Electromagnetic Interference Suppression Research Articles

Hybrid spread spectrum modulation-based electromagnetic interference suppression of vehicle DC/DC converters

Hybrid spread spectrum modulation-based electromagnetic interference suppression of vehicle DC/DC converters

Dielectric‐Based Metamaterials for Near‐Perfect Light Absorption

AbstractThe emergence of metamaterials and their continued prosperity have built a powerful working platform for accurately manipulating the behavior of electromagnetic waves, providing sufficient possibility for the realization of metamaterial absorbers with outstanding performance. However, metamaterial absorbers composed of metallic materials typically possess many unfavorable factors, such as non‐adjustable absorption, easy oxidation, low‐melting, and expensive preparation costs. The selection of dielectric materials provides excellent alternatives due to their remarkable properties, thus dielectric‐based metamaterial absorbers (DBMAs) have attracted much attention. To promote breakthroughs in DBMAs and guide their future development, this work systematically and deeply reviews the recent research progress of DBMAs from four different but progressive aspects, including physical principles; classifications, material selections and tunable properties; preparation technologies; and functional applications. Five different types of theories and related physical mechanisms, such as Mie resonance, guided‐mode resonance, and Anapole resonance, are briefly outlined to explain DBMAs having near‐perfect absorption performance. Mainstream material selections, structure designs, and different types of tunable DBMAs are highlighted. Several widely utilized preparation methods for customizing DBMAs are given. Various practical applications of DBMAs in sensing, stealth technology, solar energy absorption, and electromagnetic interference suppression are reviewed. Finally, some key challenges and feasible solutions for DBMAs’ future development are provided.

Magnetic integration of a symmetrical LCL filter in the grid‐tied inverter with reduced EMI noise

AbstractHarmonics and electromagnetic interference (EMI) pose serious threats to the safety and efficiency of grid‐tied inverters. Although the inductor‐capacitor‐inductor (LCL) filter offers commendable harmonic suppression, it does not sufficiently mitigate leakage current and EMI caused by high‐frequency pulse‐width modulation (PWM). This paper examines the use of a symmetrical LCL filter to reduce the AC side leakage current in grid‐tied inverters. The symmetrical structure bolsters the conducted EMI suppression capability of the LCL filter. A magnetic integration scheme for symmetric LCL filters is introduced, and through thoughtful structural design, it achieves filter inductance integration on the EIE magnetic core. An experimental platform, equipped with a high‐frequency SiC‐MOSFET voltage source inverter with a 600 W output, is utilized. The LCL filter, symmetric LCL filter, and magnetic integrated symmetric LCL filter are contrasted, proving the effectiveness and feasibility of the proposed scheme. Furthermore, the experimental results demonstrate that the proposed magnetic integration scheme significantly reduces the filter's volume and weight, thereby enhancing the power density of the grid‐tied inverter system.

Broadband microwave coding absorber using genetic algorithm

Microwave absorbers play a crucial role in various applications, including radar cross-section reduction, electromagnetic interference suppression, and stealth technology. However, designing a metamaterial absorber with broadband, polarization-independent, and wide-angle absorption characteristics remains a significant challenge. In this work, we study a design of a broadband, polarization-independent microwave coding metamaterial absorber using a genetic algorithm. The genetic algorithm is employed to optimize the topology of unit cells to achieve an average absorption of approximately 95% across an extensive frequency range of 17−26 GHz. The designed absorber maintains its high absorption performance for incident angles up to 50° and is unaffected by the polarization of the incident wave. Preliminary experimental results appear to support the numerical and theoretical analysis. Moreover, the proposed topological optimization method can be extended to design absorbers quickly and efficiently, paving the way for the development of advanced microwave devices and applications.

Recent Advances in Electromagnetic Interference Suppression

With the increasing popularity and complexity of electronic equipment, the problem of electromagnetic interference (EMI) has become increasingly prominent. Such interference can seriously affect the performance, reliability, and service life of the device and, in severe cases, may cause system failure or communication interruption. Existing EMI suppression techniques are widely used to address this issue, and this paper provides a comprehensive overview. Firstly, it introduces the impact and harm of EMI on us and then presents two forms of EMI, namely conducted EMI and radiated EMI, better to understand the sources and characteristics of these disturbances. Three different EMI filters, the advantages of soft switching compared to hard switching, the working principle of random modulation, and emerging trends in electromagnetic shielding are then analyzed and discussed. Finally, we comprehensively summarize the advantages and disadvantages of the above four methods and point out the possible limitations of each technique in practical applications. We also propose potential future research directions, which will help to overcome the shortcomings of existing technologies and promote the development of the field of EMI suppression.

A Review of EMI Research of High Power Density Motor Drive Systems for Electric Actuator

With the global attention given to energy issues, the electrification of aviation and the development of more electric aircraft (MEA) have become important trends in the modern aviation industry. The electric actuator plays multiple roles in aircraft such as flight control, making it a crucial technology for MEA. Given the limited space available inside an aircraft, the power density of electric actuators has become a critical design factor. However, the pursuit of high power density results in the need for larger rated power and higher switching frequency, which can lead to severe electromagnetic interference (EMI) issues. This, in turn, poses significant challenges to the overall reliability of the electric actuator. This paper provides a comprehensive review of EMI in high power density motor drive systems for electric actuator systems. Firstly, the state of the art of electric actuator systems are surveyed, pointing out the contradictory relationship between high power density and EMI. Subsequently, various EMI modeling approaches of motor control systems are reviewed. Additionally, the main EMI suppression methods are summarized. Active EMI mitigation methods are emphasized in this paper due to their advantages of higher power density compared with passive EMI filters. Finally, the paper concludes by summarizing the EMI research in motor drive systems and offering the prospects of electric actuators.

Ultra-wideband electromagnetic interference suppression lightweight metamaterial absorber based on S/C/X frequency band

Ultra-wideband electromagnetic interference suppression lightweight metamaterial absorber based on S/C/X frequency band

Conducted electromagnetic interference mitigation in super-lift Luo-converter for electric vehicle applications

In this article, a digital chaotic pulse width modulation (DCPWM)-dependent electromagnetic interference (EMI) noise attenuating procedure has been implemented. With the aid of a field programmable gate array (FPGA), a randomized carrier frequency modulation with a fixed duty cycle has been generated through chaotic carrier frequency, and this process is called DCPWM. Conducted EMI suppression is achieved in a 200 kHz, 40 W elementary positive output super lift Luo (EPOSLL) converter using the DCPWM technique. The results are compared and validated with periodic PWM over DCPWM in simulation and hardware with electromagnetic compatibility (EMC) standards. Besides, 9 dBV (2.81 V) of conducted EMI noise has been minimized in the DCPWM approach against periodic pulse width modulation method for the EPOSLL converter in electric vehicles applications.

Butler matrix-based beamforming with polarization reconfigurability for reducing electromagnetic interference

In this paper, Circular-Polarization (CP) reconfigurability, switched beamforming, and Side Lobe Level (SLL) reduction necessary for electromagnetic interference suppression are achieved thanks to a novel modified single-layer 4×8 Butler Matrix (BM). The proposed feeding network is capable of exciting a linear array composed of four square patch antennas. Each antenna element is fed from its both adjacent edges with a ±90°phase difference, thus resulting in Left-Handed or Right-Handed Circular Polarizations (LHCP or RHCP). The suggested feeding network also reduces the SLL by engendering tapered amplitude distributions in its output ports. This feature has been introduced for the first time in a system providing simultaneous beam switching and polarization reconfigurability. It should be mentioned that beamforming is performed as the BM can generate progressive phase differences regarding the input port selected for the excitation. All the above-mentioned characteristics are well received by a straightforward and flexible modification in 4×8 BM. A sample of the structure operating at 2.4 GHz is designed, fabricated, and measured. Furthermore, the theta bandwidth in both RHCP and LHCP cases is evaluated, showing the full coverage of azimuth plane from –60 to 60 degree with an Axial Ratio (AR) below 3 dB.

A direct laser-synthesized magnetic metamaterial for low-frequency wideband passive microwave absorption

Microwave absorption in radar stealth technology is faced with challenges in terms of its effectiveness in low-frequency regions. Herein, we report a new laser-based method for producing an ultrawideband metamaterial-based microwave absorber with a highly uniform sheet resistance and negative magnetic permeability at resonant frequencies, which results in a wide bandwidth in the L- to S-band. Control of the electrical sheet resistance uniformity has been achieved with less than 5% deviation at 400 Ω sq−1 and 6% deviation at 120 Ω sq−1, resulting in a microwave absorption coefficient between 97.2% and 97.7% within a 1.56–18.3 GHz bandwidth for incident angles of 0°–40°, and there is no need for providing energy or an electrical power source during the operation. Porous N- and S-doped turbostratic graphene 2D patterns with embedded magnetic nanoparticles were produced simultaneously on a polyethylene terephthalate substrate via laser direct writing. The proposed low-frequency, wideband, wide-incident-angle, and high-electromagnetic-absorption microwave absorber can potentially be used in aviation, electromagnetic interference (EMI) suppression, and 5G applications.

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.

Transformation from Electromagnetic Inflection to Absorption of Silicone Rubber and Accordion-Shaped Ti3C2MXene Composites by Highly Electric Conductive Multi-Walled Carbon Nanotubes.

Electromagnetic (EM) pollution becomes more penetrating in daily life and work due to more convenience provided by multi-electrical devices, as does secondary pollution caused by electromagnetic reflection. EM wave absorption material with less reflection is a good solution to absorb unavoidable EM radiation or reduce it from the source. Filled with two-dimensional Ti3SiC2MXenes, silicone rubber (SR)composite demonstrated a good electromagnetic shielding effectiveness of 20 dB in the X band by melt-mixing processes for good conductivity of more than 10-3 S/cm and displayed dielectric properties and a low magnetic permeability; however, the reflection loss was only -4 dB. By the combination of one-dimensional highly electric conductive multi-walled carbon nanotubes (HEMWCNTs) and MXenes, the composites achieved the transformation from electromagnetic inflection to an excellent absorbing performance to reach a minimum reflection loss of -30.19 dB due to electric conductivity of above 10-4 S/cm, a higher dielectric constant, and more loss in both dielectric and magnetic properties. Ni-added multi-walled carbon nanotubes were not able to achieve the transformation. The as-prepared SR/HEMWCNT/MXene composites have potential application prospects in protective layers, which can be used for electromagnetic wave absorption, electromagnetic interference suppression of devices, and stealth of the equipment.

A Method for CM EMI Suppression on PFC Converter Using Lossless Snubber with Chaotic Spread Spectrum

This paper proposes an improved common mode (CM) electromagnetic interference (EMI) suppression method in switching power supplies. The lossless snubber circuit can reduce du/dt and EMI in the high-frequency band. Nevertheless, it has a weak EMI suppression effect on the low-frequency band. A method combining the chaotic spread spectrum and the lossless snubber (CSS–LS) is proposed to improve the EMI suppression effect of the lossless snubber. It is an effective means to suppress CM EMI further. The paper used a Boost PFC converter as the object of analysis to study the CM EMI suppression effect of CSS–LS. Firstly, a CM EMI-equivalent model of the lossless snubber PFC converter was established. Then, the power spectral density function under chaotic spread-spectrum modulation was derived. The simulation analysis was performed. Finally, an experimental prototype was built, and relevant EMI tests were carried out. The experimental results show that CSS–LS can reduce CM EMI by 4~20 dBµV with little impact on converter stability. Fewer extra costs are needed for this optimization method, which is suitable for high-power-density power electronic devices.

A Novel Patterned Ground Structure With Shunt and Series Lumped Elements for Synthesizing Absorption Common-Mode Filters

To synthesize an absorption common-mode filter (A-CMF) in a two-layer printed circuit board, patterned ground structures (PGSs) have been studied in the past few years. A conventional PGS consists of slotlines and shunt lumped elements across slots. On the contrary, the proposed new PGS uses both shunt and series lumped elements (SSLEs) in a ground plane with a closed-loop asymmetrical coplanar strip. To validate the proposed SSLE PGS, two circuits of bidirectional A-CMFs are developed to absorb common-mode (CM) noise in the 2.4 GHz industrial scientific medical (ISM) band. The one with higher CM noise absorption bandwidth is finally implemented and demonstrated in this article. Besides, nonideal CM return current paths are considered to modify the ideal circuit and reduce the discrepancies between the full-wave and circuit simulations. The measurement results show that the proposed bidirectional A-CMF attains CM noise absorption from 2.29–2.57 GHz for electromagnetic interference suppression in the 2.4 GHz ISM band. Most of all, the proposed work reveals a notable differential-mode −3 dB bandwidth up to 16.3 GHz with an ultracompact size of 0.0143 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _g^2$</tex-math></inline-formula> .

Spoof surface plasmon polaritons based on-chip sensor for dielectric detection.

A compact millimeter-wave on-chip sensor for dielectric detection is presented using gallium arsenide technology based on spoof surface plasmon polaritons (SSPPs). The proposed structure is developed from traditional half-mode substrate integrated waveguide (HMSIW) and its dispersion characteristics is analyzed through electromagnetic simulations. Consequently, the operating frequency and bandwidth of the on-chip sensor can be easily adjusted, which provides more flexibility for the practical application of the sensor. The linear sensing for relative dielectric constant of the film materials is acquired, with thickness-insensitive property. Moreover, the low coupling to the nearby components can be achieved due to the strong field confinement characteristics of the SSPPs, which is of great significance in the application scenarios of on-chip integrated circuits for the suppression of electromagnetic interference.

Optimal Design Method of High Voltage DC Power Supply EMI Filter Considering Source Impedance of Motor Controller for Electric Vehicle

Passive filters are often used for electromagnetic interference (EMI) suppression on the high voltage (HV) DC side of motor drive systems due to their simple structure and large noise suppression. However, the traditional passive filter design method takes less consideration of the change of the system source impedance, which will lead to almost no insertion loss in some frequency bands or an over-design of the filter. Based on the onboard working conditions of high-voltage and high-current, this article adopts the dual current probe method to obtain the source impedance of the system when it is working, and proposes a filter multi-objective optimization design method based on the genetic algorithm (GA). This method automatically selects the optimal topology of the filter and related component parameters according to the source impedance and load impedance, avoiding the filter resonance phenomenon and over-design problems caused by not considering source impedance. The experimental results show that conducted interference voltage and current of motor drive system with filter designed by the proposed method can pass CISPR25-2016rd level 3.

RF Circuit EMI Suppression and EMC Analysis

The radio frequency circuit will generate strong electromagnetic interference in the process of signal transmission, and its own resistance to electromagnetic interference is weak, and the radio frequency circuits operating in the same electromagnetic environment are prone to mutual interference. Therefore, it is necessary to analyze the electromagnetic interference effect of radio frequency circuits, and then find effective suppression measures, build a good public electromagnetic environment, realize electromagnetic compatibility, and ensure the reliability of signal transmission. This research first briefly introduces electromagnetic interference and electromagnetic compatibility and then analyzes the key points of electromagnetic interference suppression in radio frequency circuits. On this basis, the specific application of electromagnetic interference suppression and electromagnetic compatibility technology of radio frequency circuit is discussed. It can serve as a guide for the design of the radio frequency circuit by analyzing the characteristics and suppression mechanism of the electromagnetic interference of the radio frequency circuit. To ensure the suppression impact of electromagnetic interference, various suppression measures are broadly implemented in accordance with the three components of electromagnetic interference. The electromagnetic compatibility-based design of RF circuits can reduce the mutual interference of RF circuits in the system and guarantee the stability and dependability of signal transmission.

Active EMI Suppression System for a 50 mT Unshielded Portable MRI Scanner.

Passive shielding is usually applied to block electro-magnetic interference (EMI) for portable very-low field MRI scanners, but it goes against the mobility of the scanners. Here, the reference channel-based active EMI suppression (AES) system was proposed to discard them. Different from the existing studies, this work started with analyzing the interference transmission paths and discovered that the human body coupling was the main path. Then, the "ring-" shaped EMI receiving coil designed here together with the electrocardiograph (ECG) electrode patch were used to suppress the human-body-coupled interferences. For the first time, the periphery data of the k-spaces of the RF coil and the EMI detectors were utilized to calculate the transfer factors in multiple frequency bands by using the least square method. The reference EMI signals were transferred to the interferences in the MR signal by multiplying the transfer factors in each frequency band, and the denoised MR signal could be obtained by subtracting the transferred reference EMI signals. The prototype of the AES system was applied to a 50 mT unshielded portable MRI scanner. The in-vivo experiments indicated that the interference suppression rate of the AES system equipped with the "ring-" shaped EMI receiving coil could reach 96.8%. Meanwhile, the SNR of the images after interference suppression by the AES system equipped with both types of detectors was 97.2% of that of the images scanned inside the shielded room. The proposed AES system ensures that the portable MRI scanner works normally in unshielded environment. Our study provides a solution to make portable MRI scanners truly movable.

Space Spread-Spectrum Strategy for MMC to Reduce the Conducted EMI

A modular multilevel converter (MMC) is widely used due to its various advantages. However, it causes serious electromagnetic interference (EMI) problems. Therefore, it is necessary to suppress the conducted EMI of MMC. A novel spread-spectrum (SS) strategy, called space SS (SSS), is proposed in this article. The core idea of the SSS strategy is to make the carrier frequency of each submodule different. The principle and formula derivation of the SSS strategy are elaborated. SSS is a highly free strategy because carrier frequency can be distributed arbitrarily with space position. Several methods for determining carrier frequency distribution are proposed in this article. These methods not only achieve EMI suppression, but also take into account less circulating current, higher switching frequency, and lower switching loss. Total harmonic distortion (THD) and switching loss variation under the SSS strategy are also studied in the article. Experiments are carried out to validate the effectiveness of the SSS strategy. The SSS strategy can reduce the EMI by more than 12 dB and all obvious spikes in the spectrum are eliminated effectively. Besides, it is easy to implement and suitable for practical systems with quantities of submodules.

Research on the Effectiveness of Deep Convolutional Neural Network for Electromagnetic Interference Identification Based on I/Q Data

With the development of wireless communication technology, the electromagnetic interference (EMI) of artificial radio to weather radar increases significantly, which has a serious impact on the quality of radar data. Most of the research on detecting and suppressing electromagnetic interference was based on the primary product of the radar. This paper researches the effectiveness of deep convolutional neural networks (DCNN) to identify and suppress electromagnetic interference based on the I/Q data output from the front end of a radar receiver. Firstly, this paper selected UNet, ResNet with UNet structure, and DeepLab V3+ for the semantic segmentation of electromagnetic interference and other signals. After semantic segmentation, this paper used the linear interpolation method to suppress EMI. Finally, this paper selected the prediction precision of the model and compared the quality of primary products before and after EMI suppression to evaluate the effectiveness of DCNN. The results showed that all three models could effectively identify the electromagnetic interference and the quality of the data were improved after suppression. It suggests that the use of DCNN on the I/Q data output from the front end of a radar receiver can play a certain effect on the identification of electromagnetic interference.