Electromagnetic Interference Characteristics Research Articles

Robust EMI elimination for RF shielding-free MRI through deep learning direct MR signal prediction.

To develop a new electromagnetic interference (EMI) elimination strategy for RF shielding-free MRI via active EMI sensing and deep learning direct MR signal prediction (Deep-DSP). Deep-DSP is proposed to directly predict EMI-free MR signals. During scanning, MRI receive coil and EMI sensing coils simultaneously sample data within two windows (i.e., for MR data and EMI characterization data acquisition, respectively). Afterward, a residual U-Net model is trained using synthetic MRI receive coil data and EMI sensing coil data acquired during EMI signal characterization window, to predict EMI-free MR signals from signals acquired by MRI receive and EMI sensing coils. The trained model is then used to directly predict EMI-free MR signals from data acquired by MRI receive and sensing coils during the MR signal-acquisition window. This strategy was evaluated on an ultralow-field 0.055T brain MRI scanner without any RF shielding and a 1.5T whole-body scanner with incomplete RF shielding. Deep-DSP accurately predicted EMI-free MR signals in presence of strong EMI. It outperformed recently developed EDITER and convolutional neural network methods, yielding better EMI elimination and enabling use of few EMI sensing coils. Furthermore, it could work well without dedicated EMI characterization data. Deep-DSP presents an effective EMI elimination strategy that outperforms existing methods, advancing toward truly portable and patient-friendly MRI. It exploits electromagnetic coupling between MRI receive and EMI sensing coils as well as typical MR signal characteristics. Despite its deep learning nature, Deep-DSP framework is computationally simple and efficient.

The evaluation of EMI characteristics of 4G-IMT system on FAST around its RQZ

Mobile communication base stations have become ubiquitous with the popularization and development of mobile communication services. Although the Chinese government has designated a radio quiet zone (RQZ) specifically for Five-hundred-meter Aperture Spherical radio Telescope (FAST), the 4G International Mobile Telecommunications (4G-IMT) system is still heavily used to meet the communication needs around the RQZ. To assess the Electromagnetic Interference (EMI) caused by 4G-IMT base stations on the performance of FAST, this paper employs the International Telecommunication Union (ITU) deterministic radio wave propagation prediction model. The interference of 4G-IMT base stations on FAST is evaluated based on relevant parameters, such as the frequency used by both FAST and the base station, in conjunction with the FAST threshold protection requirements. The results indicate that 47.73 % of the data exceed the radio astronomy protection threshold of FAST. In addition, a field experiment was conducted to verify the accuracy of the radio wave propagation prediction method used. The root-mean-square error between the predicted value and the measured value was found to be 6.94 dB, supporting the accuracy of the predicted results. The findings of this study can help suppress interference from mobile communication services around the RQZ of FAST and optimize the electromagnetic environment around FAST.

Analysis of IGBT Pseudodesaturation Effect Caused by Stray Parameters in DC Circuit Breaker

As a highly integrated high-voltage power electronic equipment in the power grid, the DC circuit breaker (DCCB) has misjudged overcurrent protection caused by the IGBT pseudo desaturation effect (PDE) in DC short-circuit fault. To analyze the reasons for the effect, this paper established a wide-band equivalent circuit model of a hybrid high-voltage DCCB at the initial stage of DC fault. And revealed the mechanism of PDE: the stray inductance of series-connected solid-state switches, the junction capacitance of metal oxide varistors (MOVs), and the parasitic capacitance to the ground of DCCB form multiple resonant circuits. The external disturbance is converted into the interference of DCCB port through these stray parameters, and the interference would exceed the IGBT desaturation detection threshold. Furthermore, an equivalent experimental circuit that reproduces the electromagnetic interference of DCCB at the DC fault transient process was proposed, and the correctness of the mechanism analysis was verified by the scaled prototype of DCCB, the main resonance frequency error is less than 15%. Finally, the frequency domain and time domain characteristics of electromagnetic interference on the IGBT desaturation detection monitoring ports in 200kV DCCB at the initial stage of DC fault were analyzed. Based on these characteristics, a scheme of adding a delay time to the overcurrent protection criterion to avoid electromagnetic interference was proposed, which is adopted by an industrial project.

Analysis of Electromagnetic Interference for Anti-Medal UHF RFID Temperature Tag in High Power Electronic Equipment

Being inches from the rapid development of new energy technology, the capacity of high-power power electronic equipment is increasing rapidly, and the requirements for its safe and reliable operation are also rising. As a result, the demand for online temperature monitoring of such equipment is becoming increasingly urgent. RFID temperature measurement technology can be used for real-time monitoring of the temperature of powered operation equipment. However, the operation of high-power electronic equipment generates strong electromagnetic interference, which can seriously affect the normal operation of RFID temperature measurement systems. For applications involving the internal temperature measurement of high-power power electronic equipment, this paper employs an RFID anti-metal temperature tag antenna with a short-circuit cutoff structure. This structure was tested in an excitation switchgear cabinet. During the low-power operation of the cabinet, the temperature tag functioned normally. By combining an RFID antenna model with an electromagnetic interference simulation model of the main circuit of the excitation switchgear cabinet, this paper establishes an electromagnetic interference simulation model for an RFID temperature tag. It analyzes how the tag’s antenna performance parameters change when subjected to interference. Through simulation, the failure mechanism of the RFID temperature tag during the high-power operation of the excitation switchgear cabinet is clarified. The analysis found that there are both conductive electromagnetic interference and radiated electromagnetic interference in the excitation switchgear cabinet, with the conductive electromagnetic interference having a more significant effect. Conductive electromagnetic interference can seriously impact the performance of RFID temperature tags in the excitation switchgear cabinet, significantly degrading their performance. In contrast, the effect of radiated electromagnetic interference on the tags is relatively small. Therefore, this paper employs anti-metal RFID temperature tags and simulates and analyzes their electromagnetic interference characteristics.

Study on Characteristics of Electromagnetic Interference Caused by Metro Train Movement

With the rapid development of the urban power grid and metro system, their mutual influence has become more and more serious. The dc magnetic bias of the transformer caused by the metro becomes the main research direction. In this paper, the characteristics of dynamic electromagnetic coupling between metro trains and transmission lines are studied. First, the motion equation of the metro is written out according to the running law of the train, and three coupling relations are given according to the position of the train. The calculation method of dynamic induced voltage is deduced. Then the influence of parallel length and distance between the metro and transmission line on induced voltage is studied. The dynamic induction voltage increases first and then decreases with the increase of the parallel length of the metro and transmission line and decreases with the increase of the distance between them. It is proposed that the electromagnetic coupling of a single train has limited influence on the dc magnetic bias of transmission lines, but the influence of dynamic electromagnetic coupling cannot be ignored when multiple trains are running simultaneously.

Analysis of statistical method and variation characteristic parameters of very fast transient electromagnetic interference

The very fast transient overvoltage/overcurrent (VFTO/VFTC) signals generated during disconnectors switching operation may result in a significant threat to the reliability of power grids. While there are several commercial types of disconnectors, there is still a lack of understanding of the electromagnetic interference characteristics that is generated during the very fast transient process of the disconnectors. Based on the transient voltage and current data of disconnector capacitive small current test, this paper extracts the characteristics of the corresponding macropulse and monopulse waveforms. Also, the paper presents a comprehensive statistical analysis of the transient waveform characteristic data through probability density function fitting and Kolmogorov–Smirnov (K–S) test of the sample cumulative empirical distribution. The statistical results show that the probability density distribution of the switching operation macropulse waveform follows generalized extreme value and inverse gaussian distribution. The maximum peak values of VFTO and VFTC monopulse are found to be 50 kV and 370 A with a respective rise time at the range of nano- and micro-seconds.​ The frequency bands of VFTO and VFTC macro waveforms are basically distributed within 16 MHz. Results of this paper can pave the way into a more scientific basis for the design of disconnectors considering the strong electromagnetic disturbance and the formulation of system level electromagnetic compatibility standard tests, ensure the safe and stable operation of the power grid.

Space debris impact induced discharge and its radio emission characteristics

Small space debris impact induced discharge (SSDIID) and the subsequent electromagnetic interference is regarded as big threat to spacecraft safety. Using the on-ground simulation facility, the characteristic of SSDIID has been to some extent clarified, however, the relationship between impact induced discharge and the electromagnetic emission still remains elusive. In this work, we carry out the on-ground experimental simulation for the SSDIID and reveal its electromagnetic interference characteristics using the hypervelocity impact facility which comprises a plasma driving small space debris accelerator. We give the characteristics of the radio frequency radiation signal of SSDIID and analyze the interactions between the pulse electric field and the impact induced plasma. Specifically, we demonstrate that the impact induced discharge event can lead to very strong electromagnetic interference for the sensor circuit, which could be one fatal hazard for the spacecraft circuit system.

Electromagnetic compatibility analysis and interference shielding method for AcoustoElectric Logging Tool 2.0

Abstract Acoustoelectric logging is an important reservoir permeability evaluation method in the field of oil and gas exploration. Its complex composition, weak acoustoelectric signals, vulnerability to electromagnetic interference and other characteristics require high electromagnetic compatibility. In this study, after systematically analysing the interference characteristics of the detector, the electromagnetic protection measures are found to be largely inadequate. A complete shielding of the transmitting acoustic system was proposed. The shielding effectiveness was calculated and tested. In the test, the shielding suppression was ineffective, and the interference was enhanced by 60 dB instead. The explanation of conducted interference was given, and the conducted interference simulation prediction model was established. The simulation result explains the experimental result well. According to the suppression measurements provided by the model, the conducted interference was effectively suppressed, making the shielding effect of the transmitting acoustic system meet the design requirements.

Improvement of the SPICE Model of Diode Based on Measurement and Nonlinear Fitting Random Optimization Algorithm

This paper proposes a modeling method for improvement of the SPICE Model of a diode based on measurement and a nonlinear fitting random optimization algorithm. First, the mechanism of electromagnetic interference generated by diodes at high frequencies was analyzed: dynamic characteristic parameters such as reverse recovery of diodes and junction capacitance. Second, the method of obtaining the I-V characteristic curve and junction capacitance characteristics of the diode through testing was introduced in detail, and a nonlinear fitting random optimization algorithm was proposed to calculate the static and dynamic characteristic parameters of the diode, which can be applied to improvement of the SPICE model of the diode. A simulation and test circuit were built, and the simulation and test results were compared in the time and frequency domains. The model in this study can not only truly reflect the peak voltage owing to the electromagnetic interference characteristics, but also ensure that the harmonic components and component amplitudes are within three times the fundamental frequency, verifying the accuracy of the electromagnetic compatibility model.

Prediction of EMI Filter Attenuation in Power-Electronic Converters via Circuit Simulation

This article investigates the conducted-emission (CE) suppression characteristics of electromagnetic interference (EMI) filters used in power-electronic equipment by time-domain circuit simulation. An operational definition of insertion attenuation is introduced by comparing the CE in the absence and in the presence of the EMI filter. For the sake of exemplification, the analysis focuses on switched-mode dc–dc converters. It is shown that the EMI-filter attenuation behaves differently from the standard insertion loss (IL) and exhibits peculiar properties in these circuits. Namely, its response is known at discrete frequencies where the converter generates CE and may strongly depend on the harmonic index so to jump between quite different levels from a harmonic component to the next one, with a pseudoperiodic behavior, which can be related to the duty cycle. This effect is caused by circuit nonlinearity and is partially mitigated if the simulation accounts for two practically relevant aspects: random instability of the duty cycle and resolution bandwidth of the EMI receiver. The dependence of the common-mode (CM) and differential-mode attenuations on the loading conditions and duty cycle is analyzed, and it is shown that linear IL models provide reasonable predictions of CM attenuation only. Finally, experimental evidence of the unveiled phenomena is presented.

Wireless Communication in Modular Multilevel Converters and Electromagnetic Interference Characterization

The wireless control of modular multilevel converter (MMC) submodules was recently proposed. The success of the control depends on specialized control methods suitable for wireless communication and a properly designed wireless communication network in the MMC valve hall while aiming for low latency and high reliability. The wireless communication in the hall can be affected by the electromagnetic interference (EMI) of MMC submodules, voltage and current transients. In this article, firstly, a wireless communication network based on 5G New Radio is designed for an example full-scale MMC valve hall. After that, the radiated EMI characteristics of the MMC submodules with different voltage and current ratings and two dc circuit breakers are measured. The effects of EMI on wireless communication in the multi-GHz frequency band are tested. The interference from the components is confined below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {500 \text {M} \text {Hz} }$ </tex-math></inline-formula> , and the wireless communication with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {5825 \text {M} \text {Hz} }$ </tex-math></inline-formula> center frequency is not affected by the interference.

External Magnetic Field Minimization for the Integrated Magnetics in Series Resonant Converter

The resonant dc–dc converter is preferred for high-efficiency applications due to its less switching loss and better electromagnetic interference (EMI) characteristics. However, in a wide range of steady-state voltage gain applications, such as the on-board charger application, the wide output voltage range will lead to a bulky resonant inductor, which will decrease the power density. Magnetic integration of the inductor and transformer is an effective way to reduce the total magnetic volume. However, the traditional integrated magnetics of transformer and inductor will result in high magnetic field intensity in the external space nearby the integrated magnetic component. This external magnetic field will cause large eddy current losses in the neighboring metal heatsink and serious EMI issues. In order to deal with this problem, an integrated winding structure with a negligible external magnetic field is proposed in this article. By rebuilding the external winding segments with a better coupling coefficient, the external magnetic field intensity is canceled without efficiency and size sacrifices. Detailed analysis and design procedures of the proposed structure are presented. A 6.6-kW dc–dc prototype is built to verify the cancelation effect of the magnetic field intensity in the neighboring external space.

A Quantitative Analysis of Compromising Emanation From TMDS Interface and Possibility of Sensitive Information Leakage

This paper investigates the electromagnetic interference characteristics of the transition-minimized differential signaling (TMDS) scheme, a well-known technology for rapid serial data transmission, from a radio communication perspective. Such scrutiny regarding the leaking phenomenon inspires a pseudo model of the compromising signal model, which can simultaneously consider behavioral features of the software-defined radio with a simple RF front-end measuring the leakage. In this work, a conceptual explanation with mathematical formulations in implementing the pseudo model has been presented. Subsequently, by merging the model with various extra noises being in nature, the model can be utilized to facilitate and quantify the possibility of information extraction from the defected electromagnetic signatures. Furthermore, it is interesting to note that there are asynchronous problems due to inevitable timing errors in video display devices, even with a sophisticated acquisition system, turning out to be fatal for the frame-averaging scheme conducted before the signal demodulation. In view of these challenges, we have formulated a synchronizing scheme and verified validity by utilizing the pseudo model with the extra noise to take into account the asynchronous problem. Moreover, the structural similarity (SSIM), a function of the signal-to-noise ratio, can provide the number of frames for the frame-averaging process and eventually give the minimum acquisition time to earn meaningful information from the compromising emanation. Finally, after the appropriate post-processing, the extracted information from the actual measurements is compared with the reconstruction from the pseudo-model results revealing excellent agreements.

Coal Wall and Roof Segmentation in the Coal Mine Working Face Based on Dynamic Graph Convolution Neural Networks.

The intersection line information of the point cloud between the coal wall and the roof can not only accurately reflect the direction information of the scraper conveyor but also provide a preliminary basis for realizing the intelligent coal mine. However, the indirect method of using deep learning to segment the point cloud of coal mine working face cannot make full use of the rich information provided by the point cloud data. The direct method of using deep learning to segment the point cloud ignores the local feature relationship between points. Therefore, we propose to use dynamic graph convolution neural networks (DGCNNs) to segment the point cloud of the coal wall and roof so as to obtain the intersection line between them. First, in view of the characteristics of heavy dust and strong electromagnetic interference in the environment of the coal mine working face, we have installed an underground inspection robot so that we use light detection and ranging to obtain the point cloud of the coal mine working face. At the same time, we put forward a fast labeling method of the point cloud of the coal mine working face and an efficient training method of the depth neural network. Second, on the basis of edge convolution, being the greatest innovation of DGCNNs, we analyze the influence of the number of layers, K value, and output feature dimension of edge convolution on the effect of DGCNNs segmenting the point cloud of the coal mine working face and obtaining the intersection line of the coal wall and roof. Finally, we compare DGCNNs with PointNet and PointNet++. The results show that the DGCNN exhibits the best performance. What is more, the results provide a research foundation for the application of DGCNNs in the field of energy. Last but not least, the research results provide a direct and key basis for the adjustment of the scraper conveyor, which is of great significance for an intelligent coal mine working face and accurate construction of a geological information model.

Research on small lightweight electromagnetic interference measurement system based on patrol unmanned aerial vehicle

Unmanned aerial vehicle (UAV) has been widely used in power system inspection. Most of the existing UAVs are equipped with visible and infrared cameras for fast full spectrum photography and fault monitoring of transmission lines. When the transmission line has defects such as aging, broken strand and serious corrosion, the traditional image recognition, infrared and other observation methods can not identify these defects well. In order to realize the rapid detection and judgment of broken strand, this paper analyzes the characteristics of electromagnetic interference of transmission line, and constructs the electromagnetic interference measurement system based on patrol UAV. The research results of this paper can realize the real-time detection and alarm of broken strand, and provide technical support for line inspection.

Comprehensive performance analysis and optimal design of smart light pole for cooperative vehicle infrastructure system

Abstract On the basis of the finite element theory, in this study, a theoretical design and simulation practice to carry out steady-state static analysis, structural dynamics analysis, and electromagnetic interferencecharacteristics analysis on smart light poles, is combined. On this basis, a design of modular weight reduction and cost reduction was proposed, which realized the multi-objective parameter optimization of the smart light pole. The simulation results show that the mass of the optimized light pole can be reduced by 14.2%, and the material cost can be reduced by 14.7%. At the same time, the comprehensive performance of the optimized smart light pole can still meet the design requirements of the industry standards. The research results provide a reference for the lightweight design and the comprehensive analysis of the smart light pole in the future.

A Survey of Electromagnetic Influence on UAVs from an EHV Power Converter Stations and Possible Countermeasures

It is inevitable that high-intensity, wide-spectrum electromagnetic emissions are generated by the power electronic equipment of the Extra High Voltage (EHV) power converter station. The surveillance flight of Unmanned Aerial Vehicles (UAVs) is thus, situated in a complex electromagnetic environment. The ubiquitous electromagnetic interference demands higher electromagnetic protection requirements from the UAV construction and operation. This article is related to the UAVs patrol inspections of the power line in the vicinity of the EHV converter station. The article analyzes the electromagnetic interference characteristics of the converter station equipment in the surrounding space and the impact of the electromagnetic emission on the communication circuits of the UAV. The anti-electromagnetic interference countermeasures strive to eliminate or reduce the threats of electromagnetic emissions on the UAV’s hardware and its communication network.

Conducted EMI Investigation of a SiC-Based Multiplexing Converter for EV/PHEV

This paper investigates the conducted electromagnetic interference (EMI) characteristics of an on-board multiplexing converter that utilizes paralleled silicon carbide (SiC) devices to achieve high efficiency and high-power density for the application in electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs). The multiplexing converter can operate as a three-phase interleaved DC/DC converter with a peak output power of 60 kW or an integrated two-stage non-isolated on-board charger (OBC) with an output power of 6.6 kW. The novelty of this paper is that it reveals that in the DC/DC mode the series resonance between the input negative lead parasitic inductance and the high frequency transmission line effects of the input power inductor will increase the conducted EMI levels, which can be mitigated by optimizing the winding methods of the power inductor or by adding a small capacitor, and reveals that in the non-isolated OBC mode the shielded cable on the battery-side will increase the grid-side EMI in the low frequency ranges, which can be suppressed by integrated installation of EMI filters without affecting the system power density. Firstly, parasitic parameters of the components of the multiplexing converter, such as the power inductors, the SiC MOSFETs and the shielded cables, are extracted and validated with impedance measurements, and the corresponding equivalent circuit models are established. Then, the conducted EMI simulation models of the multiplexing converter in different working modes are established. The influence of different interference sources and different parasitic parameters on the system EMI characteristics are analyzed, and the effective EMI suppression measures are given without affecting the system power density. Finally, the conducted EMI characteristics of the multiplexing converter and the effectiveness of the proposed EMI suppression measures are tested and verified through experiments.

Optimization Technology of Optical Fiber Communication Network Based on Service Classification

Optical fiber has huge bandwidth, as a physical medium, it has good anti electromagnetic interference characteristics and excellent security performance, which is very suitable for the establishment of backbone transmission network. Wavelength division multiplexing(WDM) network based on optical fiber has been widely used. Using optical fiber for information transmission can give full play to the nearly unlimited transmission capacity of optical fiber. With the advent of the information age, data service has become the mainstream business, replacing the original telephone voice service. The great development of data transmission service further promotes the continuous development of WDM network technology. Among all kinds of services in optical network, IP service accounts for the largest proportion. In optical networks, switching is an important technology. Network performance is directly related to switching technology. With the development of optical communication technology, a variety of optical switching devices are introduced into WDM optical network, such as optical packet switching, optical burst switching and so on. This makes WDM layer have the ability of dynamic path establishment and removal similar to IP layer. In order to improve the performance of the optical network and reduce the blocking rate of the network, in WDM optical network, the services are designed in different levels. For some very important services, the highest priority is given, and the optical path channel with better survivability and higher fault tolerance is selected. For general services, it can be designed as a lower level service, and choose the appropriate optical path channel for transmission. The experimental results show that this hierarchical service design method can make more effective use of network resources, reduce the network blocking rate, and improve the overall performance of the network.

Optimal Design of Multi-Output LLC Resonant Converter with Independently Regulated Synchronous Single-Switched Power-Regulator

This paper presents a tightly regulated multi-output isolated converter that employs only an independently regulated synchronous Single-Switched Post-Regulator (SSPR). The proposed converter is a highly accurate single-ended secondary side post-regulator based on a Series Resonant Converter (SRC); furthermore, it has a voltage-doubler characteristic. The proposed post-regulator requires only one auxiliary switch, in contrast with a bulky and expensive non-isolated DC–DC converter. Moreover, the added voltage-doubler can tightly regulate the slave output current. In addition, the voltage-doubler can improve electromagnetic interference characteristics and reduce switching losses arising from the Zero Current Switching (ZCS) operation of all power switches. The validity of the proposed converter is verified using experimental results obtained via a prototype converter applicable to an LED 3D TV power supply.