Frequency Electromagnetic Interference Research Articles

NLOS visible light positioning and communication based on LoRa modulation.

With the rapid development of the Internet of Things, location-based services are becoming increasingly important, especially in indoor environments. Visible light positioning (VLP) has garnered widespread attention due to its high accuracy, low cost, and immunity to the radio frequency electromagnetic interference. However, traditional VLP relies on line-of-sight paths, making it impractical in complex and dynamic indoor environments. In this paper, we propose a non-line-of-sight (NLOS) visible light positioning and communication system based on LoRa modulation to address the issue of link obstruction. LoRa is employed to recover position information transmitted from light emitting diodes (LEDs) over NLOS links, enabling reliable communication under weak lighting conditions. We establish a geometric relationship between the LED and the virtual image of the photodetector (PD). Leveraging the NLOS channel model, we derive the relationship between the received signal strength and the distance from LEDs to the virtual image of the PD. Through this relationship, the trilateration method is applied to calculate the position of the receiver. Based on experimental results, the proposed system achieves 90th percentile localization accuracy of less than 25 and 35 cm for the PD heights of 60 and 80 cm, respectively.

An Electromagnetic Interference Immune PAM-4 Transceiver System

This article presents the design of a pulse amplitude modulation (PAM-4) transceiver that supports high-speed wireline communication in the presence of electromagnetic interference (EMI). The proposed PAM-4 transceiver uses an input level shifter (ILS) and a modified electrostatic discharge (ESD)-protection circuit to reduce the effects of EMI at the transmitter. In order to overcome the effects of EMI at the receiver, the front end is designed with an enhanced input common-mode range. The transverse electromagnetic (TEM) cell method, as provided in the IEC 62132-2 standard, is followed to experimentally verify the radiated EMI-immunity of the proposed PAM-4 transceiver system over its traditional counterpart. For proof of concept, the proposed EMI-immune PAM-4 transceiver and the traditional PAM-4 transceiver circuits are implemented using the 130-nm BiCMOS process. The proposed transceiver operates at a data rate of 6.5 Gbps while maintaining an eye-opening of 70 mV for each bit in the presence of EMI, meeting the requirement of the IEEE 802.3 bs standard. The proposed PAM-4 transceiver withstands a wide range of EMI frequencies that span from 150 kHz to 2 GHz with an EMI power of 0–20 dBm.

Multi-Amplification-Channel Active EMI Filter Based on Period Spread-Spectrum PWM for Common-Mode EMI Suppression

Due to the existing coupling loop between the motor drive system and the ground, when switching devices in the drive system operate at a high speed, common-mode (CM)-conducted electromagnetic interference (EMI) is generated in the loop. The electromagnetic environment quality of the motor and peripheral equipment is reduced. As a small and lightweight EMI suppression device, the active EMI filter (AEF) can be used in the motor drive system to suppress the CM-conducted EMI. As the unity gain bandwidth of the operational amplifier (OPAMP) in the AEF is fixed, the CM-conducted EMI suppression effect of the AEF is poor. To solve this problem, the multiple-amplification-channel method is used to spread the frequency range of the CM voltage that the AEF can sense; therefore, the frequency of the compensation current output using the AEF is more complete, and a better CM-conducted EMI attenuation effect is obtained. At the same time, a combination of the period frequency carrier modulation (PCFM) and the multi-amplification-channel AEF is adopted so that the CM-conducted EMI in the whole EMI frequency range of the motor drive system is effectively suppressed.

Design and Analysis of Broadband Power Delivery Network Noise Absorber for Parallel-Plate Mode Suppression

In this article, a broadband power delivery network (PDN) noise absorber with its 90%-absorption band from 4 to 7.5 GHz is proposed to suppress parallel-plate modes. Due to the ever-increasing switching speed of integrated circuits (ICs) nowadays, a few millimeters separating a chip and the conventional reflective filters may induce significant power noises and cause serious radio frequency interference (RFI) and electromagnetic interference (EMI) problems. In this scenario, PDN noise absorbers can prevent power noises from both reflecting and transmitting, thus avoiding cavity resonances, providing a clean and stable power supply, and achieving almost zero radiation. Four cases were compared to verify all these advantages of the PDN noise absorbers. For conducted noises around 6 GHz, the self-impedance peak is suppressed by 86.9% at the noise source end and the insertion loss is almost the same level at the transmitted end when compared with the case of two rings of the reflective filters. Furthermore, almost 100% of the radiative noises are cleared away by the proposed PDN noise absorbers.

Performance limits of high voltage press-pack SiC IGBT and SiC MOSFET devices

Considering the switching frequency limit and electromagnetic interference, the selection of high voltage SiC IGBT and SiC MOSFET is confusing due to punch-through effect and bipolar characteristics of SiC IGBT. The thermal resistance, static characteristics and dynamic characteristics of SiC IGBT and SiC MOSFET module with Press-Pack packaging are measured to evaluate the switching frequency limit and electromagnetic interfere of them. The tradeoffs of SiC IGBT between switching frequency limit and electromagnetic interfere are less attractive due to the intrinsic characteristics, such as high power loss and punch-through effect. The possible solutions for SiC IGBT are proposed based on the improvement of driving resistor and driving voltage.

Design of a Modified Single-Stage and Multistage EMI Filter to Attenuate Common-Mode and Differential-Mode Noises in SiC Inverter

The SiC inverter switching at high frequencies introduces increased common-mode (CM) and differential-mode (DM) electromagnetic interference (EMI) issues, such as shaft voltage, bearing currents, insulation degradation, and poor current quality in the motor. These EMI issues are commonly addressed with EMI filters employing CM and DM inductors. The increased volume and poor performance of a CM inductor designed for SiC inverter switching at high frequency require a modified EMI filter design procedure for enhanced performance and volume minimization. In this work, three EMI filters are presented with modified design procedures. A single-stage EMI filter is designed by incorporating a DM filter offering an equal attenuation to DM and CM noise at switching frequency. Here, the additional CM attenuation demand is fulfilled by a marginal value of the CM inductor, while, in multistage EMI filters, the required CM attenuation is split between the two stages. The multistage EMI filter 1 is designed using an additional CM inductor and existing load capacitance as the second stage, whereas the multistage EMI filter 2 is designed with a lesser value of CM inductance to provide CM attenuation over the entire conducted EMI frequency range. The modified EMI filters are tested on an SiC inverter operating at 200 kHz.

Study of the substrate surface treatment of flexible polypyrrole-silver composite films on EMI shielding effectiveness: theoretical and experimental investigation

Abstract Conductive flexible polypyrrole-silver (PPy-Ag) composite films were prepared on Biaxial Oriented Polyethylene Terephthalate (BOPET) substrate with surfaces treated by (3-aminopropyl) trimethoxysilane (APTMS). The surface treatment was carried out to improve the adhesion, morphology, and electrical properties of the deposited film to enhance the Electromagnetic Interference Shielding Effectiveness (EMI-SE). APTMS grafting on the BOPET substrate was confirmed by X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) analyses. All structural, morphological, and electrical features of PPy-Ag raised from different AgNO3 molar ratio were investigated. The shielding effectiveness properties, experimentally determined for the synthesized PPy-Ag films were compared to those simulated analytically and numerically based on the transmission line matrix method (TLM). Both analytical and numerical models showed a good agreement with experimental measurements. The obtained results confirmed that the PPy-Ag films of 0.5 M/1 M molar ratio exhibits high EMI shielding performance of about 21 dB along with an electrical conductivity of 47 S/cm. Therefore, the treated surface flexible PPy-Ag films can be considered as potential candidate for high frequency electromagnetic interference shielding applications.

Harmonics Suppression of AC Source Current of a Single Phase Source Fed Induction Heating System

Any high frequency Induction heating system while undergoing through very high frequency switching operations, produces Electromagnetic Interference (EMI) noises or very high frequency harmonics within the system. These high frequency EMI noises conductively propagate towards the input AC source and distort the sinusoidal input AC current and make it non-sinusoidal. The desired performance from the induction heating cannot be anticipated. As such, it is inevitable to eliminate such EMI noises from the input AC source current to get the desired performance. Here, a specially designed ring type LC low pass passive filter is proposed which can accomplish to suppress these high frequency EMI noises up to satisfactory level and can restore the sinusoidal shape in the input AC source current waveform and thus improves the power quality of the AC supply for the induction heating system. The impact of the induction heating system without and with incorporating the proposed filter will be compared in this study.

EMI Performance of Active Neutral Point Clamped Phase Leg for Dual Active Bridge DC–DC Converter

This article evaluates the electromagnetic interference (EMI) caused by active neutral point clamped (ANPC) phase leg undergoing zero voltage switching (ZVS). ZVS, together with a high fundamental frequency operation is encountered in dual active bridge (DAB) converters. This allows ANPC phase leg to be operated in a different manner than its inverter counterpart. A comprehensive evaluation of four switching schemes for NPC/ANPC-DAB with regard to their EMI performance, voltage overshoot, and losses have been done. Switching state redundancies have been used to reduce the EMI of the ANPC phase leg. To further help in reduction of high frequency EMI and voltage overshoot, a low inductance busbar design has been presented for through-hole discrete devices. Finite element simulation and measurement results show a busbar inductance of 7.7 nH for long commutation loops. Finally, EMI performance (conducted and radiated) together with the busbar design has been experimentally validated for two of the most useful switching schemes. The switching schemes and the busbar design can boost adoption of NPC/ANPC-DAB by ensuring EMI compliance and improved efficiency without affecting the normal DAB operation or using additional hardware.

Protecting COVID-19 Vaccine Transportation and Storage from Analog Cybersecurity Threats

Protecting COVID-19 Vaccine Transportation and Storage from Analog Cybersecurity Threats

Effectiveness of Frequency Diversity to Create EM-Diversity in Triple-Modular Redundant Data Transmission Systems

This article investigates the effectiveness of frequency diversity, the usage of three different frequencies inside a triple modular redundant data transmission system, to cope with harsh electro-magnetic disturbances. Such a triple modular redundant system uses three different data channels to transmit data after which majority voting is applied to conclude one final output. Using a Monte-Carlo based simulation framework calculates the influence of harsh electromagnetic disturbances on the communication channel. The bit error rate and the amount of undetectable dangerous failures are calculated, and serve as a quality measure for our study. In addition, this article describes a semianalytical model that implements the critical factors that are necessary to get comparable results to the Monte-Carlo simulation framework, with less computational effort. To find the bit frequencies that optimize the bit error rate (BER), and minimize the amount of dangerous failures, a sweep is performed over two out of three data frequencies while fixing the third data frequency, and the electromagnetic interference (EMI) frequency. Notable relationships are recognized in the visual results and further studied. This results in six equations visualizing the relationships between the data and EMI frequencies. Finally, three equations predict the prospective BER, and undetectable failures, which is confirmed using the Monte-Carlo simulation framework.

SAR Interference Suppression Algorithm Based on Low-Rank and Sparse Matrix Decomposition in Time–Frequency Domain

Radio frequency electromagnetic interference is a relatively common phenomenon, especially for synthetic aperture radar (SAR) systems working in P- or L-band. Compared with the suppression of narrowband interference, that of wideband interference, particularly of those whose signal parameters have frequently changing property, is still a sophisticated problem. In this letter, a suppression algorithm for interference with wideband and complicated parameters is proposed, based on low-rank and sparse matrix decomposition (LRSMD) in time–frequency domain (TFD) of the signal. The proposed algorithm begins with transforming the SAR signal into TFD. After that, LRSMD based on bilateral random projection (BRP) is applied to decompose the time–frequency spectrum matrix into three parts, a low-rank matrix standing for interference, a sparse matrix standing for SAR signal, and a noise matrix. Finally, inversely transform the sparse matrix into the time domain to obtain SAR signal without interference. The proposed algorithm is applied to a single look complex (SLC) SAR data of Sentinel-1 to validate its effect and efficiency.

Polymeric materials for electromagnetic shielding - A review

With advent of modern technology, there is a rapid rise in growth of electronic devices which in-turn creates radio frequency interference (RFI) and electromagnetic interference (EMI).This demands an extensive research in EMI shielding materials as the modern electronic devices malfunctions due to EMI generated. In general, high electrical conductivity metals and their alloys have served as ideal shielding materials due to their high shielding effectiveness (SE). Their disadvantages like heavy weight, rigidity and corrodibility has increased the research on development of alternatives to serve purpose of EMI shielding. Hence, it is necessary to develop lightweight, thin, and easy-to-design EMI shielding materials for electronic device. In addition, if the selected material is biodegradable and environment friendly, it will add advantage to it. Polymeric materials and their composites have been used as EMI shielding materials due to their characteristics like light weight, good corrosive resistance, superior electrical, dielectric, thermal, mechanical and magnetic properties. Also, it can be degraded without creating any environment pollution. In this review article, shielding effectiveness of various polymeric materials and their composites have been deeply reviewed. In addition, this article covers the various nano-fillers and other materials that can be added along with polymers for EMI shielding.

1D‐CNN based real‐time fault detection system for power asset diagnostics

Electromagnetic interference (EMI) diagnostics aid in identifying insulation and mechanical faults arising in high voltage (HV) electrical power assets. EMI frequency scans are analysed to detect the frequencies associated with these faults. Time-resolved signals at these key frequencies provide important information for fault type identification and trending. An end-to-end fault classification approach based on real-world EMI time-resolved signals was developed which consists of two classification stages each based on 1D-convolutional neural networks (1D-CNNs) trained using transfer learning techniques. The first stage filters the in-distribution signals relevant to faults from out-of-distribution signals that may be collected during the EMI measurement. The fault signals are then passed to the second stage for fault type classification. The proposed analysis exploits the raw measured time-resolved signals directly into the 1D-CNN which eliminates the need for engineered feature extraction and reduces computation time. These results are compared to previously proposed CNN-based classification of EMI data. The results demonstrate high classification performance for a computationally efficient inference model. Furthermore, the inference model is implemented in an industrial instrument for HV condition monitoring and its performance is successfully demonstrated in tested in both a HV laboratory and an operational power generating site.

Electromagnetic Disturbed Mechanism of Electronic Current Transformer Acquisition Card under High Frequency Electromagnetic Interference

The electronic current transformer (ECT) acquisition card is widely used in smart grids with many advantages. However, with the continuous improvement of the power grid and localized intelligent electronic devices, the electromagnetic environment under the operating conditions of gas insulated switchgear (GIS) substations is becoming more complicated. The reliability and safety of the ECT acquisition card will be endangered due to the complicated electromagnetic environment. In order to solve these problems, this paper investigates the electromagnetic disturbed mechanism of the ECT acquisition card. The effects of different grounding methods on the electromagnetic interference of the ECT acquisition card were studied. A platform based on IEC 61000-4-4 was built, and the electromagnetic interference (EMI) of the ECT acquisition card with different grounding methods was measured. The results show that the lower grounding impedance of the ECT acquisition system increased the internal EMI. Further, the high frequency electrical fast transient/burst coupling mechanism was analyzed. The parasitic parameters of the acquisition card were extracted based on the critical circuit by using the finite element method. Then, the high-frequency EMI coupling model of the ECT acquisition card was established.

Closed-Loop Gate Drive for Single-Ended Forward Converter to Reduce Conducted EMI

Forward DC/DC converters are widely used in low and medium power circuits that are widely used in the aerospace and navigation fields. Power converters are usually sources of electromagnetic interference (EMI), which is due to their higher voltage and current transients. The traditional method is to add expensive filters on the primary side or the secondary side, but its disadvantages are high cost and poor adjustability. Based on the principle that the greater the number of derivations of voltage transients, the lower the high frequency electromagnetic interference contained in this voltage, a signal containing small high-frequency noise that is suitable for the hardware circuit as a reference signal is selected, and a closed-loop gate drive method is used in this paper, which attenuate the conducted EMI noise in the input bus of the forward DC/DC converter. The reference signal shapes the output signal to achieve the purpose of suppressing electromagnetic interference through the closed loop circuit. The advantages of this method are making the output highly adjustable, reducing hardware size and weight and lower cost compared with filter method. Compared with the method of controlling current to reduce electromagnetic interference, the proposed method is easier to implement. Firstly, the relationship between the derivative order of voltage transient and electromagnetic interference is introduced. Secondly, the experimental principle of single-ended forward circuit controlled by closed loop is introduced. Simulation and experimental results show that the proposed method can achieve voltage shaping and suppression of voltage overshoot effectively. Compared with the traditional hard-switching control method, the proposed method can make the high-frequency components of the drain-source voltage of the primary-side MOS transistor and the secondary-side output voltage have a greater attenuation.

Multi-resolution wavelet analysis for noise reduction in impulse puncture voltage measurements

This work describes an approach for digital processing of voltage impulse signals in puncture tests of insulators on high voltage laboratories, using wavelet transform based multi-resolution analysis. Quantifying the amplitude of such impulses is not a trivial task because they have typical magnitudes of hundreds of kilovolts and rise times of 100 ns to 200 ns. The processing is mainly necessary due to high frequency electromagnetic interferences caused by the impulse generation system, which may strongly affect the measurement accuracy and, consequently, the test result. This manuscript presents qualitative and quantitative results for different types of wavelets studied, as well as the best performance obtained by the filter. Software for signal processing and analysis was also developed for this application. Results are also presented using the wavelet filter for a pioneering inter-laboratory comparison between high voltage measuring systems used in impulse puncture tests of insulators.

Study of the Effect of Low-Frequency Interference on Resistance-to-Voltage Converter in Cable Insulation Testing

The study focuses on the effect of low-frequency noise on resistance converter of teraommeters to test cable insulation. A mathematical pendulum was used to simulate low frequency electromagnetic interference. It was found that the greatest effect is exerted by dynamic effects of electrostatic charges that accumulate on the printed circuit board, electronic components, structural elements of the resistance-to-voltage converter, and on the test cable sheath. The effect of constant and alternating magnetic fields on measurement of resistance of insulating materials is insignificant.

Structural and high GHz frequency EMI (electromagnetic interference) properties of carbonyl iron and boron nitride hybrid composites

Hybrid (mix of magnetic Carbonyl Iron and dielectric ceramic Boron Nitride) powders, composites and methods for making these powders that are potentially useful for high frequency EMI (electromagnetic interference) applications are described here. Comparative study of polymer composites, made using these hybrid powders by a speed mixing process and a high energy ball milling method (HEBM), has been conducted and their properties (microstructural and electromagnetic) have been characterized at high GHz frequency bands. Magnetic permeability values of the two different samples are widely different and magnetic loss tangent values for hybrid flakes made using a HEBM process is considerably higher than speed mixed samples, especially at lower GHz frequencies. However dielectric loss tangent values are similar for both samples. EMI (Electromagnetic Interference) absorbing performance of the composites made using the two different hybrid fillers is also compared at 18–40 GHz frequency band using a radar absorption model. It was observed that the speed mixed hybrid filler composite samples show much better EMI absorber performance with a minimum reflection loss value of −12.5 dB at a frequency of 34.5 GHz which is useful for many new emerging industrial applications.

Experimental Demonstration of Single-Channel EEG Signal Using 32 × 32 Pixel OLED Screen and Camera

Currently, the radiofrequency (RF)-based wireless technology deployed in electroencephalography (EEG) to diagnose brain diseases suffers from frequency spectrum and electromagnetic interference, and might also have adverse effects on the health of patients and equipment used in hospitals, especially in RF-restricted zones like intensive care units (ICUs). Optical wireless communication (OWC), specifically visible light communication (VLC), is featured in 5G network to complement the radiofrequency (RF) technologies due to the fact that huge unlicensed bandwidth and available infrastructure, both indoor and outdoor, reduces the implementation cost. The conventional VLC systems deploy photodiodes as receivers, requiring hardware and infrastructure modifications in addition to smaller field of view (FOV), but the use of cameras reduce the infrastructure cost due to inbuilt filters and a wider FOV coverage gives the ability to scale a larger area. The wider FOV and the movement of camera rotation, without any additional adjustments to maintain the line-of-sight (LOS), allows the patient to be anywhere within the room and FOV. This paper demonstrates a novel healthcare system for EEG using visible light optical camera communication (VL-OCC), where a 32 × 32 pixel OLED screen acts as transmitter and the receiver section consists of several different cameras such as digital single-lens reflex camera (DLSR), android smartphone, and Thorlabs camera. The experiments were performed in LOS deploying on-off keying (OOK) modulation at several distant measurements to determine the system reliability and stability through bit error rate (BER) performance. The proposed system results depict that the DSLR camera outperforms the smartphone and Thorlabs cameras, as it is capable of transmitting an error free bit rate of 2.8 kbps at 30 fps up to 5.5 m.