Power Converter EMI Analysis Including IGBT Nonlinear Switching Transient Model

It is well known that very high dv/dt and di/dt during the switching instant is the major high-frequency electromagnetic interference (EMI) source. This paper proposes an improved and simplified EMI-modeling method considering the insulated gate bipolar transistor switching-behavior model. The device turn-on and turn-off dynamics are investigated by dividing the nonlinear transition by several stages. The real device switching voltage and current are approximated by piecewise linear lines and expressed using multiple dv/dt and di/dt superposition. The derived EMI spectra suggest that the high-frequency noise is modeled with an acceptable accuracy. The proposed methodology is verified by experimental results using a dc-dc buck converter     

Characterization of power electronics system interconnectparasitics using time domain reflectometry

The significance of interconnect parasitics of power electronics systems is their effects on power converters' electromagnetic interference (EMI)-related performances, such as voltage/current spikes, dv/dt, di/dt, conducted/radiated EMI noise, etc. In this paper, a time domain reflectometry (TDR) measurement-based modeling technique is described for characterizing interconnect parasitics in switching power converters. Experiments are conducted on power components of a prototype high-power inverter, including insulated gate bipolar transistor (IGBT) modules, busbar and bulk capacitors. It is shown that the interconnect inductance of the IGBT module can be extracted completely using TDR. It is also shown that the busbar equivalent circuit can be modeled as transmission line segments or L-C filter sections, and the bulk capacitor contains a significant equivalent series interconnect inductance     

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.     

EMI mitigation with multilayer power-bus stacks and via stitchingof reference planes

General methods for reducing printed circuit board (PCB) emissions over a broad band of high frequencies are necessary to meet EMI requirements, as processors become faster and more powerful. One mechanism by which EMI can be coupled off a PCB or multichip module (MCM) structure is from high-frequency fringing electric fields on the DC power and reference planes at the substrate periphery. An approach for EMI mitigation by stitching multiple ground planes together along the periphery of multilayer PCB power-bus stacks with closely spaced vias is reported and quantified in this paper. Power-bus noise induced EMI and coupling from the board edges is the major concern herein. The EMI at 3 m for different via stitch spacing and layer thickness is modeled with the finite-difference time domain (FDTD) method. Design curves and an empirical equation are extracted from a parametric study to summarize the variation of the radiated EMI as a function of layer thickness and stitch spacing     

Essential-coupling-path models for non-contact EMI in switching power converters using lumped circuit elements

This paper proposes a simple lumped circuit modeling approach for describing noncontact EMI coupling mechanisms in switching power converters. The resulting model assumes a minimum number of noise sources and contains essential coupling paths that allow easy physical interpretations. Essentially, all capacitive couplings are represented by an equivalent noise voltage source and six coupling impedances, whereas all inductive couplings are represented by an equivalent noise current source and three coupling impedances. The resulting coupled noise appears as currents flowing into the terminals of the line-impedance-stabilization-network (LISN). The equivalent voltage source can be conveniently approximated as the switching-node-to-zero voltage, which is typically a rectangular pulse of a few hundred volts. The equivalent current source can be modeled as the current flowing around a loop containing the equivalent voltage source and parasitics such as winding capacitance of the power transformer, the snubber capacitance and connection inductances. Also, the coupling impedances can be estimated by making simplifying assumptions about the geometry of the components and tracks, or by direct measurements. Simulations and experiments verify how inductive and capacitive couplings through each path may produce substantial EMI measured by the LISN. Being based on a lumped circuit approach, the proposed model is easy to apply in practice for understanding, diagnosing and approximating EMI behaviors.     

Noise Source Lumped Circuit Modeling and Identification for Power Converters

In this paper, a general lumped circuit modeling method is proposed to describe the conducted electromagnetic interference (EMI) coupling mechanism for the switching power converters. The EMI characteristics of the converters can be analytically deduced from a circuit theoretical viewpoint. The shunt and series impedance insertion method is introduced to identify the differential-mode (DM) and common-mode (CM) noise impedances and voltage sources. The procedure of parameters estimation for the noise models comprises several simple measurements and is convenient to be implemented. Experimental illustrations are also included to verify the validity of the proposed method. Comparison between the measured and predicted results shows that the EMI modeling method can provide adequate prediction of the EMI feature for power-switching converters     

Characterization and modeling of parasitic emission in deep submicron CMOS

This paper presents a study of the parasitic emissions of a 0.18-/spl mu/m CMOS experimental integrated circuit (IC) and an accurate method for modeling the internal current switching to forecast electromagnetic interference (EMI). The effectiveness of emission reduction techniques is quantified through a set of conducted noise measurements. A simple core model is developed, based on the current switching activity. Added to a lumped-element model of the test board and the package, good agreement between simulation and measurements are obtained up to 10 GHz. The simulation methodology may be applied to forecast the impact of low emission design techniques on the EMI of ICs.     

FDTD modeling incorporating a two-port network for I/O line EMIfiltering design

Electromagnetic interference (EMI) filters are often utilized on I/O lines to reduce high-frequency noise from being conducted off the printed circuit board (PCB) and causing EMI problems. The filtering performance is often compromised at high frequencies due to parasitics associated with the filter itself, or the PCB layout and interconnects. Finite difference time domain (FDTD) modeling can be used to quantify the effect of PCB layout and interconnects, as well as filter type, on the EMI performance of I/O line filtering. FDTD modeling of a T-type and π-type filter consisting of surface-mount ferrites and capacitors is considered herein. The FDTD method is applied to model PCB layout and interconnect features, as well as the lumped element components, including the nonlinear characteristics of ferrite surface-mount parts. The EMI filters with ferrites; are included in the modeling by incorporating the time-domain Y-parameters of the two-port network into the FDTD time-marching equations. Good agreement between the FDTD modeling and S-parameter measurements supports the new FDTD algorithm for incorporating two-port networks     

High-performance inter-PCB connectors: analysis of EMIcharacteristics

Electromagnetic interference (EMI) coupling associated with inter-board connection is investigated. Two experimental techniques, based on |S₂₁| measurements, including both common-mode current and near-field measurements, are reported. Both methods, as well as finite difference time domain (FDTD) modeling, were used as experimental and numerical tools for inter-printed-circuit-board (inter-PCB) connector evaluation. The EMI performance of a lab-constructed stacked-card connector, and a commercially available module-on-backplane connector were studied. EMI characteristics of the connectors are demonstrated by investigating a few aspects of the design: type of shield/ground blade for signal return, number and length of ground pins, signal pin designation, etc. Good agreement is achieved between the measurements and the FDTD modeled results     

基于新能源利用的逆变系统电磁干扰噪声解决方案

文章在对线性阻抗稳定网络内部结构和测量原理分析的基础上,针对于新能源系统的传导电磁干扰问题提出一种新的测量方法。利用该方法可以较为精确的测量新能源系统中逆变系统的传导电磁干扰噪声,并设计相应的滤波器对于传导电磁干扰噪声进行抑制。并且,根据新能源的特点,提出在直流侧加入电感电容以稳定由于直流侧电能不稳定所带来的电磁干扰噪声问题。实验结果表明该方法较为有效。     

A statistical approach to landmine detection using broadbandelectromagnetic induction data

The response of time-domain electromagnetic induction (EMI) sensors, which have been used almost exclusively for landmine detection, is related to the amount of metal present in the object and its distance from the sensor. Unluckily, there is often a significant amount of metallic clutter in the environment that also induces an EMI response. Consequently, EMI sensors employing detection, algorithms based solely on metal content suffer from large false alarm rates. To mitigate this false alarm problem for mines with substantial metal content, statistical algorithms have been developed that exploit models of the underlying physics. In such models it is commonly assumed that the soil has a negligible effect on the sensor response, thus the object is modeled in "free space." We report on studies that were performed to test, the hypotheses that for broadband EMI sensors: 1) soil cannot be modeled as free space when the buried object has low metal content and 2) advanced signal processing algorithms can be applied to reduce the false alarm rates. Our results show that soil cannot be modeled as free space and that when modeling soil correctly our advanced algorithms reduced the false alarm probability by up to a factor of 10 in blind tests     

A passive lossless snubber cell for nonisolated PWM DC/DCconverters

A passive lossless snubber cell is proposed to improve the turn-on and turnoff transients of the MOSFETs in nonisolated pulsewidth modulated (PWM) DC/DC converters. Switching losses and EMI noise are reduced by restricting di/dt of the reverse-recovery current and dv/dt of the drain-source voltage. The MOSFET operates at zero-voltage-switching (ZVS) turnoff and near zero-current-switching (ZCS) turn-on. The freewheeling diode is also commutated under ZVS. As an example, operation principles, theoretical analysis, relevant equations, and experimental results of a boost converter equipped with the proposed snubber cell are presented in detail. Efficiency of 96% has also been measured in the experimental results reported for a 1 kW 100 kHz prototype in the laboratory, Six basic nonisolated PWM DC/DC converters (buck, boost, buck-boost, Cuk, Sepic, and Zeta) equipped with the proposed general snubber cells are also shown in this paper     

A systematic coupled approach for electromagnetic susceptibility analysis of a shielded device with multilayer circuitry

This paper presents a systematic coupled approach for electromagnetic susceptibility (EMS) analysis of a shielded electronic device in the presence of an ambient electromagnetic interference (EMI). A full-wave electromagnetic modeling technique coupled with a circuit-based method is developed for the overall EMS performance analysis. The mixed-potential electric field integral equation (MPIE) is formulated via the method of moments to model the electromagnetic properties of an arbitrary structure consisting of wires and surfaces with any applied excitation. With numerical analysis, the effect of an ambient electromagnetic noise is characterized, and an equivalent circuit model is extracted for further analysis of EMI to internal high-speed sensitive circuits. Numerous examinations exhibit that this systematic coupled approach is a computationally efficient method to address the EMS problems at system level, in which the external EMI effects are fully considered and the circuit-based simulator is also exploited.     

A Suitable Method for Ecovehicles to Control Surge Voltage Occurring at Motor Terminals Connected to PWM Inverters and to Control Induced EMI Noise

A method that is suitable for ecovehicles, which controls the surge voltage appearing at motor terminals that are connected to a pulsewidth modulation inverter with short leads that are less than the critical cable length (i.e., the shortest length at which full reflection may occur), is described here. Also, a method to control electromagnetic interference (EMI) noise, which is induced by the surge voltage, is discussed. Ecovehicles have the problem where insulation degradation of motors occurs due to the surge voltage being repeatedly applied to motor terminals during long lifecycles. EMI noise such as the shaft current and the radiated noise, which are induced by the generated surge voltage, easily diffuse into other electric devices due to the high-density packaging structure. The diffused EMI noise may cause a malfunction of the vehicle controller. An EMI noise controller is studied, which can meet the high-density packaging requirements for ecovehicles like electric vehicles. The EMI noise controller is attached on the motor terminals and simultaneously suppresses the surge voltage and the noise. After clarifying surge voltage characteristics and a circuit model for expressing the surge phenomenon through experiments and simulations, an EMI noise controller is proposed, which uses a multilayer printed power circuit technique. It is verified through simulations and experiments that the proposed controller has the ability to simultaneously control the surge voltage and the EMI noise, such as the radiated noise and the shaft current (the bearing current), which are induced by the surge voltage.     

Cross validation for selection of cortical interaction models from scalp EEG or MEG

A cross-validation (CV) method based on state-space framework is introduced for comparing the fidelity of different cortical interaction models to the measured scalp electroencephalogram (EEG) or magnetoencephalography (MEG) data being modeled. A state equation models the cortical interaction dynamics and an observation equation represents the scalp measurement of cortical activity and noise. The measured data are partitioned into training and test sets. The training set is used to estimate model parameters and the model quality is evaluated by computing test data innovations for the estimated model. Two CV metrics normalized mean square error and log-likelihood are estimated by averaging over different training/test partitions of the data. The effectiveness of this method of model selection is illustrated by comparing two linear modeling methods and two nonlinear modeling methods on simulated EEG data derived using both known dynamic systems and measured electrocorticography data from an epilepsy patient.     

S-parameter based technique for simultaneous switching noiseanalysis in electronic packages

A method based on S-parameters is developed for the analysis of simultaneous switching noise (SSN) in electronic packages. A two-port Z matrix of the package pin/trace, and the coupling between the pins/traces are modeled by analytical equations. SSN is analyzed as a function of the number of switching drivers and switching time. Frequency domain measurements are performed to demonstrate the accuracy of the model. The modeling methodology is applied to both leaded and area array packages     

Macromodeling of nonlinear digital I/O drivers

In this paper, a modeling technique using spline functions with finite time difference approximation is discussed for modeling moderately nonlinear digital input/output (I/O) drivers. This method takes into account both the static and the dynamic memory characteristics of the driver during modeling. Spline function with finite time difference approximation includes the previous time instances of the driver output voltage/current to capture the output dynamic characteristics of digital drivers accurately. In this paper, the speed and the accuracy of the proposed method is analyzed and compared with the radial basis function (RBF) modeling technique, for modeling different test cases. For power supply noise analysis, the proposed method has been extended to multiple ports by taking the previous time instances of the power supply voltage/current into account. The method discussed can be used to capture sensitive effects like simultaneous switching noise (SSN) and cross talk accurately when multiple drivers are switching simultaneously. A comparison study between the presented method and the transistor level driver models indicate a computational speed-up in the range of 10-40 with an error of less than 5%. For highly nonlinear drivers, a method based on recurrent artificial neural networks (RNN) is discussed.     

一种集成RC吸收器的低EMI分离栅VDMOS

为满足高速、高集成度和低EMI的要求,提出了一种分离栅VDMOS器件。通过在JFET区集成梳状MOS电容、漂移区电阻,构成内部集成RC吸收器,减小了器件关断过程中漏端电压斜率dV_ds/dt和电流斜率dI_d/dt。仿真结果表明,相比于常规VDMOS,该VDMOS的漏端过冲电压从535 V降低到283 V,抖动频率从42 MHz降低到33 MHz,抖动持续时间从65 ns缩短到30 ns。     

A low-inductance line-frequency commutated rectifier complying with EN 61000-3-2 standards

This paper presents a high power factor rectifier, based on a modified conventional rectifier with passive L-C filter, which utilizes a line-frequency-commutated switch and a small auxiliary circuit in order to improve both harmonic content of the input current and power factor, thus allowing compliance with EN 61000-3-2 European standards. Being the switch turned on and off only twice per line period, the associated losses are very small. Moreover the limited di/dt and dv/dt considerably reduce the high-frequency noise emission, thus avoiding heavy EMI filters. The switch operation results in a boost action, which compensates for the filter inductor voltage drop, thus providing output voltage stabilization against load variations. Compared with other similar approaches, the presented topology can achieve higher power levels with a reasonable overall magnetic component size.     

Iterative and sequential algorithms for multisensor signalenhancement

In problems of enhancing a desired signal in the presence of noise, multiple sensor measurements will typically have components from both the signal and the noise sources. When the systems that couple the signal and the noise to the sensors are unknown, the problem becomes one of joint signal estimation and system identification. The authors specifically consider the two-sensor signal enhancement problem in which the desired signal is modeled as a Gaussian autoregressive (AR) process, the noise is modeled as a white Gaussian process, and the coupling systems are modeled as linear time-invariant finite impulse response (FIR) filters. The main approach consists of modeling the observed signals as outputs of a stochastic dynamic linear system, and the authors apply the estimate-maximize (EM) algorithm for jointly estimating the desired signal, the coupling systems, and the unknown signal and noise spectral parameters. The resulting algorithm can be viewed as the time-domain version of the frequency-domain approach of Feder et al. (1989), where instead of the noncausal frequency-domain Wiener filter, the Kalman smoother is used. This approach leads naturally to a sequential/adaptive algorithm by replacing the Kalman smoother with the Kalman filter, and in place of successive iterations on each data block, the algorithm proceeds sequentially through the data with exponential weighting applied to allow adaption to nonstationary changes in the structure of the data. A computationally efficient implementation of the algorithm is developed. An expression for the log-likelihood gradient based on the Kalman smoother/filter output is also developed and used to incorporate efficient gradient-based algorithms in the estimation process