基于小波分析的电磁干扰测量技术研究

该文提出了一种新颖的可在开阔场快速测试受试设备的电磁干扰的数字信号处理技术。利用小波变换对测试信号分频滤波处理,可以在被环境噪声污染的地方进行受试设备的电磁辐射干扰测试。基于小波分析的阈值函数滤波方法得到应用。利用小波分析时频都可局部化的特点计算出环境噪声的相关性,提取出噪声的时频特性,并由给出的阈值函数对噪声滤除或者衰减,得到受试设备的实际电磁辐射信号。测试方法使得受试设备不必进入暗室即可进行电磁辐射干扰测量,既节省了测试费用又方便了受试设备的电磁干扰测试。系统运行结果证明此方法在30 Hz~1000 MHz的频段内成功衰减并滤除了环境噪声。     

Circuit analysis of electromagnetic radiation and field couplingeffects for networks with embedded full-wave modules

With continually increasing operating frequencies, the analysis of electromagnetic interference (EMI)-related effects is becoming an important issue for high-speed designs. An algorithm is presented for fast analysis of radiation and incident field coupling effects in high-speed circuits. The proposed technique provides an efficient means for combining the solutions from full-wave field solvers such as the finite-difference time-domain (FDTD) method with circuit level simulators such as SPICE for calculating radiated/coupled fields in arbitrarily shaped interconnect structures. The technique speeds up the whole simulation process by employing a model-reduction-based approach, and also overcomes the numerical stability problems associated with the FDTD, in the presence of nonlinear terminations. In addition, the proposed algorithm provides a direct access to existing vast device libraries of SPICE in EMI analysis     

Efficient analytical formulation and sensitivity analysis of neuro-space mapping for nonlinear microwave device modeling

A new computer-aided design (CAD) method for automated enhancement of nonlinear device models is presented, advancing the concept of Neuro-space mapping (Neuro-SM). It is a systematic computational method to address the situation where an existing device model cannot fit new device data well. By modifying the current and voltage relationships in the model, Neuro-SM produces a new model exceeding the accuracy limit of the existing model. In this paper, a novel analytical formulation of Neuro-SM is proposed to achieve the same accuracy as the basic formulation of Neuro-SM (known as circuit-based Neuro-SM) with much higher computational efficiency. Through our derivations, the mapping between the existing (coarse) model and the overall Neuro-SM model is analytically achieved for dc, small-signal, and large-signal simulation and sensitivity analysis. The proposed analytical formulation is a significant advance over the circuit-based Neuro-SM, due to the elimination of extra circuit equations needed in the circuit-based formulation. A two-phase training algorithm utilizing gradient optimization is also developed for fast training of the analytical Neuro-SM models. Application examples on modeling heterojunction bipolar transistor (HBT), metal-semiconductor-field-effect transistor (MESFET), and high-electron mobility transmistor (HEMT) devices and the use of Neuro-SM models in harmonic balance simulations demonstrate that the analytical Neuro-SM is an efficient approach for modeling various types of microwave devices. It is useful for systematic and automated update of nonlinear device model library for existing circuit simulators.     

Fast EMI Analysis via Transverse Partitioning and Waveform Relaxation

High-speed interconnects are increasingly becoming susceptible to electromagnetic interference (EMI). Hence, there is a growing need for fast simulation of interconnect lines in the presence of incident field coupling using circuit simulators such as SPICE. However, the presence of a large number of coupled lines in modern interconnect structures is a serious limiting factor in these simulations. In order to simultaneously address these difficulties, a new algorithm is presented in this paper for EMI analysis of large number of coupled interconnects. The new method exploits the recently developed waveform relaxation (WR) and transverse partitioning algorithms for fast EMI analysis. The same WR sources that are computed for multiconductor transmission line analysis are also employed for EMI analysis. The computational complexity of the proposed EMI analysis grows only linearly with the number of lines. In addition, the algorithm lends itself to parallel implementation leading to further reduction in CPU time.      

Field-Line-Circuit Coupling Based Method for Predicting Radiated Electromagnetic Emission of IGBT-PMSM Drive System

Electric drive system with Insulated gate bipolar transistor (IGBT) power device is widely used in Electric vehicle (EV), which consists of inverter, cables and Permanent magnet synchronous motor (PMSM). Due to the fast switching in di/dt and dv/dt of IGBT device, the system produces serious radiated Electromagnetic interference (EMI) through the interconnection cables. Thus, modeling of EMI source, propagation path and load PMSM is the key to accurately evaluate the system's radiation level. In addition, the system's radiated EMI involves the integrated calculation of circuit, cable and electromagnetic field, which cannot be solved by using a single circuit or electromagnetic calculation method. Therefore, this paper develops an effective field-linecircuit coupling based method to investigate the radiated EMI problems for IGBT-PMSM drive system, which is validated by experimental measurement. Besides, the impact of power cable parameters on radiated EMI is discussed. The proposed approach has guiding significance for electromagnetic compatibility design of EV.     

CRT 显示器电磁敏感性初探

采用大电流注入（BCI）的试验方法对计算机用CRT 显示器的电磁敏感性（EMS）进行研究。试验中,将某一频率下不同幅度的连续波信号作为电磁干扰信号注入到VGA 接口的RGB、水平同步（HS）、垂直同步（VS）信号线中。当HS 信号线中注入干扰信号时,CRT 出现斜条纹这一电磁敏感现象,电磁干扰信号越强,斜条纹越明显,而RGB、VS 信号 线注入时,则没有出现上述现象。此外,还研究了注入信号与HS 信号线耦合信号的关系。     

Electromagnetic susceptibility characterization of double SOI device

Under a research project of monolithic pixel detectors, a double silicon on insulator (DSOI) structure was introduced based on fully depleted SOI (FDSOI) technology. It not merely integrates the sensor and readout circuit on the same processed wafer, but also increases radiation tolerance. Electromagnetic susceptibility (EMS) is also an important reliability issue in pixel detectors. The readout circuit should avoid false signal generation due to coupled noise from the substrate. This paper evaluates the performance of DSOI devices regarding total ionizing dose (TID) effect compensation in transistors by applying a negative bias to the middle silicon layer, and evaluates the electromagnetic susceptibility of the substrate by a ring oscillator. The experiment results show that the DSOI device is able to compensate for TID, and the threshold voltage and leakage current are recoverable. However, the reduction of TID effect on the DSOI device is at the expense of increasing susceptibility to electromagnetic interference (EMI) on the substrate.     

Multiple Slope Switching Waveform Approximation to Improve Conducted EMI Spectral Analysis of Power Converters

An improved and simplified electromagnetic interference (EMI) modeling method based on multiple slope approximation of device-switching transitions for EMI analysis of power converters is presented. The traditional noise source modeling method, which uses single slope for rise and fall transition, is studied, and the criteria for reasonable modeling in the frequency range is analyzed. The turn-on and turn-off dynamics are investigated by dividing the nonlinear transitions into several stages based on an insulated gate bipolar transistor (IGBT) behavior circuit model. Real device-switching voltage and current waveforms are approximated by piece-wise linear lines and modeled by multiple dv/dt and di/dt slopes. The predicted EMI spectra suggest that high-frequency EMI noise is modeled with an acceptable accuracy. The proposed method was verified experimentally for a dc-dc buck converter     

Circuit-based versus full-wave modelling of active microwave circuits

Modern full-wave computational tools enable rigorous simulations of linear parts of complex microwave circuits within minutes, taking into account all physical electromagnetic (EM) phenomena. Non-linear components and other discrete elements of the hybrid microwave circuit are then easily added within the circuit simulator. This combined full-wave and circuit-based analysis is a must in the final stages of the circuit design, although initial designs and optimisations are still faster and more comfortably done completely in the circuit-based environment, which offers real-time solutions at the expense of accuracy. However, due to insufficient information and general lack of specific case studies, practitioners still struggle when choosing an appropriate analysis method, or a component model, because different choices lead to different solutions, often with uncertain accuracy and unexplained discrepancies arising between the simulations and measurements. We here design a reconfigurable power amplifier, as a case study, using both circuit-based solver and a full-wave EM solver. We compare numerical simulations with measurements on the manufactured prototypes, discussing the obtained differences, pointing out the importance of measured parameters de-embedding, appropriate modelling of discrete components and giving specific recipes for good modelling practices.     

Time-Domain Investigation on Cable-Induced Transient Coupling Into Metallic Enclosures

A hybrid time-domain method is proposed for characterizing electromagnetic interference (EMI) signals coupled into some composite structures with metallic enclosures, braided shielded cable, printed circuit boards, and even lumped active devices. In order to rapidly capture the induced interior EMI, the finite-difference time-domain, modified node analysis, and multiconductor transmission lines methods are combined together and implemented successfully. Numerical investigation is carried out to demonstrate the frequency-dependent transfer impedance of the coaxial cable, the induced voltage at the place of active loaded element in the transmission line network, and the enclosure shielding effectiveness of these composite enclosures. The captured transient response information is useful for further designing electromagnetic protection of the inner circuits against the impact of voltage or current surge caused by nonintentional as well as intentional electromagnetic interference.      

直升机中电磁耦合薄弱路径的确定方法

直升机结构复杂、空间狭小、设备繁多,从而导致全机电磁环境异常复杂。为了快速定位全机电磁干扰耦合的通道,该文提出一种电磁干扰耦合薄弱路径的确定方法。它通过将复杂电磁干扰耦合网络转换成电磁干扰耦合有向图,以电磁能量衰减量最小为基础,在指定频点处使用Dijkstra算法寻找出干扰源和敏感点之间的最短路径,从而确定电子系统的薄弱环节。使用该方法对直升机某处理机和电台系统进行了仿真分析,并成功地寻找出敏感设备受扰的主要耦合通道。仿真和分析表明该方法可有效地寻找出系统电磁耦合的薄弱环节,并为系统的电磁兼容问题提供支撑。     

Microcontroller susceptibility variations to EFT burst during accelerated aging

With deterioration of the electromagnetic environment, microcontroller unit (MCU) electromagnetic susceptibility (EMS) to transient burst interference has become a focus of academia and enterprise. Most electromagnetic compatibility (EMC) studies of MCUs have not taken the effects of aging into account. However, component aging can degrade the physical parameters of an MCU and change its immunity to EMI. This paper proposes a time-equivalent interval accelerated aging methodology combining DC electrical and high temperature stresses. The test results show variations in susceptibility to electrical fast transients (EFT) burst revealing increasing susceptibility. The reasons for MCU immunity drifts in the aging process are discussed.     

Analysis of electromagnetic radiation from a video output amplifierinside a monitor by using FDTD method

The finite-difference time-domain (FDTD) method is used to analyze the electromagnetic compatibility and interference (EMC and EMI) problems due to the electromagnetic radiation from a video output amplifier located inside a computer monitor. The multiple grid technique is implemented in the FDTD method to improve the computational efficiency. The video output amplifier is modeled by a rectangular iron container with an equivalent dipole antenna located at the center of one opened wall facing the cathode-ray-tube (CRT). The coupled electric fields inside and outside the monitor are calculated. It is found that higher values of coupled electric fields occur near the monitor screen. It is also found that the coupled electric fields outside the CRT region drop sharply in amplitude. Simulation results of coupled electric fields at a distance of 3 m from the monitor screen also comply with the FCC regulations. Calculation results also agree with the experimental data for coupled electric fields outside the monitor screen at a measured distance of 3 m     

场线路多耦合下电机及其驱动系统辐射电磁干扰预测方法研究

本文研究了场线路多耦合下电机及其驱动系统辐射电磁干扰预测方法.共模干扰回路是系统产生电磁辐射的主要来源,分析了系统共模干扰源的产生机理和传导路径.建立了共模干扰传导路径中主要部件的模型,即交流感应电机等效电路模型及驱动系统输入输出屏蔽电缆线束模型等,将各部分电路模型按照实际连接情况进行组合,获得了系统辐射电磁干扰预测模型.提出了利用CST MWS和CST CS对预测模型联合仿真的分析方法,并通过实验验证了预测模型的正确性.     

平流层空中信息平台中电机电磁干扰研究

研究平流层空中信息平台的电磁兼容问题具有十分重要的意义.以平台中的伺服电机发生火花放电时对外造成的电磁辐射为主要干扰源,建立了电磁干扰的物理模型,并通过仿真计算分析了平流层空中信息平台的电磁干扰分布及其对平台上所用通讯天线阵的影响.为平流层空中信息平台的系统设计提供了有效的指导.     

Impact of Switching-Induced Electromagnetic Interference on Low-Voltage Cables in Substations

The electromagnetic environment within a substation is very complex. Substations represent an intricate interconnected collection of devices that serve as electromagnetic wave emitters and receptors. Transient electromagnetic emissions—electromagnetic interference (EMI)—are generated during the switching of disconnector and circuit breakers (CBs) that may cause malfunction or damage to electronic equipment positioned nearby if appropriate immunity measures are not taken. The interference may couple significant energy through common-mode currents to cable protection. Electromagnetic compatibility is mostly achieved by addressing the EMI victim through techniques in the secondary environment, such as shielding and filtering. This paper presents the finite-element method analysis of three methods: metallic channel, braided cable, and additional cable, used for EMI mitigation on low-voltage cables of 20 kV side in a 63-kV/20-kV substation due to switching effects of disconnector and CBs. In each method, overvoltage is considered and the results are compared with each other. A simple circuit analysis was also carried out on the causes of switching based on EMI to provide some insight into the interference mechanism during switching process, using common-mode and differential-mode equivalent circuits. The overvoltage reductions are attained through differential-mode current and shielding methods.      

Fast and Rigorous Analysis of EMC/EMI Phenomena on Electrically Large and Complex Cable-Loaded Structures

A fast and comprehensive time-domain method for analyzing electromagnetic compatibility (EMC) and electromagnetic interference (EMI) phenomena on complex structures that involve electrically large platforms (e.g., vehicle shells) along with cable-interconnected antennas, shielding enclosures, and printed circuit boards is proposed. To efficiently simulate field interactions with such structures, three different solvers are hybridized: (1) a time-domain integral-equation (TDIE)-based field solver that computes fields on the exterior structure comprising platforms, antennas, enclosures, boards, and cable shields (external fields); (2) a modified nodal-analysis (MNA)-based circuit solver that computes currents and voltages on lumped circuits approximating cable connectors/loads; and (3) a TDIE-based transmission line solver that computes transmission line voltages and currents at cable terminations (guided fields). These three solvers are rigorously interfaced at the cable connectors/loads and along the cable shields; the resulting coupled system of equations is solved simultaneously at each time step. Computation of the external and guided fields, which constitutes the computational bottleneck of this approach, is accelerated using fast Fourier transform-based algorithms. Further acceleration is achieved by parallelizing the computation of external fields. The resulting hybrid solver permits the analysis of electrically large and geometrically intricate structures loaded with coaxial cables. The accuracy, efficiency, and versatility of the proposed solver are demonstrated by analyzing several EMC/EMI problems including interference between a log-periodic monopole array trailing an aircraft's wing and a monopole antenna mounted on its fuselage, coupling into coaxial cables connecting shielded printed circuit boards located inside a cockpit, and coupling into coaxial cables from a cell phone antenna located inside a fuselage.     

A high EMS daisy-chain SPI interface for battery monitor system

A high EMS current-mode SPI interface for battery monitor IC (BMIC) is presented to form a daisy-chain bus configuration for the cascaded BMICs and the communication between the MCU and master BMIC. Based on analog and digital mixed filtering technique, the proposed daisy-chain can avoid the isolated communication issue in electromagnetic interference environment, and reduce the extensively required I/O ports of MCU, at the same time reduce the system cost. The proposed daisy-chain interface was introduced in a 6-ch battery monitor IC which was fabricated with 0.35 μm 30 V BCD process. The measurement result shows that the presented daisy-chain SPI interface achieves better EMS performance with different EMI injection while just consuming a total operation current up to 1 mA.     

电磁干扰滤波器的参数及其测试

EMI滤波器作为抑制电磁干扰的最有力的手段,日益为人们所了解和广泛使用。对EMI滤波器的理解、应用及测试技术的掌握就变得十分重要。文章介绍EMC常用组件,讨论常用的滤波器的分类及选择,重点介绍EMI滤波器的测试指标和标准,分析EMI滤波器的测试方法.     

Measurement of EMI on network cables due to multiple GSM phones

As the density of transmitters from mobile telecommunication systems continues to increase there is a greater risk of electromagnetic compatibility (EMC) problems due to the ensemble electromagnetic field from multiple mobile handsets. An analysis of the characteristics of the threat field from multiple handsets is presented allowing prediction of the statistics of the ensemble field. A measurement system designed to detect electromagnetic interference (EMI) from ensembles of cellular phones has been used to quantify the level of EMI on Ethernet cables from multiple global system for mobile communications (GSM) mobiles. The measurements are consistent with a simple statistical model of ensemble signals from GSM sources and electromagnetic modeling of the system