This letter proposes a structure designed based on the Helmholtz coils for calibrating magnetic near-field probes. For the traditional calibration methods, the inherent position sensitivity issues of the probes, stemming from their physical structure, necessitate the procedures to be more complex. Therefore, designing a new probe calibration structure is necessary to obtain the accurate probe factor quickly. Utilizing Helmholtz coils, a rectangular calibration device has been designed to ensure a uniformly distributed magnetic field at its center plane to reduce the influence of the nonuniformity of the magnetic field on the probe factor. Finally, the calibration device is fabricated and tested, and the probe factors of the magnetic near-field probes are obtained. Upon comparison with the calibration data provided by the probe manufacturer, the probe factor obtained through the proposed calibration structure exhibits a high degree of consistency with the manufacturer's data. This indicates that the proposed structure can calibrate magnetic near-field probes within 1 MHz to 3 GHz, thus demonstrating its feasibility and accuracy during the calibrating procedure.

This article presents a Pearson's random walk approach for modelling the electromagnetic emissions of $N$ parallel connected power electronic converters. For the first time, a methodology that enables testing the random walk approach is presented. This methodology is validated in two ways: firstly, via simulations of a simplified setup consisting of 8 half-bridge power electronic converters. Secondly, it is validated with the use of an experimental setup consisting of 3 dc/dc converters. The verification is done in the complex domain, as well as by comparing the magnitude of the common mode current via the theoretical cumulative distribution function and the empirical cumulative distribution function. Finally, the probability of electromagnetic interference reduction at a specific harmonic of the switching frequency is derived.

The rapid development of more-electric transportation has led to increased use of higher voltage dc circuit architecture and battery storage. These developing technologies create a higher risk of dc arc failure resulting from component or insulation degradation. Arc faults present a risk to system reliably and safety, starting electrical fires that could prove catastrophic in transportation applications. To ensure ongoing passenger safety, the development of rapid dc arc fault detection methods is necessary. This article further develops the windowed fractal dimension (WFD) arc detection method for a range of linear and nonlinear loads, including networks containing switching power convertors. Results consistently show a substantial change in WFD at arc onset, and whilst the arc is sustained, for all load conditions. The outcome is a new method of fast dc arc detection requiring fewer calculation steps, fewer parameter settings, and reduced commissioning when compared to other arc detection methods, and can be used in tandem with existing protection schemes to provide a clear and robust indication of dc arc failure and prevent circuit damage.

The analysis of stochastic electromagnetic fields is gaining more and more relevance due to the exponential growth of complex high-performance electronic systems. Stochastic electromagnetic fields are characterized by auto and cross-correlation functions which can be obtained from experimental data. Different methods have been proposed for the numerical propagation of correlation information within the near-field region of a stochastic radiator. As a guideline for general geometries, near-field Green's functions combined with the method of moments can be used for the numerical estimation of field correlations in the near-field surrounding a device under test. In the ray-tracing limit, a more insightful propagation method based on the Wigner transformation has been devised, through which it is also possible to estimate the propagation of stochastic fields in the near-field. In this paper we report on the implementation of the proposed guide in the open source Python programming language, accessible through the IEEE Standard Association repository to ensure the dissemination of the standard and encourage the development of new versions.

A multilayer air-core inductor's operational frequency limit can be known beforehand if its first self-resonance frequency can be predicted. The self-resonance frequency is due to the electrostatic capacitance stored between the turns and layers of the inductor. This article presents an analytical technique to predict the first self-resonance frequency specifically for an ortho-cyclically wound multilayer air-core inductor through electrostatic field segregations. The static capacitances between the inductor's turns and layers are segregated into vertical and horizontal electrostatic field components, and are further aggregated to predict the first self-resonance frequency. Further, a multiobjective optimization technique using the pareto-optimal fronts through key parameter variations for inductor design is presented. The analytical technique is verified with acceptable results using prototype inductors. This analytical technique and optimization can be applied in designing ortho-cyclically wound multilayer air-core inductors for low and high frequency applications.

Reliable, repeatable, and flexible testing is crucial for assessing system performance and ensuring the quality of communication. In reverberation chambers (RC), real-life propagation environments can be emulated by loading absorbers, facilitating controlled testing of the system. This work presents over-the-air (OTA) testing of the LTE-A PHY layer in the RC. We assessed the performance of the LTE-A link using key performance indicators (KPIs) such as error vector magnitude (EVM), bit error rate (BER), and signal-to-noise ratio (SNR) for varying transmitter (Tx) and receiver (Rx) gains. Additionally, we have compared the results both in an empty RC and when the RC was loaded with RF absorbers. We used software-defined radio (SDR) for OTA transmission of LTE-A frames. The measurement results indicate that loading the RC with RF absorbers improves EVM, BER, and SNR. We also quantified the performance of the LTE-A link by changing the position of RF absorbers. Results showed that loading absorbers yielded up to 72.8% improvement in EVM, and placing absorbers closer to Rx helped reduce the amount of multipath, resulting in better transmission performance.

In this article, a line impedance stabilization network (LISN) with frequency bandwidth extended down to 2 kHz is designed, to address low-frequency measurement not currently aligned by the IEC and CISPR standards. For instance, different evaluation methods and limits are defined for the frequency range from 2 to 150 kHz in IEC 61000-4-7, IEC 61000-4-30, and CISPR 16-2-1. To this end, the limitations of existing LISNs for conducted emission (CE) measurement are first investigated, and a two-stage cascaded filter LISN topology is designed by resorting to multiobjective optimization. To ensure the desired performance, the influence of component tolerance and parasitic effects are studied. Eventually, an LISN prototype was manufactured and characterized. It was proven that the proposed LISN assures improved performance in terms of decoupling factor, voltage division factor, and LISN impedance in the frequency interval starting from 2 kHz.

Most current grid-connected strategies are grid-following converters (GFL), where the converter is designed to follow grid voltage and inject current into the grid. This method might not be the most satisfactory control strategy in recent years, particularly in low inertia and weak grids, due to possible interaction triggered by a phase-locked loop (PLL) during dynamics conditions. Therefore, a grid-forming converter (GFM) control mode was developed to allow the converter to emulate the characteristic of the synchronous machine as an ideal voltage source to support the grid's voltage, frequency, and grid stability during normal and fault conditions. This paper investigates the GFM converter's based Virtual Synchronous Machine (VSM) on Fault Ride Through (FRT) capability when symmetric and asymmetric faults are present on the grid. The proposed FRT approach for limiting the converter current uses indirect voltage control across the output of the filter inductor.

The aim of this paper is to explore a statistical approach to predict the distribution of the harmonics of common mode current in a setup consisting of N converters, knowing the common mode current for a single converter. To this end, we utilize Pearson’s random walk approach in comparison with a simulation setup consisting of 4 DC/DC converters with their own DC sources. The two methods, compared with respect to a selected harmonic of the common mode current, show good agreement up to 10MHz – 501st harmonic of the 20kHz switching frequency. The arising mismatch could be due to limitations of our model as well as to computational errors.

This paper presents a review of a number of techniques used for near-field scanning and detection of electromagnetic radiation sources. It also gives an overview of standards, related to technical requirements for the devices as well as scanning methods. Subsequently, a comparison between Far Field (FF) and Near Field (NF) is given. We present the advantages of NF over FF, and list the common problems for NF scanning, such as calibration, protraction in overall scanning time. Finally, we refer the possible solutions and improvements for scanning setup and software.

Electromagnetic Interference (EMI) is generated and mitigated in power converters. EMI problems are related to high-speed power converters. This article focuses on conducted electromagnetic interference in adjustable-speed drive (ASD) systems. The electromagnetic compatibility of three-phase/level grid-connected drive inverters is investigated. The test setup is built per the CISPR16-1-2 standard, and the interferences produced from the inverter to the grid are measured. The main dependencies of conducted emissions of a power inverter, changes in the length/shape of main cables, and motor speed have been investigated under load and no load conditions. Factors affecting EMI performance and filter design issues will be addressed. A statistical approach to quantifying the frequency domain impact of conducted emission noise created on the three-phase system by operating various emission sources. Fast Fourier Transform (FFT) was applied for time-frequency domain conversion, and to evaluate with a statistical approach Minitab software was used. Then, a filter design is created to prevent these interferences from being conducted to the grid. Also, the noise attenuation of the EMI filter has been validated in the simulation. Briefly, this study fills in the blanks of uncertainties involved in measuring three-phase emissions, which helps the engineers at the design stage of three-phase converters.

Electrification of aircraft, ships and rail has led to an increased use of DC power networks and at higher operating voltages. Arc faults in these higher voltage systems have increased energy levels and can potentially cause significant damage and destruction. These DC power systems are used across a wide range of environmental conditions, and there is a need to understand how the environment affects arc generation and arc detection. Experimental results indicate a clear difference in arc behaviour between humid and dry environments, suggesting a reduction in the transient features used for arc detection and an increased arc duration, resulting in a heightened risk as relative humidity decreases. Results also indicate a reduced response from arc detection algorithms from arcs in drier environments. This has highlighted the need for additional work regarding the change in arc characteristics with varying environmental conditions. and the impact this has on detection and power network protection.

Abstract In this work, near‐field and far‐field link measurement in metal enclosure environment is performed. The performance of near‐field and far‐field links are assessed using key performance indicators such as error vector magnitude, bit error rate, and signal‐to‐noise ratio. The metal enclosure is placed in an anechoic chamber, ensuring a stationary measurement environment. There are no external interference sources and the results are a function of near‐field and far‐field scenarios and hardware impairments. In measurements, software‐defined radios used for the transmission and reception of image data using the long‐term evolution‐advanced physical layer. Based on the results of the study, an optimum gain region can be determined where better key performance indicators are achieved. Furthermore, the frequency selectivity of the channel is reduced within the determined optimum gain region, leading to an improvement in the system's performance.

Arc faults, often caused by insulation or component failure, result in a discharge of electricity through the air between conductors. These failures are often the cause of electrical fires and pose an enhanced risk to system reliability, and this is becoming a growing problem with the uptake of more electric automotive and aircraft technologies. DC series arcs are of a particular concern as they do not trip existing circuit overcurrent protection. Arc detection is becoming increasingly difficult as DC voltages increase to meet the higher power demands of renewables, transport and series applications. This paper proposes a novel method to detect DC series arcs by monitoring the fractal dimension of the supply and load current and voltage waveforms. DC series arc faults were reproduced across a range of different setups using a 42V supply and a resistive-inductive load. The Windowed Fractal Dimension (WFD) method; implemented in MATLAB, shows a clear change in fractal dimension when an arc is sustained, providing both a means of arc fault detection and evidence that arcs have fractal properties.

Electrified railways have become increasingly important due to their efficiency, cost-effectiveness, and environmental benefits. Multiple power converters in AC railway systems are known to cause Electromagnetic Interference (EMI) issues, leading to potential system malfunctions. The objective of this paper is to provide a detailed insight into the electromagnetic interference modelling and validation methods in electrified railways. To realize this, a well-defined approach to investigate different modelling schemes is proposed, based on which the simulation and statistical analysis of the EM parasitic components impact on common-mode emissions is analysed. The insights provided in this study can be used to develop an organized understanding of EMI modelling and design effective mitigation strategies to reduce EMI in electrified railways.

Switched-mode power supplies (SMPSs) are utilized with fast-switching wide band-gap devices that operate at switching frequencies in the hundreds of kHz range and very short switching time. As a result of the wide spectrum, electromagnetic interference (EMI) is a critical issue for SMPS. The size and weight of power line filters can decrease as the frequency increases. Higher frequency, on the other hand, increases the generated EMI noise, so the size and cost of the required EMI filters are difficult to assess due to conflicting requirements for high power density applications. Conversely, as parasitic effects become more dominant in the high frequency range, increasing switching frequency may result in higher levels of high frequency EMI noise. Connecting multiple converters in the input and output ports have demonstrated their effectiveness in reducing EMI, such as interleaving, which connects in parallel for both ports. However, other configurations based on series and parallel at the two ports have not been addressed. This paper will address three different configurations for connecting two forward converters in comparison with single forward converter. Based on the simulation of three configurations, this paper shows that the CM noise is highly influenced by the input node parasitics.

In this paper, a comparison based on electromagnetic compatibility capability, electromagnetic interference susceptibility, signalling, and electrification systems of Great Britain and Ukraine's railway systems will be analyzed.

Air-core inductors are key components in power converters and measurement equipment. To optimally design inductors, their self-resonant frequency (SRF) as a result of inherent stray capacitance should be accurately estimated. This paper presents optimal design procedures for air-core inductors, considering constraints such as SRF and inductor volume. To this end, a methodology is proposed to estimate the variability of stray capacitances, accounting for various uncertainty factors. Specifically, for single-layer air-core inductors, an empirical expression is adopted and experimentally verified to provide better predictions compared to the commonly used physical-based approach. For multi-layer air-core inductors, an enhanced analytical approach based on the energy-conservation method is proposed, which considers the impact of five influence factors. Two key factors (the proximity effect and the variation of turn length) are investigated by FEM simulations and incorporated into the enhanced models. The other three factors (the effective permittivity of the wire insulation coating, the winding tightness, and the electric field path assumption) are taken into account as uncertainty factors, leading to statistical estimates of the stray capacitance and SRF. Finally, two samples are fabricated for single- and multi-layer air-core inductors, which agree well with the design specifications, proving the effectiveness of the proposed design methodology.

This letter deals with the research and comparative analyses of the traction power system and electromagnetic interference (EMI) in the return traction current on the railways of Ukraine, Europe, and the U.K. The spectral compositions of return traction current were evaluated experimentally. The main ideas of this letter are to determine possible EMI in the return traction current at the different traction systems of world railways and evaluate their influence on railway automatics. The following tasks were decided: comparing world power traction systems of railways and their automatics devices, estimating EMIs in the return traction current, and making conclusions for the future. The sources of external EMIs in the automatics and telecommunication circuits are very diverse: traction networks with harmonics and pulses, high-voltage power lines; lightning discharges, which have both dangerous and interfering effects under various conditions; and various industrial sources of electromagnetic fields (motors, generators, and welding units).

The double-ended impedance-based fault location technique (DEFLT) uses the wideband frequency content of the transient generated by the fault to determine the impedance from the point of measurement to the fault. This paper evaluates and develops the DEFLT experimentally for a Shipboard Power System (SPS) to determine its robustness to source impedance, the presence of interconnected loads ("tapped" loads) and tapped lines. Results demonstrate that the estimated impedance (and therefore distance to the fault) is influenced by the presence of tapped loads when the source impedance is large, or when the tapped load is comparable to the rated load of the system. Therefore, a scheme is proposed that compensates for any tapped load without requiring any additional measurements. Using the proposed scheme, the maximum error is significantly reduced from 92 to 13%. Simulation and experimental results show that a high accuracy for the estimated fault location can be achieved.