Electromagnetic Interference Emission Research Articles

Strategic electromagnetic interferences suppression in boost converters: zero-switch techniques

This article delves into the growing demand for efficient power conversion technologies accompanying the rise in electric vehicle (EV) adoption. Boost converters, essential for increasing the battery pack voltage to propel EV motors, pose a challenge due to the electromagnetic interference (EMI) generated by the high switching frequency of power devices. To address this issue, practitioners employ zero-voltage switching (ZVS) and zero-current switching (ZCS) techniques. In this comparative study, we systematically evaluate the effectiveness of these soft switching techniques in reducing conducted EMI in boost converters designed for EV applications. The results illuminate the potential of both ZVS and ZCS in significantly mitigating EMI emissions when compared to conventional hard-switching methods. Notably, ZVS soft switching emerges as more efficient and effective, particularly under higher loads, while ZCS soft switching excels in reducing EMI at lighter loads. In conclusion, the study asserts that ZVS soft switching presents a more promising solution for curtailing conducted EMI in boost converters for EV applications, particularly in high-load scenarios. However, it underscores the importance of considering specific operational conditions when deciding between the two techniques.

Investigation into active‐gate‐driving performance and potential closed‐loop controller implementations for silicon carbide MOSFET modules

Investigation into active‐gate‐driving performance and potential closed‐loop controller implementations for silicon carbide MOSFET modules

A novel programmed hybrid modulation for electromagnetic interference mitigation and current ripple control in miniaturised synchronous machine drives

AbstractA novel programmed hybrid spreading spectrum modulation method to mitigate electromagnetic interference (EMI) emission and bearing current in the context of miniaturised and lightweight synchronous machine drives is proposed. The proposed method adopts the combination of conventional pulsewidth modulation (PWM) and low common mode voltage PWM. The offline look‐up table for switching frequency is acquired by analysing the root mean square voltage values at different modulation indices and angles. By adjusting the switching frequency according to this table, the spectrum can be spread into the sidebands of the switching frequency, and the harmonic spike can be suppressed. To address the challenge of increased current ripple and harmonic distortion in high torque density motors under overload conditions, a motor model that considers the cross‐saturation and slotting effect is presented. This motor model is used to derive the switching frequency correction factors, aiming to mitigate the influence of saturation and slotting effect on harmonic amplification. The proposed method is well‐suited for controlling synchronous motors using three‐phase two‐level voltage source inverters. The simulation and experimental results validate the effectiveness of the proposed method, showcasing its advantages in terms of computational complexity reduction and significant attenuation of peak EMI currents.

EMI and IEMI Impacts on the Radio Communication Network of Electrified Railway Systems: A Critical Review

The electrified railway system has been rapidly rolled out in many countries and regions in the past decades, along with the transportation decarbonization agenda. The latest development in power electronics and electrical railway systems has increased the risks of electromagnetic interference (EMI) and intentional EMI (IEMI) emissions, introducing new challenges to the railway radio communications network. It is vital to have a robust and reliable railway communication network that can be resistant and immune to these interferences for the safe and efficient operation of modern railway systems. Yet, the source and new features of EMI and IEMI emerging along with the latest technological development have not been thoroughly investigated and understood. This review paper aims to fill the research gap. First, railway communications systems are introduced. The EMI and IEMI are discussed at the whole system level, and the corresponding impacts on the signaling and communication systems are reviewed comprehensively. Current electromagnetic compatibility (EMC) methods are surveyed, and challenges of tackling the impacts of EMI and IEMI on the signaling and communication systems are discussed. Finally, future research directions are outlined.

Dual randomized discontinuous pulse width modulation for three-phase inverter

ABSTRACT The discontinuous PWM technique, with its advantage over the continuous PWM technique in reducing switching losses in power converters, is gaining popularity. However, its deterministic nature results in discrete harmonics with significant amplitudes, which leads to electromagnetic interference (EMI) emissions. The randomised PWM technique is gaining more interest because of its effectiveness in spreading the harmonic spectrum and thus reducing EMI problems in power converters. This paper presents a carrier-based dual randomised discontinuous PWM (DRDPWM) method for a three-phase voltage inverter. The DRDPWM method combines the random carrier frequency (RCF-DPWM) and random pulse position (RPP-DPWM) schemes. In addition to reducing switching losses, DRDPWM can achieve a broad spread of the voltage spectrum with significantly smaller amplitudes. Furthermore, it produces less inverter output current distortion when compared to traditional DPWM and simple random (RCF-DPWM and RPP-DPWM) schemes. Simulations and experimental results confirm the effectiveness of the suggested method for spreading the voltage spectrum compared to simple random schemes. Additionally, an evaluation of the performance of all randomised discontinuous schemes is conducted based on a number of assessment metrics, including the switching loss factor (SLF), the power spectral density (PSD), the harmonic spread factor (HSF), and the quality factor (QF).

Current Sensor Integration Issues with Wide-Bandgap Power Converters.

Precise current sensing is essential for several power electronics' protection, control, and reliability mechanisms. Even so, WBG power converters will likely struggle to develop a single current-sensing scheme to measure various types of currents due to the limited space and size of these devices, the required high sensing speed, and the high electromagnetic interference (EMI) emissions they cause. Analysis of existing current sensors was conducted in such terms with the objective of understanding the challenges associated with their integration into WBG power converters. Since each of these requirements has different design tradeoffs, it is challenging to consider one specific method of current sensing to be perfect for all situations; thus, the possibility of developing novel methods to improve the performance of these single-scheme current sensors is further explored.

A survey of conductive and radiated EMI reduction techniques in power electronics converters across wide‐bandgap devices

AbstractNowadays, wide‐bandgap (WBG) devices, primarily made from silicon carbide (SiC) and gallium nitride (GaN), are widely applied in power generation, transmission, and conversion. Moreover, the application of WBG devices has had a transformative impact in the field of energy conversion. Compared with Si counterparts, SiC and GaN can remarkably improve the power conversion system efficiency and power density while generating higher electromagnetic interference (EMI) emissions. There are many studies on WBG devices and their behaviour in power systems. However, methods of mitigating EMI/electromagnetic compatibility (EMC) still lack scientific guidance. This article reviews the characteristics of WBG devices, and the significant EMI problems are discussed. Then, the EMI types, EMI causes, and methods of EMI reduction are summarized, and the advantages and disadvantages of these methods are presented as well. Based on the reviewed studies, future research, and the conclusions of this article on EMI/EMC are discussed to help relevant researchers deepen their understanding of the new challenges of EMI brought by the applications of WBG devices, which are useful in engineering.

A Boost Converter with Lossless Passive Snubber for Powering the 5G Small Cell Station

The existing DC-DC quarter-brick or eighth-brick converter with a rated power of 300W is usually designed with a narrow input voltage range from 36 to 72 V DC with limited hold-up time. In this paper, a two-stage power supply unit constructed by a front-end boost converter cascaded with a brick converter is adopted to extend the input voltage range and the hold-up time. A new lossless snubber is proposed and applied to the boost converter to slow the slope of the drain-source voltage rising when the MOSFET is turned off. The experimental results show that the proposed snubber provides a boost converter with a higher conversion efficiency and less electromagnetic interference emissions.

Characterization and Mitigation of Conducted Emissions in a SiC Based Three-Level T-Type Motor Drive for Aircraft Propulsion

This paper presents the full-scale high power inverter design considerations that are needed for minimum conducted noise propagation throughout the system. Specifically, system design issues pertaining to high current and high altitude, high switching transients during commutation process, ribbon cables for high-speed signal transmission, strict conducted emissions requirements and motor side bearing/leakage currents are discussed. Based on the underlying deficits for high power motor drives, layout and circuit design methodologies are proposed to tackle such problems, while keeping costs at a bare minimum. Subsequently, modeling and prediction of common-mode (CM) and differential-mode (DM) noise is made possible using accurate lumped inverter and filter models, allowing for a better understanding of the sensitive components contributing to peak CM-DM noise. A high power (211 kW) rated three level T-type inverter prototype is used to demonstrate the viability of the proposed design techniques for reliable system operation and conducted electromagnetic interference (EMI) emissions mitigation.

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.

Resonant Frequency Deviation Analysis and Modified Notch Filter-Based Active Damping for SiC-Based PMSM Drive With Sine Wave Filter

In the permanent-magnet synchronous machine (PMSM) drive system, the adoption of silicon carbide (SiC) devices brings up new challenges, such as overvoltage, electromagnetic interference emission, and bearing current. To surmount these barriers, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter designed as the sine wave filter can be introduced into the machine drive system. However, filter and stator inductance can create unwanted electrical resonance issues. For the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -equipped PMSM drive system, there are two main factors that cause the drift of resonant frequency and change of stable region: (1) synchronous coordinate transformation with variable fundamental frequency, (2) parameter variations due to the magnetic saturation effect. In this paper, the deviation of resonant frequency caused by coordinate transformation is discussed. Then, the inherent damping effects and stability range in the rotating reference frame are derived in detail. Furthermore, considering the parameter mismatch disturbances, an active damping method based on the enhanced notch filter is presented, of which notch frequency is designed lag behind the nominal resonant frequency. The accurate discretization method and theoretical stability analysis in discrete <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> -domain are conducted. The experimental results are presented to verify the effectiveness and robustness of the proposed analysis and method.

EMI-Regulated SiC-Based Motor Drives With Markov Chain Pseudo-Random Frequency Space Vector Pulse Width Modulation Strategy

Compared with traditional silicon-based (Si) power devices, wide-bandgap (WBG) power devices have broader application prospects in AC motor drive due to their high-temperature reliability, low conduction, and switching losses. However, a fast switching process and high switching frequency will cause more serious conducted electromagnetic interference (EMI) emission. To solve the problem, this paper proposed a pseudo-random frequency space vector pulse width modulation (PRF-SVPWM) strategy based on a carrier with a pseudo-random frequency. There are two sawtooth waves with the same frequency but opposite phases as alternatives. The proposed method randomly selects only one sawtooth wave during a complete control period. After random combination, the generated carrier is no longer a regular sawtooth wave. This new carrier contains 4 different modes including 2 sawtooth (positive and negative) and 2 triangular waves (positive and negative). A 2-state Markov chain is introduced to produce a PRF control signal which is regarded as the law of choice. In this way, the equivalent switching frequency keeps constant but the real-time switching frequency will randomly vary within the determined range. EMI emission level can be significantly reduced. The effectiveness of the proposed PRF-SVPWM is verified by several sets of experiment results.

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.

Spread Spectrum Technique With Random-Linear Modulation for EMI Mitigation and Audible Noise Elimination in IH Appliances

In this letter, a random-linear modulated spread spectrum technique for the induction heating (IH) appliances is proposed. The proposed method can effectively mitigate electromagnetic interference (EMI) emissions and can eliminate audible noises. Besides, it can suppress the total harmonic distortion (THD) compared with other modulations. The proposed random-linear modulation is evaluated by using a 1.8-kW IH prototype system. Experimental results verify the performance of EMI mitigation, audible noise elimination, and low THD using the proposed random-linear modulation compared with those of the conventional periodic and random modulations.

Electromagnetic interference shielding performance calculate model for double layer shielded cable connector in EV

Due to the high voltage and high current working characteristics of EV driving system, strong electromagnetic interference is formed in the working process, and the shielding effectiveness of the high-voltage connector assembly connecting each part of the driving system is directly related to the level of its electromagnetic interference emission. The high-voltage connector is usually made by triaxial method. However, due to the influence of sample coupling length and cutoff frequency, the triaxial method is prone to produce a region of more than 25 MHz, resulting in test failure. Therefore, modeling analysis of the shielding effectiveness of the connector assembly in the early stage is crucial for the final development of a connector assembly with good shielding effectiveness. In this paper, an analytical optimization model named ZTD-Demoulin is proposed to calculate the transfer impedance value of the dynamic shielded wire (double-layer shielded) of the electric vehicle. The model takes into account the influence of the double-layer shielded cable (braided-belt and aluminum foil) on the DC resistance and small-hole inductance of the shielding layer, and analyzes the transfer impedance value which presents the shielding effectiveness of the connector assembly. Based on the double-layer shield optimization model, an optimization model of high-voltage connector assembly is established. This established model takes into account the influence of connector contact resistance and inductance value. Comparison between the triaxial coaxial method and the established model found that when Kconnector = 6Kcable, the fitting effect of the model was the best and the transfer impedance value above 25 MHz could be predicted.

A Flyback Converter With Novel Active Dissipative Snubber

The active clamp flyback converters (ACF) can provide features of high power density and high power efficiency. However, ACF is usually applied to in the applications of medium-to-high power range. For a low power application, the ACF may not be a cost-efficient choice. The flyback converter with a lossless snubber can provide high efficiency for low-power application, but it needs an additional inductor and generates more electromagnetic interference (EMI) emissions. The circuit designers also consider the balance between conversion efficiency, size, and cost. Based on the reasons above, the flyback converter with dissipative RCD snubber is still popular in the applications of low-to-medium power range. When the dissipative snubber is adopted to reduce EMI in the power converters, it increases the loss and hence reduces the efficiency. In this paper, a new concept, called active dissipative snubber, is proposed to suppress the resonance in the discontinuous conduction mode (DCM). In the proposed active dissipative snubber, the digital controller activates the dissipative snubber only when the EMI noise is occurring, then disabled after the noise is decayed or disappears. Digital logic makes the passive snubber smart, which can selectively absorb the EMI noise. Since the proposed snubber is not connected to the main circuit all the time, it can provide lower power loss, but still performs better EMI emissions and maintains conversion efficiency.

Space Vector Techniques for a Binary-Cascaded Multilevel Inverter Operating Under Reduced Common-Mode Voltage With Reduced Commutations

This paper presents a novel space vector pulse width modulation (SVPWM) for a three-phase binary cascaded multilevel inverter. The SVPWM could become impractical in multilevel inverters (MLIs) because of its increasing complexity with a larger number of levels. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gh</i> coordinate system can ease the digital implementation, but to generate the inverter's <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">abc</i> states from the nearest three vectors (NTVs), iterative computations are required every sampling instant. This paper proposes further reduction of computations by directly generating the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">abc</i> state with minimum common-mode voltage (CMV) from a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gh</i> vector. Subsequently, only one vector among the NTVs is required for implementing the proposed SVPWM. The reduced CMV profile within the NTVs further permits the reduction of commutations by clamping one phase during a sampling period. The presented technique exhibits full dc bus utilization capability and can be implemented in the binary cascaded MLI (BCMLI) and further applied to any <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> -level MLI. Also, if <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> is considerably large or if switching losses and electromagnetic interference emissions must be minimized, nearest vector modulation with reduced CMV along with line-frequency operation of high-voltage cells can be implemented to reduce the switching losses. Experiment results of a BCMLI is presented to verify the effectiveness of the proposed technique.

Lossless Snubber for GaN-Based Flyback Converter With Common Mode Noise Consideration

The previous lossless snubber for flyback converters, although with a small number of components, simple control and high power conversion efficiency, has no consideration for electromagnetic interference (EMI). This paper proposes a lossless snubber converter with a novel drain voltage rising slew rate control for the main switch of the flyback converter. Compared to traditional topologies, the proposed snubber topology has two advantages: first, only an additional inductor is used. Second, the proposed method can reduce EMI emissions significantly. Finally, a prototype of the proposed snubber is built and verified with two existing similar snubbers.

Input/Output EMI Filter Design for Three-Phase Ultra-High Speed Motor Drive GaN Inverter Stage

Pairing wide-bandgap (WBG) inverters with high-speed motors results in compact and effi cient motor drives, but requires special attention on electromagnetic interference (EMI) aspects. This paper focuses on electromagnetic compatibility (EMC) of high-speed motor drives, supplied by a DC source. In order to protect the nearby equipment from the EMI noise of the WBG inverter, a fi lter that complies with conducted EMI regulations is placed at the inverter DC input-side. However, there is no clear mandate requiring from inverters to comply with conducted EMI regulations at the AC output-side, where only the motor is placed. For this reason, there is no full consensus whether it is necessary to use an output fi lter, and if so, what type of output fi lter would be suitable, i.e., if differential-mode (DM), common-mode (CM) or both DM/CM output fi lter would fi t best. A full sine-wave output fi lter (FSF) is proposed in this paper, that features both DM and CM attenuation, and capacitors connected to the DC link. Besides the several well established benefi ts of a FSF, such as purely sinusoidal motor currents and the protection of the motor against high du/dt originating from the fast switching of the semiconductor devices, a FSF at the inverter output-side, also reduces the CM EMI emissions at the inverter input-side. Namely, since the inverter housing, the motor housing and the interconnecting shielded cable are all grounded, CM emissions generated at the inverter output-side are directly mapped to the inverter input-side, i.e., there is an input-to-output CM noise interrelation. A FSF reduces the output-side CM EMI emissions and thus mitigates the input-to-output CM noise mutual influence. Two types of FSF (c-FSF and d-FSF) are comparatively evaluated, in terms of volume, losses and EMI performance. The theoretical consideration are tested within the context of a high-speed 280 krpm, 1 kW motor drive, with 80 V DC supply. The experimental results validate the good performance of the proposed filter concept.

Shield Reliability Analysis-Based Transfer Impedance Optimization Model for Double Shielded Cable of Electric Vehicle

Due to the high-voltage and high-current operating characteristics of the electric drive system of electric vehicles, it forms strong electromagnetic interference during the working process. The shielding effectiveness of the high-voltage connection cable that connects the components of the electric drive system is directly related to its electromagnetic interference emissions. Therefore, the modeling and analysis of the shielding effectiveness of the connection cable is very important for the development of a connection cable with good shielding effectiveness. Firstly, the transfer impedance value representing the shielding effectiveness of the shielded cable is analyzed, and the difference between the single-layer shield and the double-layer shield cable is compared. The influence of double-layer shielded high-voltage connection cables commonly used in electric vehicles on the shielding layer DC resistance and keyhole inductance is clarified. Secondly, the transfer impedance optimization model ZT_D-Desmoulins is obtained by combining with the single-layer shielded cable Desmoulins model and considering the influence of shielded layer DC resistance and keyhole inductance. Finally, three double-layer shielded cables of different types were selected for the triaxial test. The error rates of the test data and the ZT_D-Desmoulin optimization model are all lower than 20% in each frequency band, which verified the correctness, universality, and great engineering application value of the optimization model.