Electromagnetic Simulation Software Research Articles

Magnetic field probe-based co-simulation method for irregular volume-type inductively coupled wireless MRI radiofrequency coils.

Inductively coupled wireless coils are increasingly used in MRI due to their cost-effectiveness and simplicity, eliminating the need for expensive components like preamplifiers, baluns, coil plugs, and coil ID circuits. Existing tools for predicting component values and electromagnetic (EM) fields are primarily designed for cylindrical volume coils, making them inadequate for irregular volume-type wireless coils. The aim of this study is to introduce and validate a novel magnetic (H-) field probe-based co-simulation method to accurately predict capacitance values and EM fields for irregular volume-type wireless coils, thereby addressing the limitations of current prediction tools. The proposed method involves several key steps: modeling the coil in EM simulation software, replacing lumped components with 50-Ω ports, placing well-decoupled double pick-up sniffer probes within the wireless coil, conducting full-wave EM simulations, and exporting the S-parameter matrix to an RF circuit simulation tool for optimization. The RF circuit simulation optimizes component values by maximizing the average magnitude of the root square of Sxys (mean_√Sxy) of double probes and minimizing the normalized standard deviation of √Sxy (normStd_√Sxy). The optimized capacitance values are validated through re-performing EM simulations, and hardware prototypes are fabricated and tested in MRI experiments. The method was validated using bottle-shaped and dome-shaped Litzcage coils designed for 1.5T MRI. Consistent resonant peaks and magnetic field distributions were observed across different coil designs. The optimized capacitance values obtained from circuit-level simulations were confirmed through EM simulations. Significant SNR enhancements were observed in MRI experiments, with the wireless hand and wrist/head coil showing an overall SNR enhancement of 12.8/3.4-fold in EM simulation and 13.4/3.8-fold in MRI experiments, compared to the body coil alone. The H-field probe-based co-simulation method provides an efficient and accurate solution for designing and optimizing irregular wireless RF coils in MRI. By integrating EM simulation, H-field probes, and RF circuit optimization, this method reduces the need for extensive full-wave EM simulations and accurately predicts capacitance values and EM fields. The validation using irregular Litzcage coils demonstrated the method's efficacy, contributing to improved imaging quality in MRI applications. This approach offers a valuable tool for coil developers and researchers, facilitating the development of high-quality irregular wireless coils for enhanced MRI performance.

Research on Opening Reignition Characteristics and Suppression Measures of 750 kV AC Filter Circuit Breakers

The operation of converter valves in converter stations often results in high reactive power consumption and harmonic generation, necessitating measures to maintain reactive power balance and ensure power quality. To achieve this, the filter bank circuit breaker is frequently switched on and off during daily operation. In recent years, multiple incidents of circuit breaker breakdown during the opening process have been reported. In this study, power systems computer-aided design (PSCAD)/electromagnetic transients including DC (EMTDC) V5.0 electromagnetic transient simulation software is used to simulate and calculate the overvoltage and inrush current under different configurations of circuit breaker operating mechanism dispersion, opening phase angle, and operating speed. Additionally, the suppression effects of two measures are compared: “phase selection opening” and “phase selection opening combined with controlled opening speed” to mitigate overvoltage and inrush current. The results demonstrate that for BP11/13 filters, HP24/36 filters, and HP3 filters, the combined strategy of “phase-selective opening with controlled opening speed” is more effective in suppressing inrush current and overvoltage. However, for SC filters, the suppression effect of this combined strategy is not significant. Considering economic and practical factors, it is more reasonable to adopt the phase-selective opening measure for SC filters. These findings provide guidance for ensuring the safe operation of AC filter circuit breakers.

A Low-Coupling Broadband MIMO Array Antenna Design for Ku-Band Based on Metamaterials

In response to the demand for broadband antennas in 5G mobile communications, this paper proposes a compact broadband multiple-input multiple-output (MIMO) antenna array. By chamfering a radiation patch and adding parasitic patches, the antenna is miniaturized while also expanding its bandwidth. The mutual coupling between the two antenna elements is reduced by loading a double-layer metamaterial decoupling structure above the elements which consists of an open resonating ring and a square ring. The antenna is simulated and measured using the three-dimensional electromagnetic simulation software HFSS and a vector network analyzer. The results show that the proposed antenna has a good radiation performance of <i>S</i><sub>11</sub> < -10 dB in the operating band of 12.11–13.99 GHz (relative bandwidth of 14.41%). Furthermore, the isolation of the proposed MIMO antenna array in the operating band is improved by more than -18.8 dB on loading the metameterial structure, indicating that the array antenna is suitable for use in the Ku-band.

Optimal design of novel plasmonic antenna based label free biomedical sensor using Firefly algorithm

The design of a novel plasmonic sensor based on graphene material for label-free sensing applications is presented in this paper. The proposed antenna-based plasmonic sensor is developed on a Polytetrafluoroethylene substrate with a low-profile configuration. The antenna-based sensor has a concentric rhombic configuration with the edges loaded with cross-dipole elements specifically chosen for bandwidth enhancement. The proposed antenna-based sensor operates at 2 THz and 4.6 THz with directional properties. The radiating portions are designed using Graphene while the full ground plane on the rear side is copper-coated to enhance the forward radiation characteristics. The impedance and radiation properties of the antenna are studied theoretically using the electromagnetic simulation software and the optimization using the Firefly algorithm is presented. The optimized antenna exhibited a fractional bandwidth (FBW) of 6 % and 3.4 % at 2 THz and 4.6 THz respectively with reference |S11| ≤ −10 dB. The antenna is subjected to the loading of a dielectric material and the material sensing property is analysed. The proposed sensor with arbitrary dielectric loading offers a sensitivity of 466 GHz/RIU and 1299 GHz/RIU at 2 and 4.6 THz respectively. The antenna-based sensor is tested with analytes, which helps determine various cancer cells, enabling futuristic label-free sensing for healthcare providers.

Influence of fast switching fault current limiter on electromagnetic transient of extra-high voltage transmission line

Abstract The rapid advancement of power systems has led to an increase in short-circuit currents. The short-circuit current can be effectively limited by adding a fast-switching fault current limiter. However, incorporating a current-limiting reactor into ultra-high voltage lines may impact electromagnetic transients. This study utilizes PSCAD/EMTDC electromagnetic transient simulation software to develop a typical 330kV transmission line model for simulation analysis. The paper aims to study whether the current limiting reactor will affect the switching overvoltage in the automatic reclosing overvoltage. The results show that the input of the current-restricting transformer efficiently constrains the magnitude of short-circuit currents and exerts minimal influence on the automatic reclosing overvoltage in ultra-high voltage transmission lines.

Analysis of rotor vibration characteristics of surface mounted permanent magnet synchronous motor under air gap eccentricity fault

Taking a permanent magnet synchronous motor as the research object, the effect of air gap eccentricity fault on the vibration response characteristics of the motor rotor is analyzed through theoretical calculations, numerical simulation and finite element simulation. First, the change of air gap magnetic field under air gap eccentricity fault is analyzed, and then further calculated to obtain the unbalanced magnetic force under air gap fault by the expression of air gap magnetic field, at last, the rotor’s vibration response characteristics under the action of unbalanced electromagnetic force are obtained by the Newmark- β calculation method. Detailed analysis of the effects of eccentricity distance, eccentricity angle and motor pole-pair number on motor rotor vibration. Finally, the synchronous motor eccentricity fault model is built in ANSYS Maxwell electromagnetic simulation software, and the change characteristics of rotor unbalanced magnetic force after eccentricity fault are calculated and the results are consistent with the theoretical calculations.

Artificial Intelligence‐Enhanced Metamaterial Bragg Multilayers for Radiative Cooling

A full numerical study combining artificial intelligence (AI) methods and electromagnetic simulation software on a multilayered structure for radiative cooling (RC) is investigated. The original structure is made of SiO2/Si nanometer‐thick layers that make a Bragg mirror for wavelengths in the solar irradiance window (0.3–4 μm). The structures are then optimized in terms of the calculated net cooling power and characterized via the reflected and absorbed incident light as a function of their structural parameters. This investigation provides with optimal designs of beyond‐Bragg, all‐dielectric, ultra‐broadband mirrors that provide net cooling powers in the order of ≈100 W m−2, similar to the best‐performing structures in literature. Furthermore, it explains AI's success in producing these structures and enables the analysis of resonant conditions in metal‐free multilayers with unconventional layer thickness distributions, offering innovative tools for designing highly efficient structures in RC.

Research on Braking Characteristics of Hybrid Excitation Rotary Eddy Current Retarder

According to the different excitation methods, automotive eddy current retarders (ECRs) can be divided into electrically excited retarders (EERs) and permanent magnet excited retarders (PMERs), and EERs and PMERs have certain complementarity in control and braking characteristics. Therefore, based on literature research, this article proposes a hybrid excitation rotary electromagnetic retarder (HERER) and conducts numerical simulation analysis and experimental research on the braking performance of the HERER. Firstly, the structure and working principle of the HERER are introduced. Secondly, based on the principles of electromagnetics, an equivalent magnetic circuit analysis model of the HERER is established. Then, a finite element analysis model of the HERER is established using Jmag 14 electromagnetic simulation software, and the braking performance of the HERER under different current and speed conditions is studied. Finally, bench tests are conducted on the air loss torque and eddy current braking performance of the HERER. The effectiveness of the finite element analysis model and equivalent magnetic circuit model of the HERER is verified.

Phase gradient metasurface for arbitrary three-dimensional shaped near-field

This paper proposes a methodology for generating arbitrary three-dimensional (3D) shaped near-field using phase gradient metasurface (PGMS) based on phase conjugation (PC) backtracking and shaped diffraction-free Bessel beam array techniques. The PGMS is designed by combining MATLAB and electromagnetic (EM) simulation software (CST). To the knowledge of the authors, for the first time, a 3D-shaped near-field is generated without increasing cost, structural and calculating complexity, and a methodology for generating arbitrarily shaped diffraction-free beam array is developed by MATLAB. To verify the technique, a planar PGMS is designed for dual x-polarized 3D-shaped near-fields: qq image “” in direction (θ1 = 5°, φ1 = 0°) and a flower image “” in direction (θ2 = 10°, φ2 = 180°). The advantages of the 3D-shaped near-fields are as follows: high conversion efficiency 30.5% (measured), wideband 60.5%, and low sidelobe -15 dB. The proposed technique is confirmed by the calculated, simulated, and measured results.

Phase sequence selection method of double-circuit transmission lines on the same tower based on a comprehensive index

Abstract The non-transposition erection of transmission lines will lead to the imbalance of electrical parameters, which will affect the protection and automatic reclosing. The best phase sequence arrangement is determined by comprehensively considering the comprehensive indexes (current imbalance, secondary current, and recovery voltage) of double transmission un-transposed lines with shared towers. PSCAD/EMTDC electromagnetic transient simulation software is applied to build a typical 750kV transmission line model for simulation analysis, and the comprehensive indexes under different phase sequence arrangements are studied. The analysis reveals that the arrangement of phase sequence exerts a significant consequence of the comprehensive index. The findings indicate that the margin and different secondary current and recovery voltage indexes, double transmission un-transposed lines with shared towers can be erected in the same direction or in different phase sequences to reduce the current imbalance.

Analysis of EFT Transmission Characteristics in Armoured Shielded Cables

Abstract Electrical fast transient pulses (EFT) generated when a gas-isolated substation (GIS) is switched on and off. The EFT is transmitted to the control chamber through the secondary control cable, which will cause the failure of the control equipment. In this paper, the three-dimensional electromagnetic simulation software CST (Computer Simulation Technology) is used to study the transmission characteristics of EFT in armored shielded control cables. First, an EFT analog signal is generated using an interference generator. Analyze the difference between the EFT analog signal and the EFT model in the IEC standard. The conversion method of FFT is used to analyze the spectral characteristics of EFT analog signals. According to the structural parameters, a 20-meter-long model of an armored shielded control cable was built in the CST cable studio The effect of the grounding of the shield and armor layers on the attenuation and crosstalk of EFT signals in the cable is studied. Finally, the EFT experiment of 1m long armored shielded cable is carried out, and the reliability of the research method is verified by comparing with the simulation results.

ISAR Imaging Analysis of Complex Aerial Targets Based on Deep Learning

Traditional range–instantaneous Doppler (RID) methods for maneuvering target imaging are hindered by issues related to low resolution and inadequate noise suppression. To address this, we propose a novel ISAR imaging method enhanced by deep learning, which incorporates the fundamental architecture of CapsNet along with two additional convolutional layers. Pre-training is conducted through the deep learning network to establish the mapping function for reference. Subsequently, the trained network is integrated into the electromagnetic simulation software, Feko 2019, utilizing a combination of geometric forms such as corner reflectors and Luneberg spheres for analysis. The results indicate that the derived ISAR imaging effectively identifies the ISAR program associated with complex aerial targets. A thorough analysis of the imaging results further corroborates the effectiveness and superiority of this approach. Both simulation and empirical data demonstrate that this method significantly enhances imaging resolution and noise suppression.

Misalignment‐tolerant coupling cell of 2‐D modular WPT system for charging area simplified extension

Abstract2‐D modular wireless power transfer (WPT) system needs to have stable output when coil misalignment occurs. In order to improve the misalignment tolerance of the system coupling unit, this article proposes a magnetic coupling structure based on the LCC‐S compensation topology by combining a rectangular coil with two sets of mutually orthogonal solenoidal compensation coils. The rectangular coil is used to receive the vertical magnetic flux, and the two sets of compensating coils are used to receive the magnetic flux in the directions of X‐axis and Y‐axis on the horizontal plane, separately. The receiving side of the 2‐D wireless power transmission array cells cascaded half‐bridge rectifiers to connect each group of coils. This arrangement effectively compensates for the voltage drop of the rectangular coil caused by positional offset in any direction, so that the output voltage of the receiving side remains stable. The article firstly establishes the equivalent circuit model of the proposed design and deduces in detail the relationship equations between the output characteristics of the system and each influence factor. Secondly, the magnetic coupling structure is designed by finite element electromagnetic simulation software, and the total equivalent mutual inductance fluctuation of the proposed design is verified to be within 3.9% over the range of 2‐D transmission array cells. Finally, a 150 W experimental platform is built to verify the misaligment‐tolerant of the proposed design in the range of 2‐D transmission array cells. The experimental results show that the output voltage fluctuation of the proposed design within 4.27% at all directional offsets. Moreover, the stable output performance can be obtained in the case of vertical and rotational misalignment.

A Novel 4-port MIMO Antenna with Chamfered Edge for 5G NR n77/n78/n79 Bands and WLAN Applications

Abstract A novel, compact and low-cost four-element multiple-input multiple-output (MIMO) antenna with a high gain is proposed in this work. The suggested antenna structure uses easily accessible substrate material and has been designed and simulated using Ansys HFSS 3D electromagnetic simulation software. The radiating elements are placed orthogonally, and each of them consists of two circular rings. To improve the impedance matching and reduce mutual coupling, the corners are chamfered and partial ground structure is applied. For further enhancement in isolation, Defected Ground Structure (DGS) method is applied which makes the isolation as high as -55 dB. The measured gain of the proposed antenna is more than 12 dB over the considered frequency range. The antenna covers a frequency range from 3.3-6 GHz. The value of diversity gain is found to be more than 9.99 dB and envelope correlation coefficient is less than 0.006 respectively. Also, the mean effective gain, channel capacity loss, and total active reflection coefficient results are within the optimal range. These make the designed antenna suitable for the sub-6 GHz, 5G new radio (NR) n77/n78/n79 where n77 (3.3-4.2 GHz), n78 (3.3-3.8 GHz), and n79 (4.4-5 GHz) bands along with WLAN (5.1-5.8 GHz) applications.

The Supplementary Damping Method for CLCC HVDC Based on Projective Control Theory

This paper proposes a design method for an additional damping reduced-order controller based on the projective control theorem. Improvements are made to the projective theorem to achieve additional damping control through Controllable-Line-Commutated Converter (CLCC)-based High Voltage Direct Current (HVDC), which suppresses low-frequency oscillations. Using small disturbance identification techniques, the system’s linear model is first identified, and the state feedback control law of the system is then determined using the state-space pole assignment control method. Then, by retaining the dominant oscillation modes of the closed-loop system through the improved projective theorem, the state feedback is converted into output feedback. Ultimately, the sixth-order state feedback controller is reduced to a second-order one and applied in the CLCC HVDC additional damping strategy to suppress low-frequency oscillations. Simulation results based on the electromagnetic transient simulation software PSCAD demonstrate that the designed CLCC HVDC additional damping reduced-order projective control exhibits good suppression performance, strong robustness, and low order, which are of significant importance for engineering practice.

Electromagnetic simulation and electromagnetic safety characteristics analysis of implantable medical devices in wireless charging processes

In recent years, wireless charging technology for electric vehicles has received increasing attention. Existing research has been limited to the safety of specific body parts in the electromagnetic environment of wireless charging for electric vehicles, with insufficient consideration for the overall human body and the electromagnetic safety of implanted medical devices. In order to assess its safety in the electromagnetic environment more comprehensively, a three-dimensional electromagnetic simulation software based on the finite element method is used to construct models of the human body and implanted medical devices in the electromagnetic environment of wireless charging for electric vehicles. The study aims to investigate the impact of this electromagnetic environment on the human body and implanted medical devices. The results indicate that, except for the maximum magnetic induction of 0.47 μT at the ankle, which exceeds the limit, the magnetic induction intensity and electric field strength in important tissue areas, especially the upper trunk of the human body, are both below the safety limits specified by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. For implanted cardiac pacemakers, the effective and peak magnetic field strengths are 13.7 A/m and 19.4 A/m, respectively, when the coil input power is 22 kW, meeting the relevant magnetic field strength requirements. The maximum temperature rise of the pacemaker is 3.2 × 10-3∘C, and there are no significant changes in the temperature of the major organs in the human body after the implantation of the pacemaker. The thermal effects of electromagnetic waves on the temperature rise caused by implanted cardiac pacemakers have minimal impact on the human body.

The utility model relates to an L-band slot antenna conformal with a submarine cable

In order to better receive Beidou satellite signals on ships, miniaturized antennas are becoming more and more important. To solve the problem of antenna miniaturization, this paper proposes a novel back cavity slot antenna (CBSA) in conformation with submarine cable. The slot antenna works in the L-band of BDS, adopts parasitic patch structure, and uses HFSS electromagnetic simulation software for simulation and analysis. Results The maximum electric field intensity between the gaps on the surface of the antenna decreased from 854.31V/m to 681.88V/m, and the average gain of the antenna increased by 0.15dB.

Computational analysis of electromagnetic field exposure in passengers near high- current contact wire environments.

The electromagnetic environment of a railway station is composed of electrical, magnetic, and electromagnetic fields, which are generated by various sources such as traction current, voltage, pantograph-catenary arc, locomotive braking, wheel-rail rolling arc, and communication systems. However, there is public growing concern among the public about the potential negative human health effects of this electromagnetic environment. To analyze the distribution of electromagnetic fields in human tissues, electromagnetic simulation software is used to create a model that includes six track contact wires and four waiting passengers on three platforms. This model is used to analyze the magnetic field environment created by high currents in the contact wires of a multi-track high-speed railway station. By varying the loads on different contact wires, the distribution of electric field and magnetic flux density within human tissues of waiting passengers on different platforms is studied using this model. When the track is unoccupied, the calculation results show that the maximum values of the electric field and magnetic flux density of the passenger's human body tissue at the blind way on the platform and 1m of the blind way are 17.6mVm-1 and 52.7 μT, respectively. These values increase by 9.28mVm-1 and 16.4 μT compared to when the track is occupied. When more contact wires are loaded with currents, the electric field mode and magnetic flux density mode of human tissues increase at the same position on the platform. Specifically, when the contact wires of six tracks are loaded with current at the same time, the maximum values of the electric field mode and magnetic flux density mode of the waiting passengers' human tissues at the blind way on different platforms are 29.6mVm-1 and 88.1 μT, respectively. These maximum values are lower than the public electromagnetic exposure limits that are designated by the International Commission on Non-Ionizing Radiation Protection guidelines. The research results demonstrate that the magnetic field environment generated by the current in the contact wires of a railway station with six tracks does not pose a health risk to human tissues of passengers waiting at the blind way and 1m of the blind way on the platform. These findings can provide valuable data reference for the formulation of relevant standards for the design of electrified rail transit, as well as the suppression of electromagnetic interference and protection of human bioelectromagnetism.

Numerical model of the QiTai radio Telescope PAF receiver signal and simulation of interference mitigation

Xinjiang Qitai is constructing a 110-m fully steerable radio telescope (QiTai radio Telescope [QTT]) equipped with a phased array feeds (PAF) receiver, which will install the focal plane operating from 0.7 to 1.8 GHz. In this article, we introduce a PAF receiver model for beamforming, and the numerical model of the internal and external noise for this PAF receiver is provided using electromagnetic field simulation software. The linear constraint minimum variance (LCMV) algorithm is used to simulate the interference mitigation. The interference mitigation rate is from 0.581 to 0.921, and the signal restoration rate is from 0.998 to 1.512 within the error range of an interference arrival angle of 10°. This conclusion can be used in the signal correction of the PAF receiver for interference mitigation.

Two-terminal traveling wave fault location approach based on frequency dependent electrical parameters of HVAC cable transmission lines

With the expansion of high-voltage alternating current transmission networks, the widely used two-terminal traveling wave method faces several challenges in cable fault location. On one hand, the frequency dependent characteristics of longer cable transmission lines can significantly impact the accuracy of traveling wave propagation velocity. On the other hand, the processing of traveling wave signals obtained synchronously is also a crucial factor that requires attention. To enhance the performance of cable fault location, the principles of two-terminal traveling wave method need to be updated. Firstly, the cable model derived from the theory of wave propagation in multi-conductor systems is presented, which reflects the frequency dependent characteristics of the electrical parameters. Whereupon, an innovative cable traveling wave fault location scheme primarily composed of arrival time identification and instantaneous frequency calculation is proposed. Eventually, based on electromagnetic transient simulation software PSCAD/EMTDC, the robustness of the innovative cable fault location method against fault type, fault location, fault resistance, fault initial angle and earth resistivity issues is demonstrated.