 11.1 GHz. Absorber complex permittivity and permeability were extracted using waveguide measurements. Electromagnetic simulations utilizing extracted parameters were compared with measured data and good agreement was found. Overall extraction process was successfully verified by comparison with a known commercial absorber material. The absorber performance compares favorably with existing solutions.

In this paper, vortex wave radiation from pseudo-traveling-wave ring resonators is demonstrated for the purpose of generation and tunable characteristics of orbital angular momentum (OAM) modes. The resonator is composed of nonreciprocal composite right/left handed transmission line on a normally magnetized ferrite ring. The numerical simulation and experimental results clearly show generation of multiple OAM modes with $l= \pmb{\pm 1}$ and $\pmb{\pm 2}$ , and tunable mode selection by changing the applied dc magnetic field.

This paper presents the diagnosis and mitigation of ESD failure due to internal digital clocks, in contrast to asynchronous/control signals conventionally. A combined simulation approach with 3D electromagnetic and circuit simulation is developed to capture the coupled ESD waveforms. It is validated with measurement data and good agreement is obtained. A filter comprised of a ferrite bead and shunt capacitor is demonstrated to improve the ESD robustness of a laptop system from 2 KV to 12 KV. This work may be employed to facilitate debugging of ESD issues and to improve ESD robustness.

In this paper, the noise propagation in power distribution network (PDN) of low-temperature co-fired ceramic (LTCC) based system-in-package (SiP) is studied, including the effects of printed circuit board (PCB) PDN. A low-pass filter for PDN noise isolation in LTCC-based SiP, which is made of discrete capacitors and embedded inductor, is proposed. This filter can be easily designed based on microwave-filter design theory. And it can provide broadband noise isolation along with PCB and package bulk capacitors. The electromagnetic full wave simulation results show that this method can provide noise isolation of 50dB from hundreds of kilohertz (KHz) to more than 10GHz in our case. Besides, this method can simplify PCB design by reducing ferrite beads and PCB decoupling capacitors.

Experiments were performed on two different ultra-high voltage gas-insulated switchgear test circuits to evaluate the mitigation performance of ferrite R2KB rings with very fast transient overvoltages (VFTOs). Significant decreases in the overshoot factor and the VFTO level were observed, although the steepness was not much improved owing to saturation. It was found that ferrite rings are more effective for VFTO mitigation at the source side than at the load side. Simulations were carried out with a new circuit model of the ferrite ring, and the simulation results were consistent with the experimental results. The method of drawing the contour plot of VFTO and very fast transient current in the time-space domain was proposed to facilitate the analysis. With this method, the principle of determining the optimal installation location of ferrite rings for the best mitigation performance was clarified.

Traditionally, ferrite-based tunable filters are biased by large and bulky electromagnets, which require high currents to overcome the dissipated fields at the air interface between the electromagnet and the ferrite substrate. This problem has been solved by implementing the windings inside the package using ferrite low-temperature co-fired ceramic (LTCC). However, these embedded windings, which are densely packed, generate heat that affects the characteristics of the ferrite material. In this paper, we investigated the heat effects due to embedded windings in ferrite LTCC filters. We also incorporated the heating effects into an electromagnetic simulation model and achieved a good agreement between the simulations and the measurements. We found that increasing the temperature of the filter module from 0 °C to 190 °C by external heating causes the center frequency of the filter to shift by about 1 GHz. Alternatively, when a dc current is passed through the bias windings, heat is generated in the windings to a temperature of 250 °C measured at 260 mA of current. This heat causes the tunability of the filter to increase by more than 2%.

Department of Information & Communication Engineering, Kyungsung University, Busan 608-736, Korea(Received 6 February 2015, Received in final form 16 February 2015, Accepted 16 February 2015)In this paper, a magneto-inductive wave generated in a chain of LC resonators fabricated with Ni-Zn ferrite cores and chipcapacitors is presented. RF signal propagates to neighbor resonator one by one as a consequence of the magnetical coupling betweentwo resonators in the device. The magnetical coupling is due to the mutual inductances along the chain of resonators. So, the signalamplitude (≈ coupling intensity) is dependent of the mutual inductance which can be adjusted by applied magnetic field. In order todemonstrate the device, some experiments have been carried out systemically. The transmission characteristics of a magneto-inductivewave could be controlled by applied external magnetic field. The device composed of 5 resonators; the center frequencies wereestimated to be 32 MHz and 38 MHz with the external magnetic flux density of 75 Oe and 222 Oe, respectively. We expect that thereported results could open a promising way to a high variety of applications in one- and two-dimensional functional devices, such astransducers, delay lines, power dividers and couplers.Keywords: magneto-inductive wave, ferrite core, periodic chain

With the deep and promotion of unattended work in substations, the correct rate of remote signal becomes an important index in automation scheduling system. For remote signal false caused by high-frequency interferences in substation, we propose the use of Ni-Zn ferrite ring to suppress high-frequency interferences. The frequency-impedance characteristics of ferrite ring with different turns are tested. And the inhibitory effect of ferrite ring on interferences below and above 100MHz is measured separately. We installed ferrite rings in remote signal loops, and compared the voltage waveforms before and after installation. Experimental results provide some references to suppress high-frequency interferences by Ni-Zn ferrite ring.

Ferrite beads are ferromagnetic materials that exhibit a small inductance at low frequencies, becoming resistive at high frequencies. These devices are used as low pass filters for reducing electromagnetic interference (EMI) in communications and power electronics because the resistive losses attenuate the undesired frequencies. As ferrite beads have a nonlinear behavior with current and frequency they have been used in nonlinear transmission lines (NLTLs) for high power microwave generation in space and defense applications. In this work, high frequency ferrite beads are characterized in the frequency range up to 1 GHz by measuring S11 reflection parameter in order to calculate their complex permeability and losses, key parameters in the design of NLTLs. In addition, X-ray diffraction (XRD) is used to identify their chemical element composition. Finally, the motivation for this work is basically due to the limited information on ferrite materials provided by the manufacturers.

Ferrite chokes are often applied to suppress electromagnetic interference (EMI) in power converters. In this paper, an improved ferrite choke RLC model and its parameters determination method are proposed. The improved ferrite choke RLC model can overcome the limitation of the existing RLC model in the low frequency band, and the proposed parameters determination method can calculate the values of RLC parameters more accurate according to curve fitting of the ferrite choke datasheet. The effectiveness of the improved ferrite choke RLC model is verified by simulation based on a PWM rectifier, and the accuracy of the parameters determination method is verified by the impedance fitting results. The proposed ferrite choke RLC model and parameters determination method in this paper can provide ferrite choke choosing guidance for power converters in engineering application.