Electromagnetic Interference Receiver Research Articles

Output DM EMI Noise Prediction for MHz TCM-Based Single Phase Inverter

Conventional fast Fourier transform analysis is limited in conducted electromagnetic interference (EMI) prediction for triangle current mode (TCM) based converters. Several prediction strategies based on EMI receiver modeling have been published for this issue, but the prediction range was below 1 MHz. Such a narrow frequency range cannot meet the demands of EMI prediction for MHz converter. In this article, a more accurate differential mode (DM) EMI prediction is proposed for MHz TCM-based single-phase inverter. The accurate drain-to-source voltage model considering the TCM resonant transition is established for different TCM-derived strategies at first. Passive components of the propagation path are also modeled with the measured impedance for more accurate transfer gain. An improved envelope detector model of the EMI receiver is proposed for an accurate quasi-peak spectrum. The prediction range can be extended to 5 MHz. Moreover, the EMI of TCM, hybrid triangle current mode, and sinusoidal triangle current mode are analyzed and compared with the established prediction strategy. The worst spectrum can be determined, and the DM filter can be designed without repetitive measurements. Finally, A 500 W MHz single-phase inverter prototype is built, and the evaluation of the measured conducted EMI spectrum and the EMI filter design can verify the theoretical analysis.

EMI 사전 적합성 검증을 위한 시뮬레이션을 이용한 EMI Receiver 설계

본 논문은 EMI(Electromagnetic Interference) 사전 적합성 검증을 위한 시뮬레이션을 이용한 EMI Receiver 설계를 제안한다. EME(Electromagnetic Emission)는 EMC(Electromagnetic compatibility) 규격에 따라 제한되며, 제품으로 출시되는 전자기기는 적합성 검증 시험을 통과해야 한다. EMI 적합성 검증에서 발생할 수 있는 문제를 빠르게 사전에 차단할 수 있는 사전 적합성 검증은 매우 중요하다. 본 논문에서는 Matlab를 이용하여 CISPR-16 규격에 맞는 RBW(Resolution Bandwidth) Filter를 설계하고 EMI receiver시뮬레이션 모델링하여 사전 적합성 검증을 진행하였다. 그 결과 다양한 규격에서 사용할 수 있는 EMI receiver 시뮬레이션 모델을 설계하였으며, EMI receiver를 이용한 FFT(Fast Fouier Transform), Peak, Average 시뮬레이션 결과를 제시하였다.

Prediction of EMI Filter Attenuation in Power-Electronic Converters via Circuit Simulation

This article investigates the conducted-emission (CE) suppression characteristics of electromagnetic interference (EMI) filters used in power-electronic equipment by time-domain circuit simulation. An operational definition of insertion attenuation is introduced by comparing the CE in the absence and in the presence of the EMI filter. For the sake of exemplification, the analysis focuses on switched-mode dc–dc converters. It is shown that the EMI-filter attenuation behaves differently from the standard insertion loss (IL) and exhibits peculiar properties in these circuits. Namely, its response is known at discrete frequencies where the converter generates CE and may strongly depend on the harmonic index so to jump between quite different levels from a harmonic component to the next one, with a pseudoperiodic behavior, which can be related to the duty cycle. This effect is caused by circuit nonlinearity and is partially mitigated if the simulation accounts for two practically relevant aspects: random instability of the duty cycle and resolution bandwidth of the EMI receiver. The dependence of the common-mode (CM) and differential-mode attenuations on the loading conditions and duty cycle is analyzed, and it is shown that linear IL models provide reasonable predictions of CM attenuation only. Finally, experimental evidence of the unveiled phenomena is presented.

The Influence of Driving Parameters on Conducted EMI for an IGBT Module

Insulated gate bipolar transistor (IGBT) has been widely used in the voltage-source-converter-based high-voltage direct current (VSC-HVDC). However, the electromagnetic interference (EMI) generated by its fast switching process affects the normal operation of the surrounding power equipment. The switching voltage and current of IGBT are the main sources of EMI. Different driving circuit parameters result in different IGBT switching characteristics. In this article, the switching model of IGBT is introduced first and the influence of driving parameters on EMI sources is analyzed. Based on the conducted EMI experiment platform of an IGBT module, the time-domain waveforms of switching voltage and current under different driving parameters are obtained and compared with the model. Then the interference voltage spectrums are measured by an EMI receiver under different driving parameters. The influence of driving parameters on conducted EMI in 0.15–30 MHz is then analyzed and explained by combining the result of time domain and frequency domain. This article comprehensively analyzes the relationship between driving parameters and EMI sources and summarizes the influence characteristics of driving parameters on common-mode (CM) and differential-mode (DM) noise. The conclusions can help the parameters design of driving board, which can effectively reduce the conducted EMI of the converter.

Time‐domain low‐frequency non‐periodic transient EMI measurement system

In this study, a time-domain low-frequency non-periodic transient electromagnetic interference (EMI) measurement system is presented. By the use of an antenna, an anti-aliasing filter, and a digital oscilloscope, the radiated emissions measurement specified by electromagnetic compatibility standard MIL-STD-461 is achieved. In the first stage, the antenna receives the radiated emissions of the device under test and the time domain output voltage is acquired in the oscilloscope. Then, to fulfil the spectrum measurement as accurate as an EMI receiver, a spectrum calculating methodology is carried out. Optimised inverse fast Fourier transform procedure for spectrum estimation in the proposed methodology is implemented to reduce the calculation efforts. The proposed EMI measurement technique required only a single time-domain acquisition and no repeatedly continuous scanning was imposed on the frequency measurement of the EMI test receivers. Due to this benefit, scan times are decreased by several orders of magnitude in comparison with a traditional EMI receiver.

Time‐domain virtual EMI receiver model algorithm for corona‐originated electromagnetic interference of dc transmission line

A time-domain virtual electromagnetic interference (EMI) receiver model algorithm for corona-originated EMI of dc transmission line is proposed. The presented model is based on short-time fast Fourier transform (FFT) and digital quasi-peak, peak and average detector algorithms together with the measured corona current. The virtual EMI receiver model algorithm is verified by comparing with measurement results of conducted interference of the three regular waveforms. The influences of computational accuracy on the conducted interference are discussed. Through utilising the laboratory-scale corona cage to generate corona current, the 0.5 MHz excitation current is calculated by using short-time FFT and excitation function theory. The measured and computational average value, root mean square value, quasi-peak value and peak value of EMI receiver response to corona current sequence are obtained. It is found that computations of radio interference have a good agreement with the measured results.

Novel Hybrid Analytical/Numerical Conducted EMI Model of a Flyback Converter

A hybrid analytical/numerical conducted an electromagnetic interference (EMI) modeling approach, which adopts both numerical method and analytical method, is proposed in this paper. In this model, the noise source is calculated directly with the original data from oscilloscopes. The noise path at different operating status is extracted from the original converter topology and its analytical expression is then derived. Also, according to the EMI receiver detector mode, the algorithm of the EMI receiver is proposed in this paper. Peak (PK), average (AV), and quasipeak (QP) values of the EMI can then be calculated to analyze the impact of each relevant component. The analytical method is provided to carry out PK, AV, and QP simulations accurately and fast. The simulation and experimental results for common mode leakage currents validate this EMI model. Furthermore, two analysis examples are given to illustrate how this model is applied for engineers.

Interference Emission Estimation of Domestic Induction Cookers Based on Finite-Element Simulation

In this paper, the interference emission levels of domestic induction heating appliances, which are tested out by the triple-loop antenna proposed by Van Veen and Vergerboet, are analyzed to estimate the measured values from numerical simulations. The purpose of this study is to propose an alternative method to evaluate the emission level of consumer goods in the early stages of the development procedure, prior to perform measurement in a prototype. The constitutive parts of the system have been separately analyzed and modeled, including the equipment under test. Three different blocks have been considered: the inductor heating system, the magnetic coupling between the electromagnetic fields of the system and the output levels of sensor antennas, and, finally, the processing performed by the electromagnetic interference receiver. The description given in this paper provides interference levels at frequencies ranging from the operational switching frequency of the apparatus, typically few tens of kilohertz, to about 1 MHz. Finally, the proposed analysis is verified by comparison of the numerical estimated emission levels and test measurements.

Full-Spectrum APD Measurement of Transient Interferences in Time Domain

Radiated transient interferences produce severe errors to digital communication systems. Conventional measurements defined in the electromagnetic compatibility (EMC) standards are not sufficient to predict the impact of this impulsive noise on the quality of a digital system, as measurements were originally defined to protect analogue communication systems. Measurement detectors and methods based on reaching the statistical of the interference have been studied as the best option to evaluate transient interferences. For a properly EMC emissions evaluation, an amplitude probability detector (APD) has been recommended as the best option, since APD results have been correlated with bit error probability. However, carrying out APD measurements using electromagnetic interference (EMI) receivers has strong inconvenience. One of the main limitations is that measurement can only be performed with the preset filters available at the EMI receiver, which sometimes are different from the communication bandwidths causing an incorrect estimation on the degradation produced. Another restriction is the elapsed time needed to acquire the statistical APD measurement at each frequency band. This document presents a methodology to obtain the APD measurement at any frequency band employing two single time-domain oscilloscope captures. The developed measurement method makes it possible to obtain the APD at any frequency band achieving as good results as the ones acquired from EMI receivers. To show the effectiveness of the time-domain method, an exhaustive validation study is presented, in which white Gaussian noise and several impulsive interferences are evaluated at frequencies from 50 MHz up to 1 GHz.

Electromagnetic Signature Study of a Power Converter Connected to an Electric Motor Drive

This paper investigates the stray magnetic and electric fields of a multifunctional power converter operation while connected to a system involving an induction motor. The impacts of the switching techniques on the radiated fields of the converter were studied for the purpose of electromagnetic interference (EMI) evaluation and fault detection. This was achieved through the inspection of the magnetic and electric fields. Two of the most commonly used switching techniques were implemented through a hardware-in-the-loop system studied in terms of the stray. Various fault and failure conditions were applied to the converter to monitor the converter condition through the stray field observations. A coil and a rod antenna were connected to an EMI receiver to capture the fields. The fields were employed in further analyses. The harmonics and interharmonics of the stray fields were studied in detail for system monitoring purposes. The importance of this paper is to enable the evaluation of the optimum switching pattern for lower EMI field levels from the converter and for condition monitoring and fault diagnosis purposes.

Input Differential-Mode EMI of CRM Boost PFC Converter

In this paper, the differential-mode (DM) electromagnetic interference (EMI) noise of a single-phase boost power factor correction converter operating in critical current mode was analyzed. The DM noise spectra are calculated based on the mathematical model of EMI receiver and the required corner frequencies of DM filter are obtained. It can be seen that the minimum corner frequencies are determined by the maximum noises at 150 kHz. With the relation between the magnitude of the inductor current ripple and the DM noise, the characteristics of noise at 150 kHz are obtained by analyzing the current ripple magnitude at 150 kHz; thus, the worst conditions which have the maximum noise value are figured out. Meanwhile, the maximum noises at 150 kHz for different input voltages are identical, so the DM filter can be designed based on one worst spectrum at one input voltage without testing the spectra in other conditions.

Reducing electromagnetic interferences in flyback AC-DC converters based on the frequency modulation technique

One of the most preferable types of switched-mode power supplies (SMPS) is the flyback converter, due to its wide range of application areas. Properties such as low cost, provision of multiple output voltage terminals, and higher efficiencies make it important, and hence its usage in technologies including cell phone chargers, personal computers, set-top boxes, and televisions is increasing. Special attention should be paid to the design of this type of converter due to its working principles and electromagnetic interference (EMI) performance. Rapid switching of high current and high voltage during the operation of SMPS causes an EMI problem. The level of the EMI noise should be reduced in order to not interfere with the operation of other equipment. One of the methods for mitigating EMI emissions is the frequency modulation (FM) technique. In this paper, the FM technique, which has been increasingly used as an EMI-reduction method in SMPS, is investigated. The modulation technique that was applied to the switching frequency of the flyback converter is analyzed and its effect on the EMI performance is discussed. The FM technique was tested on an AC-DC flyback converter prototype that was built with an L6566B integrated circuit. Conducted emission noises from the SMPS were measured using an EMI receiver. Experimental results showed that EMI levels were reduced after the application of the FM method.

Application of Ant Colony Algorithm to the Analysis of Common Mode EMI Model of DC Motor

The Electromagnetic Compatibility (EMC) of direct current (DC) motor windings is a system model which is used to reflect the functional characters of the system in the whole EMC specified frequency (150 KHz ~ 30 MHz). For most motor designing process, it is always used to evaluate the inductance of windings in lower or working frequency; however, when analyzing the conducted interference, it is necessary to take some pa-rameters in high frequency into account in building up the EMC model, such as the noticeable capacitance distributed among the windings or between windings and shells. Past research neglected the common-mode current generated by the high frequency interference within motor bearings coupled with shells, since the parasitic capacitance of rotor core comes from armature windings supplied sufficient paths. In EMC model-ing process for DC motor problem, first, test the impedance of windings by experiments; then, generate the equivalent circuit with overall parameters. At present, it is a difficulty that how to choose the parameters. Most researchers preferred to adopt analytical calculation results, however, it could not reflect the essence of the model since it requires many simplification. Based on this point, this paper adopted ant colony algorithm (ACA) with positive feedback to intelligently search and globally optimize the parameters of equivalent cir-cuit. Simulation result showed that the impedance of equivalent circuit calculated by this algorithm was the same as experimental result in the whole EMC frequency. In order to further confirm the validity of ACA, PSPICE circuit simulation was implemented to simulate the spectrum of common mode Electromagnetic Interference (EMI) of equivalent circuit. The simulation result accords well with the experiment result re-ceived by EMI receiver. So it sufficiently demonstrated correctness of ACA in the analysis of high frequency equivalent circuit.

A Real-Time Time-Domain EMI Measurement System for Full-Compliance Measurements According to CISPR 16-1-1

Time-domain electromagnetic interference (EMI) measurement systems allow measurement time to be reduced by several orders of magnitude. In this paper, a novel real-time operating time-domain EMI measurement system is presented. By the use of several analog-to-digital converters, the dynamic range requested by international electromagnetic compatibility (EMC) standards is achieved. A real-time operating digital signal processing unit is presented. The frequency band that is investigated is subdivided into several subbands. The EMI signal of the complete frequency band is digitized. By a digital down converter, each subband is shifted toward its baseband and low-pass filtered. The low-pass filtered signal is down sampled. The down-sampled signal is processed by a short-time fast Fourier transform. The obtained spectrogram is processed by a parallel implementation of peak, average, and quasi-peak detectors. The dynamic range of the system has been investigated. A comparison of the digital signal processing to the analog signal processing of an EMI receiver is shown. Measurements have been performed in the frequency range 30 MHz to 1 GHz. Such a system can fulfill the international EMC standard CISPR 16-1-1. By the parallel simulation of several thousand EMI receivers, the measurement at several thousand frequency bins can be performed simultaneously. Due to this benefit, the measurement time can be reduced, and further investigations on a device under test can be performed. These investigations are full characterizations, as well as full scans in the final detector mode, which is especially of benefit for highly unstationary emitting devices.

A low-noise multiresolution high-dynamic ultra-broad-band time-domain EMI measurement system

A time-domain electromagnetic interference (EMI) measurement system allows to reduce measurement time by several orders of magnitude in comparison with conventional systems. This will considerably reduce the costs of compliance tests. In this paper, a novel multiresolution time-domain EMI measurement system is presented. The multiresolution time-domain EMI measurement system exhibits several channels with limiters, amplifiers, and analog-to-digital converters. The amplitude range of the signal is subdivided into several intervals. In each interval the analog-to-digital conversion is performed with an amplitude discretization proportional to the width of the amplitude interval. The signal-to-noise ratio of the multiresolution time-domain EMI measurement system compared with a conventional time-domain measurement system for transient signals is enhanced by at least 50 dB. It is shown that the multiresolution time-domain EMI measurement system has a higher overload factor than conventional systems working frequency domain. The noise floor is 5 dB lower than the noise floor of a conventional EMI receiver. The multiresolution time-domain EMI measurement system shows a higher 1-dB compression point than conventional EMI receivers. Measurements were performed in the frequency range from 30 MHz to 1 GHz and compared with results obtained by an EMI receiver.

Reduction in conducted EMI noises of a switching power supply after thermal management design

Owing to the increasing power density of a switching power supply (SPS), the placement of the components for thermal management and electromagnetic interference (EMI) characteristics is more difficult to design at a given form factor. When thermal management is a critical issue for the SPS, then methods for improving EMI noises seem not to be simultaneously successful at this design stage. As a result, the conducted EMI noises will deteriorate due to the placement of components for thermal management. Furthermore, the performance of the designed EMI filter will deteriorate due to severe internal electromagnetic interference, and thus lead to failure in the EMI conducted measurement. To improve this condition, the locations of EMI noise sources, modes of conducted EMI noise, their coupling paths and the characteristics of the electromagnetic field are investigated in detail. Various shielding schemes are proposed to reduce the EMI inside the SPS. Through this, the interference between the EMI sources, coupling paths and receivers can be significantly reduced so that the conducted EMI measurement of the SPS can meet the requirements. Finally, the effectiveness of the shielding schemes will be demonstrated by some experimental results and some EMI reduction methods will be suggested.

A method to optimize the direction and measurement of EMI signals

The detection and measurement of electromagnetic interference (EMI) signals using conventional EMI receivers and spectrum analyzers is discussed. A statistical approach is used to demonstrate that the probability of detecting a single signal increases as the receiver sweep rate increases. This is then demonstrated in the more general case of multiple signals. Signal density is defined by the Poisson random variable, and an equation is derived that relates the probability of detection to signal density and receiver sweep rate. Also discussed is the choice of types of receivers and detectors that will ensure a maximum probability of detection. A sequential process that first detects signals with a high degree of probability and then performs an accurate measurement of their amplitude and frequency is described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>