Conducted Emission Research Articles

An ultrawideband conducted emission Direct-Coupling Probe calibration method

Conducted emission (CE) measurement is essential to integrated circuit (IC) electromagnetic compatibility (EMC) testing, and accurate calibration of testing equipment is the prerequisite for the reliability of IC CE measurement. This paper proposes an ultrawideband Direct-Coupling Probe (DCP) calibration method. It can effectively improve the deficiencies of the calibration method described in standard IEC 61967-4. Impedance matching calibration fixtures were developed, and a de-embedding algorithm based on time domain reflectometry (TDR) and microwave scattering parameter measurement was proposed. This method can theoretically extend the calibration frequency range of DCP to 20 GHz. The experiment verifies the combination of the algorithm and fixtures can effectively suppress the reflection and ripple caused by the impedance mismatch between the instrument system and DCP and improve the accuracy and repeatability of the measurement process. Factors affecting calibration results, such as fixture characteristic impedance, grounding, and time window selection, are also analyzed and discussed.

Three-Phase Modal Noise Analysis and Optimal Three-Phase Power Line Filter Design

Conducted emissions (CE) for three-phase systems are becoming an increasing concern due to the recent exponential growth of three-phase applications, especially linked to the automotive sector. The problem arises because electromagnetic compatibility (EMC) standards only define the methodology to measure the CE generated by the equipment under test (EUT), and they do not provide sufficient information to design a power line filter (PLF) in case of non-compliance. Hence, the design of an optimal PLF is a very difficult task for engineers. The unclear methodology to be followed, unknown load impedances, inadequate equipment, and lack of knowledge of the modal noise are all different reasons that contribute to increasing the PLF design complexity. Common mode (CM) and differential mode (DM) decomposition and PLF design techniques for single-phase EUTs are well discussed and studied in the literature, but the same cannot be stated when it comes to three-phase PLF design. The objective of this paper is to clarify how modal noises behave in a three-phase system and to propose a clear methodology which can be followed to design an optimal three-phase PLF. Additionally, this paper analyses and discusses the modal noises’ intrinsic behavior and provides an understanding of how the PLF components behave when subjected to either a CM or DM noise. Finally, a methodology to design a three-phase PLF, based on accurate insertion loss (IL) estimations and S-parameter measurements, is used to determine the optimal PLF. This approach is tested and validated.

Passive CM Filter Configuration for a Multistage Grid-Tied Solid State Transformer

<bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">This work proposes a common mode (CM) filter configuration for a grid-tied two-stage AC/DC solid state transformer (SST). The proposed CM filter utilizes passive components along with the heat-sinks of the individual power converter stages to mitigate the overall conducted emissions (CE) injected by the SST system into the grid. The working principle of the proposed CM filter is analyzed and elucidated using CM equivalent circuit models. In addition to CE reduction with the proposed CM filter, it is also demonstrated that the heat-sinks of the SST system can be closer to ground-potential while being impedance grounded. The effectiveness of the proposed CM filter is validated by experimentally measuring the CE of the grid-tied SST system using a Line Impedance Stabilization Network (LISN).</b>

A conducted emission mitigation method for software-defined radios through vector signal cancellation

Recently, Software-Defined Radio (SDR) has gained great popularity owing to its attractive merits, such as flexible signals configuration in multiple channels. However, commercial SDR equipment also has large spurious emissions in the Transmitting (Tx) channel. This paper presents a cascaded model for the Conducted Emission (CE) properties of a general SDR platform, which captures all the key components with high precision. Based on a deeper understanding of the CE properties, a mitigation method is proposed for suppressing the spurious emissions of an SDR Tx channel. This method is based on an efficient vector signal cancellation scheme, in which multiple SDR channels are adopted to suppress the second- and third-order harmonic signals simultaneously. A hardware prototype with dual SDR channels is built and measured for verification. Experimental results show that the suppression level of the third-order harmonic signal is 24 dB on average in the frequency range of 100 MHz to 3000 MHz. The theoretic limit of the suppression level is related to the magnitude and phase errors, and the suppression level may be further improved by calibrating each SDR channel.

PLF Design for DC-DC Converters Based on Accurate IL Estimations

Even though today’s electromagnetic compatibility (EMC) standards and measurement techniques set specific limitations and a clear methodology to measure the conducted emissions (CE) of equipment under tests (EUTs), the design methodology of a suitable power-line filter (PLF) to solve non-compliance is, in general, neither accurate nor efficient. This is due to different reasons, such as unknown actual load and line impedances, unknown dominant mode in the CE, and/or inappropriate instrumentation for the appropriate measurements. The objective of this paper is to investigate if different topologies of switching mode power supplies (SMPSs) lead to different PLF structures. For the sake of exemplification, the analysis is focused on switched-mode DC-DC converters. From an EMC point of view, these devices can be completely modeled by means of Scattering (S)–parameter and CE measurements. Additionally, an analysis of their circuit models has been performed to allow a better comprehension of their characterization. In this paper, the circuit models of three different types of DC-DC converters are presented, and their component values (including nonlinearities and parasitic effects introduced by the actual behavior of the circuit elements) are estimated using the S-parameter characterization. Then, a new methodology for PLF design, based on accurate insertion loss (IL) estimations, is applied to obtain the optimal PLF for one of the converters. This methodology is experimentally tested and validated.

Multiscale EMC Modeling, Simulation, and Validation of a Synchronous Step-Down DC-DC Converter

The proliferation of power electronics in automotive and industrial applications raises compliance challenges in meeting electromagnetic compatibility (EMC) regulatory standards. In this work, we develop a robust multiscale system-level modeling and simulation methodology for predicting CISPR 25 conducted emission (CE) and radiated emission (RE). The method is based on a novel two-stage process. In the first stage, the IC model is generated either by non-linear time-domain simulation using a device-level physics model or oscilloscope measurements if a prototype is available. In the second stage, the IC model waveforms are used in a simulation environment comprising 3D full-wave frequency domain analysis and specially prepared macro-models for the laboratory equipment. Silicon validation of CISPR 25 EMC measurements on a “low-EMI,” high-performance DCDC automotive/industrial synchronous step-down converter is presented to validate the integrity of the predictive modeling methodology. Good correlations between modeling and EMC-certified testing laboratory emission measurements are achieved (i.e., within +/- 3dBuV for CE and +/- 6dBuV for RE). As a result, the predictive EMC modeling methodology can be implemented, early in the design cycle, to ensure first-pass EMC-compliant design.

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.

Simulation of conducted emission voltage method for DCDC converter in electric vehicle

In order to quickly predict the conducted emission (CE) of electric vehicle (EV) DC/DC converter, a co-simulation analysis method based on HFSS-simplorer is introduced. The detailed 3D models of magnetic devices, PCB board and metal structure, and the active device nonlinear models are added to the co-simulation circuit. The method is used to simulate and analysis the EMC performance of the conducted emission of the actual electric vehicle DC/DC converter, the simulation results are in good agreement with the test results in magnitude, trend and peak values, which shows that the method is feasible and practical.

Inter Laboratory Comparison (ILC) of Both Quasi-Peak and Average Mode Measurement Results of Conducted Emission (CE) Test for Better Analysis of Performance Evaluation of EMC Laboratories

This paper presents a comprehensive analysis of Quasi-Peak (QP) and Average (AVG) modes measurement results obtained by Inter Laboratory Comparison (ILC) of Conducted Emission (CE) Test as per CISPR 22. ILC, a mandatory requirement of International Standard ISO/IEC 17025 as part of Quality Assurance is accomplished by utilizing Comparison Noise Emitter (CNE III) source (150 kHz–30 MHz) which is widely used for ILC measurements of EMC Test facility. CE Test results and data with estimated measurement of uncertainty reported from seven NABL (National Accreditation Board for Testing and Calibration Laboratories) accredited EMC Laboratories in India are presented in Quasi-Peak and Average detection modes over the frequency range of interest under controlled environment. The reported emission is in the range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$66.40\ \text{dB}\mu\mathrm{V}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$79.06\ \text{dB}\mu\mathrm{V}$</tex> for QP mode measurement. Whereas, the reported emission is in the range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$62.11\ \text{dB}\mu \mathrm{V}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$72.70\ \text{dB}\mu\mathrm{V}$</tex> for AVG mode measurement. Z-Score is calculated for all seven EMC Laboratories over 0.150 MHz–30 MHz range for both QP and AVG modes measurement results using Robust Method. In case of QP mode measurement, 99% of the result exhibited <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Z-Score}\leq 2$</tex> . Whereas, in case of AVG mode measurement 98% of the result exhibited <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Z-Score}\leq 2$</tex> . Further, there were only two EMC Laboratories found to have outlier values in case of QP measurement. Whereas, there were three EMC Laboratories found to have outlier values in case of AVG mode measurement. Hence, this paper intends to report that Z-Score values shall be calculated for both QP and AVG modes measurement results for better analysis of performance evaluation of EMC Laboratories.

Analysis of the Influence of Measurement Circuit Asymmetries on Three-Phase CM/DM Conducted EMI Separation

Electromagnetic interference (EMI) conducted emissions (CE) are of increasing concern in power electronics due to the high switching frequency and fast switching speeds of the latest generation of wide-bandgap semiconductors. The decomposition of the total conducted EMI noise into its common-mode (CM) and differential-mode (DM) part by means of a CM/DM noise separator is a useful tool that allows for a systematic EMI filter design. Carefully designed realizations achieve a CM rejection ratio and DM rejection ratio of 50 dB at 30 MHz. However, a very high-performance CM/DM noise separator is not sufficient. It is theoretically analyzed and experimentally proven that asymmetries in the EMI test setup result in an unwanted conversion between CM and DM EMI noise, and therefore significantly influence the CM/DM EMI separation. In particular, three main influences are identified: the line impedance stabilization network (LISN), the connection cables between LISN and the equipment under test (EUT), and the converter EMI filter. The unwanted noise conversion is pronounced for frequencies in the MHz range, where parasitic resonances occur. Experimental results show a CM-to-DM conversion of up to -30 dB at 30 MHz (a degradation by 20 dB or a factor of 10 compared to a high-performance separator alone) considering a connection cable length mismatch of roughly 5 cm. Values as high as -21 dB result when standard commercial LISNs are used for the measurement. The impact of asymmetries in the EMI filter is most severe, and clearly limits the EMI noise splitting at high frequencies. A high-performance noise separator can, however, be used to investigate such filter asymmetries (component tolerances and/or layout), and therefore helps to improve the filter design process and facilitates the modeling of EMI noise sources. [COMP: Change bullet list to numbered].

Design and Experimental Analysis of a Three-Phase Active CM/DM Conducted EMI Noise Separator

This work investigates three-phase electromagnetic interference (EMI) conducted emission (CE) measurements with the aim to separate the noise voltages in their common-mode (CM) and differential-mode (DM) parts. By doing so, the converter input and/or output filter stages can be individually optimized to improve the CM or DM attenuation depending on the origin of the CE disturbances. An overview of various ways to achieve this separation is provided and an active three-phase noise separator is presented. The main advantage of the presented active solution is the absence of magnetic components in the signal path which drastically facilitates the matching at high frequencies. The influence of asymmetries and mismatches of the component parasitics as well as in the circuit board layout are analyzed. To assess the performance of the proposed system according to widely known metrics such as CM and DM transfer functions and rejection ratios, different test methods are established and the implied limitations regarding maximum measurable performance are considered. Finally, experimental results verifying the calculated separation capabilities are provided.

Noise Reduction on The Use of Different Ground Model on The EMI Filter of Reading and Desk LED Lighting for Passenger Train

Initial measurement showed that reading LED lighting used in this experiment produced excessive conducted emissions (CE). EMC filter is needed to suppress the CE noise. The LED light is AC powered through a two-wire cable without ground wire, whereas the EMC filter does have ground. Experiments were conducted to find out the attenuation effect of different filter’s grounding connection methods. Four cases of grounding connections are measured and compared, i.e. unconnected ground, earth-connected ground, chassis-connected ground, and additional ground plate. Measurements showed that chassis-connected ground had the strongest attenuation effect. Also, for the additional ground plate configuration, it turned out that larger plates exhibited stronger attenuation compared to smaller plates. Keywords : LED driver, EMC Filter, grounding, impedance, common mode

The Conducted Emission Attenuation of Micro-Inverters for Nanogrid Systems

Road lighting systems require a significant amount of electric energy. To compensate for the utilized energy, the concept of a nanogrid road lighting system is presented. A solar panel is installed on the top of a lighting pole to generate electric power. In this research, a photovoltaic simulator (PV simulator), which is used to simulate solar behavior such as current, voltage, and power based on temperature and solar irradiance levels, is employed to replace a solar panel. In the nanogrid system, grid-connected and stand-alone micro-inverters are employed to convert the electric power. The inverters comprise switching devices that can generate electromagnetic interference (EMI) when operating, which is harmful to the grid system and the electrical equipment. In general, EMI has been studied and reduced in electrical appliances, which only receive electric power. However, for the nanogrid system, which supplies electricity to the grid system, there is less study on the EMI topic because the usage is still not widespread. In the future, the nanogrid system will be widely used delivering high power directly into the electrical grid system. Therefore, the study and attenuation of EMI in the nanogrid system are very promising. Conducted emission (CE) is one form of EMI that flows through a cable connecting several appliances in the frequency range of 150 kHz to 30 MHz. CE of grid-connected and stand-alone micro-inverters have high levels in the low-frequency range between 150 kHz–5 MHz and then decreases steadily. CE attenuation is important for this inverter in a solar power system. This research studies the effect of CE mitigation on the nanogrid system. The result is compared with the Comité International Spécial des Perturbations Radio (CISPR) 14-1 standard. Finally, the passive EMI filter can reduce CE and meets the CISPR 14-1 standard.

A Proposed Terminal-Ground EMI Filter for Reduction of Conducted Emissions Considering Cable Radiation and Safety

This article proposes an optimal design of a terminal-ground electromagnetic interference filter (TGEF) for reduction of common-mode (CM) conducted emissions (CEs) with considering cable radiations and safety. The TGEF is free from risks of magnetic saturation and heat problem. In experimental tests with a 3.3-kW air conditioner system, a prototype TGEF well reduced low-frequency CM CE noises, but increased disturbance power (DP) due to cable radiations. To investigate the principle of cable radiations, the impedance and parameters in the DP measurement setup are extracted by measurements using a vector network analyzer and validated with full-wave simulations. The effects of the TGEF on total CM DP currents at power cables are also experimentally demonstrated and modeled in simulations. Based on the analysis of DP measurement environments, a quantitative guideline for a TGEF design was proposed without increasing cable radiations while maintaining CE noise attenuation performances. The performances of the optimized TGEF are then validated by CE and DP measurements in the real product system. Moreover, safety of the optimized TGEF in a ground-fault condition was experimentally confirmed.

A CM Filter Configuration for Grid-Tied Voltage Source Converters

Common mode (CM) filters play a crucial role in determining adherence to conducted emissions (CE) standards for grid-tied voltage source converters. Design and implementation of such filters can be challenging since they depend on several factors like identification of CM noise paths, fidelity of passive components and discerning the frequency and amplitude of CM noise sources. In this article, a CM filter has been proposed, which uses passive components along with the converter's heat sink as a circulating return path for the CM currents. Based on the presented CM circuit models with the proposed filter, a detailed design process has been delineated for selecting the passive components required to realize the CM filter. Additionally, the heat-sink potential has been shown to be touch safe during both ideal and nonideal grid conditions with the proposed CM filter. CE spectral results measured using a commercially procured line impedance stabilization network and captured time domain converter operational wave forms for a 2-level, 3π grid-tied voltage source converter validate the functionality and effectiveness of the presented design.

Characteristics and Effects of Conducted Emission from Grid-Connected and Stand-Alone Micro-Inverters in a Nano-Grid Road Lighting System

A road lighting system is important for drivers and uses a lot of energy. The road lighting system must be installed throughout roads which have a long distance and a large volume, which causes power loss in the power transmission line. The concept of combining a power generation system by using a solar power system and a road lighting system is presented to solve this problem; it is called “a nano-grid road lighting system”. The nano-grid system consists of a grid-connected system and a stand-alone system and both systems use micro-inverters to convert the electric power for LED luminaire loads. Both micro-inverters are comprised of switching devices that cause the conducted emission (CE) in the electrical system. The LED luminaire is a very sensitive load because it is less resistant to the CE. Therefore, this research studies the CE in the nano-grid system in each period according to the working pattern of the device to study the CE characteristics for use in the design of CE attenuation methods in the future. The CE of the stand-alone system which is used at nighttime gives a higher level than the grid-connected system and exceeds the Comité International Spécial des Perturbations Radioélectriques (CISPR) 14-1 standard. The CE of the grid-connected system has a high level in the early frequency ranges, whereas the CE of the stand-alone system has a high level throughout the test frequency range.

A Transformer-Isolated Common-Mode Active EMI Filter Without Additional Components on Power Lines

This paper proposes a new structure of transformer-isolated active EMI filter (AEF) without additional components on power lines for the reduction of common-mode (CM) conducted emissions (CE). The noise attenuation performance and loop gain are rigorously analyzed, and the design guides for the proposed AEF are developed. The AEF is designed in a compact package for the application to a switching mode power supply. The performance, stability, and leakage currents of the AEF are experimentally validated by various measurements. The CM EMI filter, including the AEF, achieves the additional CE reduction by 10 to 20 dB at a frequency range lower than 1 MHz. Also, the noise peaks due to the resonances at several MHz are reduced by 7 dB. The weak points of the conventional CM EMI filter at both low and high frequencies are effectively improved by employing the proposed AEF.

Conducted EMI Analysis of Vehicle Positioning System and Strategies to Reduce Conducted EMI

The main objective of this research proposal is to measure the Conducted Emission (EMI) and propose mitigation techniques in order to meet the Electromagnetic Compatibility (EMC). For this research work, GPS based Vehicle Positioning System has been taken as a model. The Conducted Emission (CE) test on GPS based system has been performed at the Centre for Electronics Test Engineering, Pune and Automotive Research Association India Pune, India. This model was first tested without Radio Frequency Interference (RFI) filter. The EMC standard is specified for the frequency range of 150 kHz to 108 MHz for Conducted Emission measurement. The RFI Filter is proposed, as a one of the technique to reduce CE level. The CE level has been reduced significantly by using proposed RFI Filter. The results obtained were compared with the CISPR 25, SAE J1113 Automotive standard in order to investigate the effectiveness of the applied EMI filtering mitigation technique. The analysis and experimental results finally shows that the Conducted Emission has been reduced by around 30 dB using the RFI filter, making the system compatible with the EMI/EMC Standard.

Prediction of Conducted Emissions in Satellite Power Buses

This work reports a modeling methodology for the prediction of conducted emissions (CE) in a wide frequency range (up to 100 MHz), which are generated by dc/dc converters and propagate along the power buses of satellites. In particular, the dc/dc converter seen as a source of CE is represented by a behavioral model, whose parameters can be identified by two unit-level experimental procedures performed in controlled test setups. A simplified multiconductor transmission-line (MTL) model is developed to account for the propagation of CE in shielded bundles of twisted-wire pairs used as power cables. The whole power system is represented by the interconnection of the circuit models of dc/dc converters, cables, and Power Conditioning and Distribution Unit (PCDU). By solving the obtained network, frequency spectra of CE can be predicted. Experimental results are reported to substantiate the accuracy of the proposed unit-level dc/dc converter model and the MTL model of cables. Finally, a system-level test setup composed of three dc/dc converters connected to a PCDU is considered, and predicted CE are compared versus experimental measurements.

Design Technique and modification of Power line filter using passive lumped components

A unique design technique of power line filter is being proposed. It is based on the conventional technique of composite low pass filter. The equivalent circuit of the composite low pass filter is being presented in the two different modes by considering the modal propagation of noise. The consideration of composite LPF is taken into account in the design technique of power line filter. In order to accurately predict the insertion loss of the filter the effects of non-ideal behaviour of the passive lumped components are considered. It is based on the parasitic effect of the passive lumped elements. The filter is then characterized using S-parameters. The response of the filter's circuits is simulated using advanced design software (ADS). Keywords: Conducted emission, Composite filter, electromagnetic compatibility, lumped elements, and power line filter. I. Introduction Switching and modulation techniques are used for efficient use of electrical power. Widely used Switched mode power supplies (SMPS) for powering today's electronics loads is a most common example. Unfortunately, all the power control techniques deliberately distort sinusoidal wave form of power frequency and generate unwanted interfering signals. Obviously, they all are often cited as one of the main source of conducted emission (CE). Usually the power supplies which are using controlling techniques cannot comply with the strict electromagnetic compatibility (EMC) regulations. In order to meet the limit set for conducted EMI, power supplies require a filter at its input. Conducted EMI generated through particular equipment gets coupled into other equipments mostly through power line cables. CE can be controlled by using filters and increasing line impedance. Conducted EMI has two components: The common mode (CM) interference and differential mode (DM) interference. The coupling mechanisms of these interferences are different (4). The difference in the direction of propagation of these coupling currents along the phase and neutral line, leads to differential mode ( ) current and common mode ( ) current. Therefore design of EMI filters demand decoupling of these two modes (2). This paper attempts to describe a design technique for Power Line filter using classical design technique. 1.1 Characterization of common mode & differential mode currents