Electromagnetic Interference Generation Research Articles

Cyber–physical system for fast prototyping of power electronic converters in EMI shaping context

Dynamic development of power systems, which utilize power electronic converters as interfaces between the renewable energy sources, as well as complex control and measuring arrangements, forces the cooperation of specialists representing various fields to assure electromagnetic compatibility (EMC) of the so-called smart industrial systems. Low voltage DC grid applications involving multiple power electronics devices may turn the grid susceptible to noise injection and impair the signal integrity and power quality due to the electromagnetic interference (EMI) emission and due to devices and grid interactions. The EMI propagation leads to misreading measurements and faulty conditions of equipments and in ICT (Information and Communications Technology) systems within the conducted emission frequency range, which impacts the hosting capacity of the grid. This paper proposes a cyber–physical system based on the NI-PXI platform for fast-prototyping and EMC assessment as pre-compliance tool of low-voltage DC grid in smart industrial systems. Thus, the LabVIEW-based design as well as the EMC-testbench system validation were performed with a DC/DC converter through the pulse-width modulation control algorithms. In addition, a case study has been investigated to evaluate the interferences between the converter and Power Line Communication. Hence, the theoretical control algorithms, hardware and software details, and experimental results are discussed, highlighting the paradigms of one flexible and collaborative cyber–physical system from the area of smart industrial systems.

A Review of EMI Research in Modular Multilevel Converter for HVDC Applications

The modular multilevel converter (MMC) is one of the most critical implementation forms of high voltage direct current transmission. However, the electromagnetic interference (EMI) problems in MMC are unavoidable and complex due to the nonlinear switching behavior of a considerable number of submodules. In this article, the state of the art of EMI research in MMC is reviewed. The characteristics of MMC EMI sources are studied by analyzing the topology and modulation method of MMC and the dynamic turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> processes of the power electronic devices. The standard evaluation and the modeling methods of MMC EMI emission are reviewed by analyzing the EMI propagation paths. In addition, the EMI reduction methods of MMC at sources and along the propagation paths are summarized. Finally, the MMC EMI research is concluded and the future prospects are presented.

Comparative Study of Conducted Common-Mode EMI in WBG-Enabled DC-Fed Three-Phase Current-Source Inverter

In pulsewidth-modulated (PWM) inverters, common-mode (CM) voltage and associated conducted CM electromagnetic interference (EMI) can cause motor bearing failures, ground leakage current, and audio susceptibility issues. When wide bandgap (WBG) devices are used to construct a voltage-source inverter (VSI), the CM EMI issues become more challenging. The current-source inverter (CSI) is an alternative, which produces more sinusoidal output voltage waveforms, making it a promising topology for reducing CM EMI in power converters. However, there is little systematic and comprehensive analysis of CSI’s CM EMI, especially when using WBG devices. The conducted CM EMI generation mechanisms of dc-fed two-level VSIs and CSIs are compared in this article. The analytical derivation and the circuit analysis are performed to identify the CM EMI generation mechanisms in both inverters, including CM voltage sources and the resulting CM current flowing paths. The effects of WBG devices on the CM EMI of both inverters are discussed. New CM EMI equivalent circuits (EQCs) of both inverters are analytically derived to reduce the computational time of full-circuit CM EMI simulation. Different filtering schemes and inverter topology variations’ impacts on CSI’s CM EMI are evaluated using the derived EQC. An effective CM EMI filter is designed to suppress the CSI’s CM EMI to be lower than EMI standards.

Facile fabrication of flexible and ultrathin self-assembled Ti3C2Tx/bacterial cellulose composite films with multifunctional electromagnetic shielding and photothermal conversion performances

With the rapid development of modern electronics, the next generation of electromagnetic interference (EMI) shielding materials requires ultrathin, lightweight, flexibility and robustness to protect electronic devices from radiation pollution. In this study, the multifunctional Ti3C2Tx/Bacterial Cellulose (Ti3C2Tx/BC) composite films with uniformly lamellar structures have been developed by combining experimental and theoretical works. The microstructures, mechanical properties, EMI shielding and photothermal conversion performances of Ti3C2Tx/BC composite films have been systematically investigated. It is highlighted that the resultant ultrathin and flexible Ti3C2Tx/BC composite film with a Ti3C2Tx content of 50 wt% exhibits satisfactory tensile strength of 109.6 ± 4.5 MPa, excellent electrical conductivity of 5020 S m−1 and EMI SE value of 43.7 dB. More interestingly, the composite film displays stable and fast-response photothermal characteristics, with the photothermal conversion temperature up to 74.5 ℃. This study proposes a versatile strategy to synthesize multifunctional MXene/BC composite films with satisfactory mechanical properties, high performance EMI shielding and photothermal conversion effects, which shows great potential for the protection of electronic devices.

Measurement-Based Nonlinear SPICE-Compatible Photovoltaic Models for Simulating the Effects of Surges and Electromagnetic Interference within Installations

An emerging area of interest within photovoltaic (PV) centred research is the simulation of the propagation of electromagnetic interference (EMI) and surges within PV installations. An overarching constraint in all simulation-based research is the accuracy of the models employed. In general, for PV-focussed simulations, nonlinear models are utilised for direct current (DC) analyses, whilst linearised models are employed for analyses involving surges or conducted electromagnetic interference. For large-signal electromagnetic interference and surges, the following two problems arise: (1) the aforementioned linearisation is only valid for the small-signal case, and (2) as they are constructed using only DC measurements, traditional large-signal PV models are generally only valid for DC conditions. Therefore, neither of these approaches can properly represent real-world PV behaviour under dynamic conditions. To overcome this limitation, this article proposes a more suitable model, compatible with Simulation Program with Integrated Circuit Emphasis (SPICE), and which results from the combination of two sub-models: one for large-signal DC cases, and one for small-signal alternating current (AC) cases. Consequently, the combined model enables improved modelling of the effects of large-signal transient perturbations to be performed, as well as cases involving small-signal AC and large-signal DC perturbations. The model parameters are extracted using data from two different classes of measurement setups: the first utilised a vector network analyser (VNA) to produce small-signal AC impedance results (covering a frequency range between 1 Hz and 50 MHz), and the second produces DC current-voltage curves. Both classes of measurement setup consider the device under test at multiple operating points. Key results include: (1) an improved SPICE-compatible PV model which caters for large-signal transient simulations, as well as for small-signal AC and large-signal DC cases, (2) improvements in the modelling of reverse bias behaviour when compared to the standard SPICE diode implementation, (3) the correct implementation of a voltage-dependent total capacitance (suitable for large-signal simulations), (4) modelling parameters for both a small (10 W) and a large (310 W) PV module, (5) measurement results which de-embedded the parasitic effects of the test setups employed, and (6) above 1 MHz, the physical layouts of the cells within the PV modules begin to influence the observed impedances.

Investigation and Reduction of EMI Noise Due to the Reverse Recovery Currents of 50/60 Hz Diode Rectifiers

Alternating current (ac)/ Direct current (dc) power converters with dc-bus filters can achieve high power density, however, it was found in this article that the reverse recovery currents of the 50/60 Hz diode bridge can lead to significant electromagnetic interference (EMI) noise violating EMI standards above 150 kHz. This article analyzed and quantified the mechanism of the EMI generation due to the reverse recovery currents of the 50/60 Hz diodes. It was found that although the reverse recovery of the 50/60 Hz diode bridge repeats at a frequency of 50/60 Hz, the EMI can be very high above 150 kHz due to the operating principle of electromagnetic compatibility spectrum analyzers. Two techniques were proposed to reduce the EMI due to the reverse recovery of the diode bridge. The analyses were validated by either simulations or experiments.

Calculation and Analysis for Spectrum Characteristics Parameters of Switching Device for Reduced EMI Generation

Accurately obtaining the spectrum characteristic parameters of switching devices is very significance for reduced EMI generation on the device switching process. This paper proposed the universal analytical waveform (UAW) to equal the interference source in the device switching process, and analyzed its time and frequency domain characteristic parameters. First, the time domain equivalent method of UAW is proposed, and all the parameters of UAW are calculated with the switching process of the device. Then, the frequency domain characteristic parameters of UAW are mathematically derived based on Fourier transform (FT), and obtained the spectrum envelope functions. Subsequently, the experiments of Si IGBT and SiC MOSFET have been performed to verify the correctness of the UAW, which provides the interference source for electromagnetic interference (EMI) prediction of the system where the device is located. Finally, taking SiC MOSFET as an example, specific solutions to reduce the interference source are discussed, which can be used to diminish the EMI generation of the system where the device located.

Study on the CM EMI Generation Characteristics of the Si/SiC Hybrid Switch at Different Switching Patterns and Gate Resistors

The switching patterns and gate resistor of the Si/SiC hybrid switch are the key to realizing its own highly efficient and reliable operation. However, as an important performance indicator, the common mode (CM) electromagnetic interference (EMI) noise caused by the Si/SiC hybrid switch lacks comprehensive research, which means that it is not clear how the switching patterns and gate resistor affect CM EMI. In this paper, the Si/SiC hybrid switch-based boost converter is established at first. Then, by analyzing the spectral characteristics of the CM voltage of the Si/SiC hybrid switch, the CM EMI generation characteristics of the Si/SiC hybrid switch at different switching patterns and gate resistors are revealed. Furthermore, the analysis and experimental results can be used to comprehensively guide the design of the gate drive pattern, gate resistor, and EMI suppression strategy.

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.

Design of electromagnetic compatibility test platform for transformer fire-fighting nitrogen injection extinguishing system

The transformer fire-fighting nitrogen injection extinguishing system plays an important role in preventing transformer fires in the field of power transformation. However, the fire-fighting system operating on site is often misoperation or non-operation caused by electromagnetic interference and other factors, which affects the reliability of transformer fire extinguishing. This paper builds an electromagnetic compatibility platform for the fire control cabinet of the transformer oil discharge and nitrogen injection system to develop the simulation system of the oil discharge and nitrogen injection fire extinguishing device, and study the factors affecting the reliability of the oil discharge and nitrogen injection fire extinguishing device. Electromagnetic compatibility test refers to a test that uses electromagnetic interference detection equipment and electromagnetic interference generation equipment to assess the electromagnetic compatibility of systems and equipment under laboratory or external environmental conditions. The electromagnetic compatibility test is mainly divided into electrostatic test, electric fast pulse EFT, surge impact and so on.

EMC improvement for high voltage pulse transformers by pareto-optimal design of geometry structure based on parasitic analysis and EMI propagation

High voltage pulse transformers have an essential role in pulsed power systems and power conversion applications. Improving the electromagnetic behavior of such devices leads to better efficiency and low-level electromagnetic interference (EMI) noise propagation in systems. In this paper, a high voltage pulsed power system is considered and analyzed to improve the electromagnetic compatibility (EMC). The new generation of pulsed power systems that use SiC and GaN fast switches in capacitor charger power electronic circuit, face far more EMI challenges. Moreover, in this paper, the EMI propagation paths in the pulsed power system are realized and analyzed. The EMI noise level of the system is obtained and compared to the IEC61800-3 standard. To improve the EMC, the parasitic parameters of the transformer, as the main path of EMI circulation, are optimized to block the EMI propagation in the pulsed power system. For this aim, the parasitics are modeled and calculated with a novel and accurate energy distribution model. Then, by defining a cost function the geometry structure of the transformer is optimized to lower the parasitics in the system. Three pareto-optimal techniques are investigated for the cost function optimization. The models and results are verified by 3D-finite element method (FEM) and experimental results for several given scenarios. FEM and experimental verifications of this model, make the model suitable for any desirable design in any pulsed power systems. Finally, the EMI noise level of the system after optimization is shown and compared to the IEC61800-3 standard.

EMI Noise Reduction for the Single-Phase Grid-Connected Inverter With A Modified Harmonic Filter Design

Harmonics and conducted electromagnetic interference (EMI) are two main issues in grid-connected inverter system. In this article, a modified LCL-LC harmonic filter is structured to strengthen its EMI suppression ability. Considering the common mode and differential mode EMI propagation paths, the traditional LCL-LC filter is split into a symmetrical topology, and with the midpoint of the split filtering capacitors connected to the midpoint of the dc-link capacitor. Compared to the traditional LCL-LC filter, the modified one can maintain the satisfied harmonic attenuation ability and strengthen the EMI suppression. Also, a double closed-loop control strategy is employed to solve the severe resonance problem caused by the harmonic filter. Moreover, a system calibration method is proposed and introduced to design the controller parameters to improve the high-order grid-connected system's stability. A comprehensive analysis and discussions concerning the traditional and modified LCL-LC filters are conducted in simulation and experiment on a 2 kW/220 V/50 Hz single-phase grid-connected inverter. The results have verified the feasibility of the proposed design method, and shown the superiority of the modified LCL-LC filter and active damping strategy in EMI mitigation. Besides, the weight and volume of the harmonic filter can be significantly reduced through this strategy.

A Separate Floating Heatsink Based Suppression Method for Conducted Common-Mode EMI

In order to effectively suppress the intractable high-frequency conducted common-mode (CM) electromagnetic interference (EMI) and reduce the dependence on the high-frequency performance of the EMI filter, this article proposes a separate floating heatsink based suppression method (SFHBSM). SFHBSM suppresses high-frequency CM EMI by improving both the CM EMI source and the propagation path. On the one hand, SFHBSM achieves the nonringing CM EMI source without introducing additional resistive loss, by properly designing the parameters of the SFHBSM, the ringing effect in the CM EMI source can be pushed into a narrow bandwidth in the very high-frequency domain, where the ringing effect can be naturally killed by the skin effect. On the other hand, the CM EMI propagation path of the SFHBSM-based power converter is mathematically deduced, verifying that the SFHBSM can provide effective blocking for the CM EMI propagation in the high-frequency domain. Experiments show that under the combined effect of the ringing suppression and propagation blocking, SFHBSM achieves EMI reduction in almost the whole high-frequency domain, and provides up to 35 dB attenuation in a two-level three-phase power converter. Besides, ablation experiments have been conducted to evaluate the individual and combined effectiveness of each part of the SFHBSM.

A voltage-based detection method for lightning discharges at distribution networks

Overhead distribution networks, due to its exposed nature, are susceptible to the incidence of Lightning Discharges (LD), especially in rural areas. One way commonly employed by power utilities to detect this phenomenon is by using lightning detection systems based on electromagnetic interference propagation. However, these systems do not normally allow for an accurate conclusion if a lightning strike has occurred in a particular feeder. Therefore this paper presents a methodology for detecting such disturbances by measuring voltages at the substation. The scheme is based on a combination of Park and Wavelet transforms applied to these signals. The paper presents a detailed modeling of the IEEE 34 bus test feeder specific for lightning discharges studies. The results show that with the signature of the LD within the measured signals it is possible to detect the transients associated with. This information can be used as a complement of the traditional meteorological based detection systems.

High side flyback circuit configuration for CM noise cancellation

Flyback topologies have advantages in terms of low cost, fewer electrical components, and simple circuit design. Semiconductor devices in the primary and secondary sides are regarded as major EMI noise sources in EMI propagation paths. However, the same transformers under different circuit configurations can bring different noise cancellation effects due to a change of the electric potential distribution in transformer windings as well as the phases of the EMI noise sources in the primary and secondary sides. In this paper, a CM noise cancellation mechanism is investigated. In addition, a flyback topology with high side gate driving in the primary side is proposed to form a CM noise cancellation mechanism. Based on the proposed flyback topology, the capacitor compensation cancellation technique can be applied to lower the electromagnetic interference (EMI) noise level of the designed converter. Finally, the experimental noise spectrums are used to verify the effectiveness of the proposed flyback circuit configuration scheme.

Analytical Model to Study Hard Turn-off Switching Dynamics of SiC mosfet and Schottky Diode Pair

Fast switching transient of SiC mosfet may lead to prolonged oscillations, spurious turn on, large device stress, and high amount of electromagnetic interference generation. For an optimal layout and gate driver design, study of switching dynamics is important. This article presents an analytical model that captures the turn-off switching dynamics of SiC mosfet and SiC Schottky barrier diode (SBD) pair using parameters obtained from device and gate driver datasheets and the values of external circuit parasitics. Unlike linear approximation, a detailed model of channel current is considered that captures the gradual transition from ohmic to saturation region and the transverse electric field effect. A comprehensive model of the transfer capacitance is used and the effect of external gate-drain capacitance is considered. This results in a better estimation of switching transition time, actual loss incurred, (dv/dt), (di/dt), and transient overvoltage. The behavioral simulation and experimental results confirm the accuracy of the presented analytical model over a range of operating conditions for two 1.2-kV discrete SiC mosfet and SBD pairs of different current ratings.

A new analytical conducted EMI prediction method for SiC motor drive systems

Abstract Although silicon carbide (SiC) devices can greatly improve the energy efficiency of electric motor drive systems and increase the power density of inverters as well in electric vehicle applications, fast switching and high-frequency operations of the devices bring more serious electromagnetic compatibility (EMC) problems. It is very important to predict the electromagnetic interference (EMI) level of SiC motor drive systems at design phase. However, since the megahertz resonances caused by the system parasitic parameters can’t be ignored, conventional EMI prediction methods need to be improved. In this paper, the fast switching transient of SiC devices, the power module parasitic parameters, and other detailed circuit parameters are modeled into the EMI sources and propagation paths. In the differential mode (DM) and common mode (CM) EMI sources modeling, both the equivalent switching current sources and the equivalent switching voltage sources of SiC devices are simultaneously taken into account. The proposed analytical method can accurately predict conducted EMI in the SiC motor drive system in frequency range from 150 kHz to 30 MHz. Compared with the previous conventional methods, the proposed method improves DM EMI prediction accuracy of the SiC motor drive system in high frequency range.

A Survey of EMI Research in Power Electronics Systems With Wide-Bandgap Semiconductor Devices

Wide-bandgap (WBG) power semiconductor devices have become increasingly popular due to their superior characteristics compared to their Si counterparts. However, their fast switching speed and the ability to operate at high frequencies brought new challenges, among which the electromagnetic interference (EMI) is one of the major concerns. Many works investigated the structures of WBG power devices and their switching performance. In some cases, the conductive or radiated EMI was measured. However, the EMI-related topics, including their influence on noise sources, noise propagation paths, EMI reduction techniques, and EMC reliability issues, have not yet been systematically summarized for WBG devices. In this article, the literature on EMI research in power electronics systems with WBG devices is reviewed. Characteristics of WBG devices as EMI noise sources are reviewed. EMI propagation paths, near-field coupling, and radiated EMI are surveyed. EMI reduction techniques are categorized and reviewed. Specifically, the EMI-related reliability issues are discussed, and solutions and guidelines are presented.

EMI mitigation in switching power converters combining closed‐loop gate drive and chaotic frequency modulation technique

All switching power converters are characterised by inevitable switching actions with relevant interference emissions. The voltage and current transients of power metal oxide semiconductor field effect transistor (MOSFET)/insulated-gate bipolar transistor are the main sources in switching power converters for both conducted and radiated emissions. In this study, a promising electromagnetic interference (EMI) mitigation method combining the closed-loop gate drive method and the chaotic switching frequency modulation technique is demonstrated for switching power converters. A chaotic pulse-width modulation waveform with Gaussian S-shape switching transients was proposed to achieve remarkable reduced EMI generation at all frequencies. Spectral characteristics of this new switching waveform were investigated by the power spectral density to verify the feasibility of reduced EMI generation. A closed-loop gate controller was presented to shape the switching transients of power MOSFET into the proposed switching waveform. Circuit tests were carried out in both simulations and experiments. The results validated that the proposed method could achieve remarkable EMI mitigation in switching power converters.

Three-Terminal Common-Mode EMI Model for EMI Generation, Propagation, and Mitigation in a Full-SiC Three-Phase UPS Module

With superior loss characteristics, wide bandgap devices such as silicon carbide (SiC) mosfet s are expected to replace Si-IGBTs in grid-connected applications. Uninterruptible power supply (UPS) is an application in which low conduction-loss and switching-loss from SiC devices can largely improve the system efficiency. However, fast switching of an SiC mosfet worsens the electromagnetic interference (EMI). In addition, the UPS is comprised of multiple converters wherein different combinations of the converters take part in power-transfer depending on the mode of operation. This complicates the prediction and strategies for noise, especially the common-mode (CM) part. Such complexity calls for deliberate strategies to be set before prototyping to contain and mitigate the CM noise. In this paper, a three-terminal CM circuit model is presented for a three-phase UPS with an active battery charger and a battery rack. The significance of a dc–dc converter on CM EMI generation and propagation has been analyzed based on the model. In a mode of operation where the dc–dc converter is active, a considerable amount of the CM noise is generated from the dc–dc converter. Also, the multiple resonances on the propagation path associated with dc inductors and the battery rack highly deteriorates CM EMI. As a mitigation strategy in the design phase, different topologies and pulsewidth modulation schemes for the ac–ac stage and the dc–dc stage have been compared based on the model. A 20-kW full-SiC UPS has been built and tested to experimentally verify the impact of the dc–dc converter operation on the noise and to validate the mitigation strategy.