A Fast and Precise Method for Modeling EMI Source in Two-Level Three-Phase Converter

Electromagnetic interference (EMI) filter design aspect of high-density plasma cutting power supply is developed. Converter components are accurately modeled, with parasitic elements extracted to reveal their impacts on the EMI noises. Circuit simulations are used to analyze and minimize the EMI noises. Conducted EMI noise measurement and filter design of this power supply has been achieved while successfully satisfying the FCC class B limits in the frequency range from 150 kHz to 30 MHz. The analyses and experiment results show that the designed filter guarantees that the required attenuation is achieved

This paper describes ceramic feedthrough capacitor electromagnetic interference (EMI) broadband filter design and installation techniques that generally make cardiac pacemakers and implantable cardioverter defibrillators (ICDs) immune to EMI from handheld wireless communication devices (including cellular phones) and other RF emitters. A typical cardiac pacemaker with four platinum lead wires which egress through a titanium housing (can) via a gold brazed alumina hermetic terminal is studied. The titanium can is seam welded to act both as an electromagnetic shield and a hermetic barrier to protect the internal components from body fluids. These lead wires, which normally carry the pacing pulses and sense cardiac activity, can also act as an antenna and conduct undesirable RF carrier signals (such as EMI induced by cellular phones) to sensitive internal electronic circuits. The EMI filter design described herein effectively de-couples and shields such signals over a broad frequency range before they can enter into the titanium can and disrupt normal pacemaker or ICD functions.

The identification and localization of large-range, wide-band electromagnetic interference (EMI) sources have always been both costly and time-consuming. The measurements at different times and places are often required before a typical system can locate a target. In this paper, we proposed a 2D electromagnetic imaging system to localize interference sources and identify the EMI frequency in real time. In this system, an offset paraboloid with a diameter of three meters is designed for large-range EMI imaging, while a multi-channel digital signal acquisition system is developed for wide-band EMI localization. The located interference source is segmented by the maximum entropy method based on particle swarm optimization, and the modified generalized regression neural network (MGRNN) is applied to identify the EMI frequency effectively by excluding misleading effects of outliers. The experiment which has been completed on our dataset indicates that our approach not only increases accuracy by 5% compared with the standard generalized regression neural network approaches for identification, but also exerts a large-range wide-band localization of the EMI source detection method.

The switching frequency of the boost power factor correction (PFC) converter operating in critical conduction mode (CRM) varies in a line cycle, making the conducted electromagnetic interference (EMI) spectra of the converter appear great differences under different input voltage and load conditions. The EMI filter should be designed according to the worst conducted EMI spectrum of the converter, so as to suppress the conducted EMI of the converter to be lower than the standard limits under all working conditions. This paper analyzes the characteristics of the common-mode (CM) and differential-mode (DM) noise spectra of the CRM boost PFC converter, and discusses the effects of the varied switching frequency on the peak, quasi-peak (PK), and average (AV) conducted EMI spectra. It is revealed that, for the conducted EMI limits defined in EN55022 class B, which are specified within 150 kHz to 30 MHz, the EMI filters required for suppressing the QP spectra of the conducted EMI of the CRM boost PFC converter are larger than that for suppressing the AV spectra, and the QP values of the conducted EMI under all working conditions are lower than a certain maximum boundary. The input voltage and load conditions for the worst CM and DM noise spectra of the converter are derived in this paper, thus the repetitive measurements and numerical calculations are avoided. A CRM boost PFC converter prototype is fabricated, and the evaluation of the measured conducted EMI spectra and the EMI filter design example verified the theoretical analysis.

Electromagnetic interference (EMI) filters play an important role in restraining conducted EMI, affected by the impedance of the noise source, and the load, the performance of the EMI filter is often poor. In order to resolve the mismatch problem of passive filter, this paper proposes an EMI filter based on impedance matching. Based on the fundamental design principle of the passive filter, the design of passive EMI filter is analysed and discussed at first.Then, on the basis of the theoretical foundation, more detailed and practical design is given further. By using the method of the matching network, the design of passive EMI filter under the worst circuit stances is emphasised. Finally, the design result is emulated and analysed, the proposed EMI filter idea is verified by the simulation result.

This paper presents a systematic and comprehensive approach for differential mode (DM) electromagnetic interference (EMI) filter design in a three-phase boost-type power factor correction (PFC) rectifier. Since the DM EMI filter forms a significant portion of the overall filter as well as converter volume, the reduction of DM filter component size is kept as a major objective in the filter design process in order to improve the power density. In addition to the objectives of volume optimization and conducted emission attenuation requirement to comply with the EMI standard, the filter design process also ensures a near-unity power factor operation with the optimal set of EMI filter parameters. To accomplish this, the paper analyzes the effect of EMI filter component selection on the overall lower order (1-100 kHz) frequency response, which is important for evaluating the dynamic response and stability. The results from the proposed design approach are validated through simulation, the DM Bode plot, and frequency response of the input current with and without EMI filter. As a proof-of-concept verification, the proposed EMI filter is implemented in a 4-kW three-phase boost-PFC prototype, which demonstrates minimal phase displacement (<;5°) of the input current.

An electromagnetic interference (EMI) filter design method for electric vehicle (EV) application is proposed in this paper. By transforming the design problem to an optimization problem, the filter volume, system disturbance level, inverter touch current and filter leakage current are taken into account simultaneously. A topology and order evolution approach is merged into the optimization algorithm based design procedure, thus the filter topology and its order can be determined automatically.

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;There are many electronic devices in electric vehicle (EV), making its electromagnetic compatibility (EMC) serious. Motor drive system is the main interference source of EV, whose electromagnetic interference (EMI) is much worse than conventional vehicle. In this paper, the motor drive system of EV was mainly researched, and a co-simulation method was proposed: control system and motor model were established with Matlab, and the equivalent circuit model of inverter and the cable model were established with Saber. By this way, a complete motor drive system model for conductive EMI was obtained. This modeling method can not only accurately establish the EMI sources and coupling paths, but can simulate the control strategy and operating conditions. In order to study the influence of Inverter Modulation Mode on the common mode (CM) EMI of motor drive system, firstly equivalent circuit model of inverter was established with Saber, and control system of motor drive system using space vector pulse width Modulation (SVPWM) and permanent magnet synchronous motor (PMSM) was established with Matlab. Then the CM current at the output of inverter was experimented, and the accuracy of the model was verified by comparing the simulation with the experiment. Finally, the effect of random zero-vector distribution PWM (RZPWM) and random switching frequency PWM (RSFPWM) on CM EMI was researched. Influence of operating condition on CM EMI was also studied. The research work of this paper has a certain theoretical guiding significance for the EMI prediction of the motor drive system of EV.&lt;/div&gt;&lt;/div&gt;

Electromagnetic Interference (EMI) is generated and mitigated in power converters. EMI problems are related to high-speed power converters. This article focuses on conducted electromagnetic interference in adjustable-speed drive (ASD) systems. The electromagnetic compatibility of three-phase/level grid-connected drive inverters is investigated. The test setup is built per the CISPR16-1–2 standard, and the interferences produced from the inverter to the grid are measured. The main dependencies of conducted emissions of a power inverter, changes in the length/shape of main cables, and motor speed have been investigated under load and no load conditions. Factors affecting EMI performance and filter design issues will be addressed. A statistical approach to quantifying the frequency domain impact of conducted emission noise created on the three-phase system by operating various emission sources. Fast Fourier Transform (FFT) was applied for time–frequency domain conversion, and to evaluate with a statistical approach Minitab software was used. Then, a filter design is created to prevent these interferences from being conducted to the grid. Also, the noise attenuation of the EMI filter has been validated in the simulation. Briefly, this study fills in the blanks of uncertainties involved in measuring three-phase emissions, which helps the engineers at the design stage of three-phase converters.

This paper describes a frequency domain approach to the prediction of differential mode (DM) conducted electromagnetic interference (EMI) for a three-phase inverter at the early design stage. The approach is able to calculate the DM conducted EMI with more accurate noise source and parasitic path identification. The DM noise sources are identified as three device switching current and their frequency domain expressions are derived according to inverter operating principle. The parasitic components are identified using FEM analysis. The calculated DM EMI result is compared with experimental data and it can predict the high frequency resonant peak precisely. It is indicated that the frequency domain analysis with accurate noise source and parasitic modeling is an effective tool for DM EMI prediction for three-phase inverter circuit.

Today's complex electronic systems require that the Design Engineers pay particular attention to the side effects of Electromagnetic Interference (EMI) upon system operation. To assist the Design Engineer in considering these additional parameters, the Electromagnetic compatibility (EMC) Engineer must furnish useful tools to enable such considerations to be in the basic design. Through the use of the time-shared computer, which is available through a teleprinter terminal, the complexity and drudgery of EMI Data reduction, prediction, and analysis can be significantly reduced when suitable programs are available. This paper presents two typical programs and describes the major operations and operator-computer interplay. The first program describes the solution to a filtering problem and incorporates Fourier analysis, specification limits, desired values of L, C, and circuit values for source and load impedances. In addition to determining the filter insertion loss as a function of frequency, the program translates these requirements into a 50 ohm system to expedite the purchase of ready-made filters. The second program presented may be used in the reduction of EMI data resulting from broadband conducted interference testing using a current probe. The operator may elect several options during the progress of the program and is requested to enter data readings. Upon completion, the computer prints out a complete data sheet and a graph of the values (data readings plus current probe factors) and specification limits versus frequency. Tilt levels (values greater than the specification limit) are included in the data table.

Protecting COVID-19 Vaccine Transportation and Storage from Analog Cybersecurity Threats

Underground Electro Magnetic Interference (EMI) has become so serious that there were false alarms in monitoring system, which induced troubles of coal mine safety in production. In order to overcome difficulties caused by the explosion-proof enclosure of the equipments and the limitation of multiple startup and stop in transient process during EMI measurement, a novel technique was proposed to measure underground EMI distri- bution indirectly and enhance Electromagnetic Campatibility(EMC) of the monitoring sys- tem. The wavelet time-frequency analysis was introduced to underground monitoring sys- tem. Therefore, the sources, the startup time, duration and waveform of EMI could be as- certained correctly based on running records of underground electric equipments. The electrical fast transient/burst (EFT/B) was studied to verify the validity of wavelet analysis. EMI filter was improved in accordance of the EMI distribution gotten from wavelet analysis. Power port immunity was developed obviously. In addition, the method of setting wavelet thresholds was amended based upon conventional thresholds in the wavelet filter design. Therefore the EFT/B of data port was restrained markedly with the wavelet filtering. Coor- dinative effect of EMI power and wavelet filter makes false alarms of monitoring system reduce evidently. It is concluded that wavelet analysis and the improved EMI filter have enhanced the EMC of monitoring system obviously.

Active electromagnetic interference (EMI) filter is a feasible and effective suppression technology for switching mode power supply (SMPS) system. The traditional active EMI filter (AEF) suppresses EMI by sensing EMI signal and generating cancelation EMI by the controlled high-frequency operational amplifier. The filtering performance not only depends on the high-open-loop gains of the operational amplifier but also on its low-output impedance of AEF. However, obtaining sufficiently low-output impedance of AEF is very difficult in a controlled filtering frequency band. To cope with it, a filtering topology of AEF based on impedance modulation for SMPS is proposed in this article. The proposed active trap EMI filter (ATEF) can trap the EMI current at the filtering frequency band with a sufficiently low-output impedance by introducing a negative impedance circuit. Finally, the impedance and the filtering performance are evaluated on a 48 W SMPS, and experimental results show that the proposed ATEF can effectively suppress the conducted EMI generated by SMPS.

A PWM inverter fed ac induction motor drive system capable of suppressing all the adverse effects of PWM inverter is developed in this paper. A passive electromagnetic interference (EMI) filter is proposed, designed, and tested for a 4-kW drive system, is characterized by sophisticated connection of two small passive filters can compensate for common mode voltages produced by PWM inverter and can suppress leakage current. An equivalent common-mode circuit for the drive system equipped with the EMI filter is derived from experimental waveforms along with theoretical discussions verifies that the EMI filter is viable and effective in eliminating all adverse effects of PWM inverter.