Conducted Electromagnetic Interference Noise Research Articles

Suggesting a Non-Unity Turn Ratio Two-Winding Coupled Inductor for Filtering CM EMI Noise in an SRC

Switched-mode power supplies (SMPS) are the source of both conducted and radiated electromagnetic interference (EMI) noise. Resonant converters are popular due to the possibility of switching loss reduction using zero voltage switching (ZVS) or zero current switching (ZCS) and also attenuating conducted EMI noise. Conventionally, a common-mode (CM) choke with a single core and two identical windings is used to suppress the CM noise in an EMI filter. This paper introduces an effective and cost-efficient method for mitigating the CM EMI noise in SRCs. The proposed method benefits a two-winding coupled inductor instead of the simple resonant inductor in the SRC. While a unity turn ratio does not meet the desired resonance inductance, the suggested two windings coupled inductor with an unequal number of turns deals with the EMI noise as well as the normal operation of an inductor in the resonant tank. Applying the proposed method significantly achieves up to 20 dB attenuation in the noise amplitude both at the input and output terminals of the converter. Simulations are used for investigating the analysis of the method. Moreover, a series resonant converter is designed and implemented to verify both analysis and simulations.

Conducted electromagnetic interference mitigation in super-lift Luo-converter for electric vehicle applications

In this article, a digital chaotic pulse width modulation (DCPWM)-dependent electromagnetic interference (EMI) noise attenuating procedure has been implemented. With the aid of a field programmable gate array (FPGA), a randomized carrier frequency modulation with a fixed duty cycle has been generated through chaotic carrier frequency, and this process is called DCPWM. Conducted EMI suppression is achieved in a 200 kHz, 40 W elementary positive output super lift Luo (EPOSLL) converter using the DCPWM technique. The results are compared and validated with periodic PWM over DCPWM in simulation and hardware with electromagnetic compatibility (EMC) standards. Besides, 9 dBV (2.81 V) of conducted EMI noise has been minimized in the DCPWM approach against periodic pulse width modulation method for the EPOSLL converter in electric vehicles applications.

A comparison statement on DCPWM based conducted EMI noise mitigation process in DC-DC converters for EV

Fast switching techniques at high frequencies are employed for quick charging and energy conversion in electric vehicle (EV) power converters. Electromagnetic interference (EMI) noise is produced due to the fast-switching process, which may result in malfunctioning and degraded EV performance. In this work, a digital chaotic pulse width modulation (DCPWM) technique-based EMI noise mitigation process has been applied to elementary positive output super lift Luo (EPOSLL), two-stage cascaded boost (TSCB), and ultra-lift Luo (ULL) converters, and a comparison study has been conducted with EMI reduction levels as per electromagnetic compatibility (EMC) standards. The duty cycle is varied from 0.5 to 0.67 to get the desired output voltage as an input of 10V to achieve the power ratings of 40 W to 80 W for various load conditions. A total of 4 dBV (3 V) to 15 dBV (10 V) of conducted EMI noise has been mitigated for the above-said converters. Simulation results based on power spectrum density and hardware results based on fast fourier transform (FFT) of output voltages are analyzed. According to the findings, the ULL converter is more acceptable for electromagnetic compatibility in EV applications than EPOSLL and TSCB DC-DC converters.

Analysis of Common-Mode Noise and Mixed-Mode Differential-Mode Noise in Dual Active Bridge Converter

The dual active bridge (DAB) converter is one of the widely explored topologies in recent years due to its remarkable features, such as inherent soft-switching characteristics, galvanic isolation, and high power density. However, the conducted electromagnetic interference (EMI) analysis of the DAB converter is seldom reported. In this article, the common-mode (CM) and the differential-mode (DM) equivalent circuits of the isolated DAB converter are presented to understand the propagation mechanisms of the conducted EMI noise in the converter. In particular, the mixed-mode DM (MMDM) noise component of the DM noise is quantified for the DAB converter. Furthermore, an experimental measurement method based on an external impedance-matched circuit is proposed to quantify the DM current due to capacitive coupling between the primary and secondary windings of the transformer. The quantified MMDM noise and the DM noise through the transformer are estimated using the proposed equivalent circuits in MATLAB-Simulink and validated experimentally on a prototype DAB converter.

High Efficiency Common Mode Coupled Inductor Bridgeless Power Factor Correction Converter With Improved Conducted EMI Noise

The conventional power factor correction (CPFC) converter suffers from excessive heat generation due to high conduction loss from the input bridge diode. Various bridgeless PFCs (BPFCs) have been proposed to overcome this drawback. Among them, the conventional BPFC (CBPFC) features the significantly reduced conduction loss but has very poor conducted electromagnetic interference (EMI) noise. Further, the semi-BPFC features the reduced input diode loss and good EMI, but the input diode loss is too significant to ignore. Although another solution, totem-pole BPFC, features high efficiency and good EMI, it usually requires expensive current sensors and microprocessor. A BPFC with the integrated magnetics common mode coupled inductor (ICC) is proposed to overcome the drawbacks of traditional BPFCs. The ICC can significantly reduce the system size by integrating three inductive components into a single magnetic core. Moreover, the small magnetizing current of the ICC, not the main input current, flows through input diodes; thus, experimental results from a 600 W rated prototype prove that the input diode loss can be significantly reduced by about 10 W compared to the CPFC, and the input diode exhibits a low heat generation of 49.8 °C despite the absence of a heat sink. In particular, with the help of input diodes, the EMI noise spectra of the ICC BPFC can meet the EMI standard with a sufficient margin. The detailed analysis, design guide and experimental results from a 600 W rated prototype are provided to confirm the validity of the ICC BPFC.

Modeling of line impedance stabilization network impedance characteristic based on genetic algorithm

The line impedance stabilization network (LISN) is commonly used to measure the conducted electromagnetic interference (EMI) noise produced by electronic equipment. In order to improve the measurement accuracy of the conducted EMI noise, the characteristics of the LISN should be verified and calibrated, such as impedance and voltage division factor. However, the parasitic parameters of capacitance and inductance are critical to the performance of the LISN. In this paper, the high-frequency model of the LISN is proposed based on the topology and parasitic parameters. The impedance of the LISN is obtained from 150 ​kHz to 30 MHz based on scattering parameters method and vector network analyzer (VNA). The parasitic parameters of capacitance and inductance are extracted by employing the elite genetic algorithm (EGA), LISN topology and impedance. The voltage division factor and impedance of R&S LISN ENV216 is obtained and calculated by employing the proposed method, which verify the proposed method effectiveness. The work will contribute to the further design and calibration of the LISN, and improve the conducted EMI noise measurement accuracy.

Design of a Fully Integrated EMI Filter for a Single-Phase Grid-Connected Inverter

EMI filter is an essential part of the inverter system due to the high operative switching frequency of power switch tube. The optimization of electromagnetic interference (EMI) filter design has a far-reaching impact on the coming industrial application area. Based on the Silicon carbide (SiC) MOSFET single-phase inverter, this article investigates a full integration strategy with the UU-type ferrite core and flexible multi-layer foil (FMLF) applied. The FMLF contains electrical-, dielectric- and insulation layers. With the ingenious design of the FMLF windings, the inductance and capacitance can be integrated into the same unit. Based on the special design with double dielectric layer embedded, a novel full integration structure comes into being, with the common-mode (CM) and differential-mode (DM) capacitance designed following with the CM and DM inductance. The magnetic simulation has been conducted for analyzing the structure and ensuring that the core will not reach saturation under full load. A SiC MOSFET single-phase inverter has been designed as the experiment platform, and the conducted EMI noise measurement results have verified the feasibility and validity of the proposed fully integrated structure.

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.

Study on conducted EMI noise source modelling applied in electromagnetic compatibility analysis based on GA in cooperation with LM

In this study, a new method employing scattering parameters (SPs) method, genetic algorithm (GA) and Levenberg–Marquardt algorithm (LM) is proposed for modelling conducted electromagnetic interference (EMI) noise source impedance. On the basis of the impedance information extracted by traditional SP method, GA is adopted to optimise the impedance information by taking advantage of the fast convergence speed. The obtained values of the RCL parameter are used as a set of initial values. Then, by using the advantage of the high precision of the LM, the initial values obtained by the GA are iteratively calculated. Better results can be obtained by using this combination method. This method improves the processing accuracy while ensuring the processing speed and contributes to the design of conduction EMI filter.

Closed-Loop Gate Drive for Single-Ended Forward Converter to Reduce Conducted EMI

Forward DC/DC converters are widely used in low and medium power circuits that are widely used in the aerospace and navigation fields. Power converters are usually sources of electromagnetic interference (EMI), which is due to their higher voltage and current transients. The traditional method is to add expensive filters on the primary side or the secondary side, but its disadvantages are high cost and poor adjustability. Based on the principle that the greater the number of derivations of voltage transients, the lower the high frequency electromagnetic interference contained in this voltage, a signal containing small high-frequency noise that is suitable for the hardware circuit as a reference signal is selected, and a closed-loop gate drive method is used in this paper, which attenuate the conducted EMI noise in the input bus of the forward DC/DC converter. The reference signal shapes the output signal to achieve the purpose of suppressing electromagnetic interference through the closed loop circuit. The advantages of this method are making the output highly adjustable, reducing hardware size and weight and lower cost compared with filter method. Compared with the method of controlling current to reduce electromagnetic interference, the proposed method is easier to implement. Firstly, the relationship between the derivative order of voltage transient and electromagnetic interference is introduced. Secondly, the experimental principle of single-ended forward circuit controlled by closed loop is introduced. Simulation and experimental results show that the proposed method can achieve voltage shaping and suppression of voltage overshoot effectively. Compared with the traditional hard-switching control method, the proposed method can make the high-frequency components of the drain-source voltage of the primary-side MOS transistor and the secondary-side output voltage have a greater attenuation.

Analysis and Modeling of Conducted EMI from an AC–DC Power Supply in LED TV up to 1 MHz

Critical conduction mode (CRM) boost power factor correction (PFC) converter is widely used in ac–dc power supplies to achieve high power factor. The switching frequency varies in a half-line cycle. In this article, both the differential-mode (DM) and common-mode (CM) electromagnetic interference (EMI) noises below 1 MHz from the ac–dc power supply in a LED TV are analyzed and modeled. The power supply consists of two parts: CRM boost PFC converter and LLC resonant converter. The conducted EMI noise and noise source voltages are measured in the time domain and then converted to the frequency domain via short-time fast Fourier transform (STFFT). Through the joint time-frequency analysis using STFFT, the drain-to-source voltage of the power MOSFET in the PFC converter is identified as the dominant noise source of both CM and DM EMI noises below 1 MHz from the power supply. The EMI current path is different during different periods of a cycle of the line voltage. During most time of a cycle, two diodes of the bridge rectifier are forward biased, and the bridge rectifier can be treated as short circuit. The current paths of DM and CM EMI noises are explained and modeled by a linear equivalent circuit model. Three parasitic capacitances need to be considered to model the CM EMI noise in this device under test. From the circuit model, transfer functions relating DM and CM EMI spectra to noise source voltage spectrum are obtained. The conducted EMI spectra are predicted by multiplying the spectrum of noise source voltage by the transfer functions. The prediction matches with measurement. The effects of parasitic capacitances on CM EMI noise are analyzed by simulation and then validated by measurement. The analysis results can help with EMI design to reduce the CM EMI.

A Survey of Active EMI Filters for Conducted EMI Noise Reduction in Power Electronic Converters

Wide bandgap devices enable high power density power converters. Despite the advantages of increased switching frequency, the passive components are still a major bottleneck toward enabling high power density. Among the passive components in the converter, the passive electromagnetic interference (EMI) filters are unavoidable to ensure compliance with conducted EMI standards. Active EMI filters (AEFs) help reduce the volume of the passive components and have been around for three decades now. The design and implementation of the AEFs depend upon the type of noise (common-mode or differential-mode) and power converter (ac–dc, dc–dc or inverter). This article presents a comprehensive survey of different AEFs and their implementations for different power converters presented in the literature. A comprehensive survey of noise-sensing, noise-processing, and noise-cancellation circuits is presented. Also, a comparison of attenuation provided by the AEFs for common-mode and differential-mode noises for different converters is carried out. Furthermore, other facets of AEFs such as the auxiliary power supply, power loss, and protection methods for the AEF are also summarized. This article is intended to be a useful reference for power converter designers in both industry and academia.

A Simulation-Based Multifunctional Differential Mode and Common Mode Filter Design Method for Universal Converters

Existing filter design methods for grid-tied power converters either focus on grid current harmonic suppression or electromagnetic interference (EMI) noise attenuation. This article proposes a simulation-based, multifunctional filter design method, which can simultaneously handle multiple objectives, including minimizing grid current total harmonic distortion (THD), conductive EMI noise, ground leakage current, touch current, filter weight, and so on. By modeling equivalent filter circuit and simulating in the Powersim (PSIM) software, the approach avoids traditional complicated circuit analysis and mathematical computation. In addition, unlike most existing filter design approaches that only focus on one specific application or converter topology, this filter design method is a generalized approach and can also be used for universal converters that have variable applications. To demonstrate this feature, the filter design method is applied to a recently proposed series-capacitive-link universal converter. Experimental results verify the effectiveness of the proposed method.

Investigation on conducted EMI noise source impedance extraction for electro magnetic compatibility based on SP‐GA algorithm

A new approach employing scattering parameters (SPs) and genetic algorithm (GA) (SP-GA) is proposed for modelling conducted electromagnetic interference (EMI) noise source impedance. Based on the principle of SPs, the source impedance is measured through transmission and reflection parameters from a vector network analyser when the circuit is shorted and loaded with noise source impedance, respectively. Moreover, amplitude-frequency performance and phase-frequency performance are optimised by using GA, and therefore the equivalent resistance, capacitance, and inductance are attained following the usual formula of the phase and amplitude of source impedance. This work made contribution for the design of the conducted EMI filter.

Attenuation of Conducted EMI for Three-Level Inverters Through PWM

This paper presents two typical modulations to reduce conducted electromagnetic interference (EMI) for three-level voltage-source inverters. The first modulation called variable switching frequency pulse-width modulation (VSFPWM) based on real-time current ripple prediction is used to reduce differential-mode (DM) EMI noise. This technique can make conducted EMI between kHz and MHz achieve great attenuation. The other method named zero common-mode (CM) PWM is used to decrease CM voltage and current. A comprehensive analysis and comparison between normal SVPWM and zero-CM PWM state that zero-CM PWM pays the prices of higher Total Harmowic Distortion (THD), serious neutral voltage unbalance, more switching loss and lower modulation index to achieve theoretical elimination of CM voltage. Then, combination of VSFPWM and zero-CM modulation is designed to avoid the disadvantages such as large switching loss produced by zero-CM PWM, and the new method has obvious predominance of reducing conducted EMI noise. Relevant experimental results validate the advantages of these modulations.

Research and Mitigation on EMI Noise for PV Converter

Photovoltaic (PV) systems have been widely used for power generation and renewable energy. Conducted electromagnetic interference (EMI) noise have generated, which affect the performance of other device and the grid. In the paper, the measurement uncertainty of artificial mains network (AMN) has been analyzed. The conducted EMI noise mechanism and noise mitigation methods have been proposed, including transistor filter and well grounding design strategies. The simulation and experiment results show that the conducted EMI noise generated by a certain convert can be suppressed well and pass EN 55011 and EN 55022 standards, thus good realization and validation.

Frequency-Domain Optimization of Digital Switching Noise Based on Clock Scheduling

The simultaneous switching activity in digital circuits challenges the design of mixed-signal SoCs. Rather than focusing on time-domain noise voltage minimization, this work optimizes switching noise in the frequency domain. A two-tier solution based on the on-chip clock scheduling is proposed. First, to cope with the switching noise at the fundamental clock frequency, which usually dominates in terms of noise power, a two-phase clocking scheme is employed for system timing. Second, on-chip clock latencies are manipulated to target harmonic peaks in specific frequency bands for the spectral noise optimization. An automated design flow, which allows for noise optimization in user-defined application-specific frequency bands, is developed. The effectiveness of our design solution is validated by measurements of substrate noise and conductive EMI (electromagnetic interference) noise on a test chip, which consists of four wireless sensor node baseband processors each addressing a distinct clock-tree-synthesis strategy. Compared to the reference synchronous design, the proposed clock scheduling solution substantially reduces noise in the target GSM-850 band, i.e., by 11.1 dB on the substrate noise and 12.9 dB on the EMI noise, along with dramatic noise peak drops measured at the 50-MHz clock frequency.

Filter Configuration and PWM Method For Single-Phase Inverters With Reduced Conducted EMI Noise

Electromagnetic interference (EMI) noise is one of the major issues during design of grid-tied power converters. A novel LCL filter topology for a single-phase pulsewidth modulation (PWM) rectifier that makes use of bipolar PWM method is proposed for a single-phase to three-phase motor drive power converter. The proposed topology eliminates high dv/dt from the dc-bus common-mode (CM) voltage by making it sinusoidal. Hence, the high-frequency CM current injection to the ground and the motor-side CM current are minimized. The proposed filter configuration makes the system insensitive to circuit nonidealities such as mismatch in inductors values, unequal turn-on and turn-off delays, and dead-time mismatch between the inverter legs. Different variants of the filter topology are compared to establish the effectiveness of the proposed circuit. Experimental results based on the EMI measurement on the grid side and the CM current measurement on the motor side are presented for a 5-kW motor drive. It is shown that the proposed filter topology reduces the EMI noise level by about 35 dB.

A New $LCL$-Filter With In-Series Parallel Resonant Circuit for Single-Phase Grid-Tied Inverter

When designing a higher order output power filter for a transformerless grid-tied converter using pulsewidth modulation (PWM), the requirements on the leakage current, the electromagnetic interference (EMI) noise, and the harmonics of the grid-injected current should be addressed. For an LCL-filter-based single-phase grid-tied full-bridge inverter system, it is possible to decrease the total inductance as well as the size and the cost, if the harmonic currents around the switching frequency can be fully suppressed. In this paper, the grid-injected current harmonics and the conducted EMI noise are investigated for the conventional LCL-filter-based system. Based on this, a modified LCL-filter topology using an extra parallel LrCr resonant circuit is proposed to reduce the total inductance value, without increasing the capacitive reactive power. The validity is verified through the experiments on a 500-W 110-V/50-Hz prototype.