Low-Frequency Conducted Emission of Electromagnetic Interferences in Ship Power Systems

Ship power systems are characterised by a comparatively high level of various power quality disturbances, such as voltage deviations, frequency deviations, voltage waveform distortions and sometimes voltage unbalance, which exert a detrimental effect on energy receivers. Among other things, power quality disturbances may cause an extraordinary increase in power losses occurring in on-board induction motors as well as ineffective utilisation of their mechanical output power. In this study, the results of empirical research which demonstrates how power quality disturbances in real ship microgrids affect induction motors are shown. The results of power quality monitoring in ship power systems from the point of view of the energy-efficient operation of induction motors are presented for various vessels and operating conditions. Recommendations concerning the revision of power quality standards and rules are elaborated to provide more energy-efficient ship operation.

The fast switching speed of high voltage silicon carbide (SiC) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) can achieve high power density but are accompanied by significant common-mode (CM) current. The CM current propagates through the parasitic capacitor between the floating electrical potential and the grounded baseplate, which leads to conduct electromagnetic interference (EMI) noise. This paper focuses on the CM EMI mitigation in power module packaging. A 10kV/60A module configuration is proposed and optimized toward high insulation, low CM noise, and a convenient module-system interface. Stacking DBC substrates structure is utilized for the device-baseplate insulation, which provide a vertical structure for EMI shielding and paths for EMI mitigation. Furthermore, an extra pattern is etched on the middle layer of stacking DBC substrates for parasitic capacitance reduction. The EMI propagation loop difference between the conventional stacking DBC substrates and the proposed structure with the middle layer pattern are compared. The optimized configuration and middle layer pattern offer a significantly reduced grounding capacitance by 37%.

In this paper, a 12-V 1-kW permanent-magnet ac motor drive is tested extensively at a wide frequency range, and the frequency spectra are partitioned for identification of noise sources and their propagation paths. Switching characterization of the power MOSFET and its body diode reverse-recovery characterization are evaluated for circuit modeling. The parasitic components and common mode path are identified and measured with the time-domain reflectometry (TDR) method. The inverter circuit model is then constructed with major parasitic inductance and capacitance in device modules, passive components, leads, and interconnects. To verify the validity of the inverter model, a comparative study is performed with computer simulations and hardware experiments. The fundamental mechanisms by which the electromagnetic interference (EMI) noises are excited and propagated are analyzed, and the significant roles of parasitic elements coupling with device switching dynamics in EMI generation are examined. The results indicate that the identification of parasitic inductance through TDR measurement helps verify the voltage spike during turn-off, or vice versa. The conducted EMI noise caused by parasitic components of bus capacitor, dc bus, and devices is proven to be identifiable with the characterization and simulation techniques used in this paper.

SUMMARY This paper proposes spread-spectrum clock modulationalgorithms for EMI reduction in digitally-controlled DC-DC converters.In switching regulators using PWM, switching noise and harmonic noiseconcentrated in a narrow spectrum around the switching frequency cancause severe EMI. Spread-spectrum clock modulation can be used to min-imize EMI. In conventional switching regulators using analog control it isvery difficult to realize complex spread-spectrum clocking, however thispaper shows that it is relatively easy to implement spread-spectrum EMI-reduction using digital control. The proposed algorithm was verified usinga power converter simulator (SCAT). key words: PWM control, spread-spectrum clock modulation, EMI,digitally-controlled DC-DC converter 1. Introduction Most portable electronic devices have low-voltage high-current power supplies using high-efficiency switching reg-ulators. However, the considerable switching noise (andEMI) that switching regulators produce is a big demerit.EMI-related regulations are becoming more severe [1]. Reg-ulations prescribe limits on the generation of Electromag-netic Interference (EMI) and also noise-tolerance or Elec-tromagnetic Susceptibility (EMS) requirements; the combi-nation of both EMI and EMS is called EMC (Electromag-netic Compatibility). In many countries it is illegal to sellelectrical and electronic devices that do not comply with lo-cal EMC standards (in many cases devices must be type-approved, or tested and certified as complying). In mostconventional switching regulators, shielding and filteringare used to reduce EMI. While shielding and filtering areeffective ways of reducing noise, penalties associated withthis approach include the cost of transformers and coils andthe size/weight of shielding.We considered, as an alternative to extensive shield-ing and filtering, how to reduce EMI by switching regu-lator control-module design changes. After examining thepossible application of digital control systems with spread-spectrum technology [2]–[5] to analog-controlled switching

Using commercial off the shelf (COTS) computing equipment in military aircraft applications may cause harmful electromagnetic interference (EMI) to other on-board systems, including communication and navigation equipment. An electromagnetic compatibility (EMC) design approach to successfully integrate COTS equipment into an existing military aircraft is described. The following system design and development steps are outlined: (1) requirements definition, (2) preliminary EMC analysis, (3) EMC control measure design, (4) COTS equipment EMI characterization tests, and (5) system level EMC verification.

This paper describes the investigation of Common Mode (CM) noise and Differential Mode (DM) noises in Dual Active Bridge (DAB) converter applied in Electric Vehicle (EV) in order to reduce the Electromagnetic Interference (EMI) that occurs in EVs. The DAB converter is designed and simulated using a spice simulator and the CM and DM noises from the converter circuit were measured as per the CISPR 25 EMI Standard. Based on the simulated results, the attenuation level of noise was calculated and used to design the components of the EMI filter. The design was validated using the simulation findings after the converter are created, tested and the experimental results compared. Based on the results and discussion, recommendations are made in this paper to reduce EMI in converters used in EV. Especially, suggestions to reduce the common mode and differential mode noises produced by Dual Active Bridge converters employed in EV were given as per the CISPR 25 standard.

<div class="section abstract"><div class="htmlview paragraph">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.</div></div>

Electromagnetic Interference (EMI) noise is one of the major issues during the design of the grid-tied power converters. Presence of high dv/dt in Common Mode (CM) voltage, excites the parasitic capacitances and causes injection of narrow peaky current to ground. This results in high EMI noise level. A topology consisting of a single phase PWM-rectifier with LCL filter, utilising bipolar PWM method is proposed which reduces the EMI noise level by more than 30dB. This filter topology is shown to be insensitive to the switching delays between the legs of the inverter. The proposed topology eliminates high dv/dt from the dc-bus CM voltage by making it sinusoidal. Hence, the high frequency CM current injection to ground is minimized.

Adjustable speed AC drive (ASD) manufacturers recently migrated from bipolar junction transistor (BJT) semiconductors to insulated gate bipolar transistors (IGBTs) as the preferred output switching device. The advantage of IGBTs is that device rise/fall time switching capability is 5-10 times faster, resulting in lower device switching losses and a more efficient and smaller drive package. However, faster output dv/dt transitions and higher drive carrier frequencies increase the magnitude of common mode (CM) electrical noise and electromagnetic interference (EMI) problems. Experience suggests all PWM drives with steep fronted output voltage waveforms have these problems. This paper provides a basic understanding of EMI generated by these drives solutions to control EMI, as well as regulation standards on allowable conducted and radiated emissions to insure a successful drive system installation.

Switch Mode Power Supplies (SMPS) are extensively employed in fields such as telecommunications, information technology, and electric vehicles, where energy efficiency is increasingly demanded. Modern SMPS designs prioritize compact size, high power density, and optimal efficiency to meet these requirements. The LLC resonant topology, commonly utilized in the DC/DC conversion stage with planar transformers, enables operation at high frequencies (hundreds of kHz) and facilitates soft switching across the full load range. However, a significant drawback of this topology is electromagnetic interference (EMI), particularly common-mode (CM) noise, which arises from high switching frequencies and parasitic capacitance in the components. This challenge is further exacerbated by the use of planar transformers. This study presents a CM noise model for the Half-Bridge LLC (HB-LLC) converter based on a two-capacitor transformer representation, aiming to analyze CM noise behavior and investigate practical, cost-effective methods for its reduction.

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

This paper focuses on the problem of conducted electromagnetic interference (EMI) in multi-load magnetic resonant wireless power transfer (WPT) system. A high frequency equivalent model is established to analyze the common mode (CM) and the differential mode (DM) conducted EMI by simulations in Saber. The comparison of CM interference has been made when the number of loads changing and the load impedances becoming unbalanced at the primary side. The circulation of the CM interference at the load side between two loads by coupling capacitors of resonant coils have been discussed. Filtering methods are put forward for multi-load magnetic resonant WPT system to reduce the CM interference. Both simulations and experimental results verify the complexity of EMI conditions and the significant effect of the filter.

Active magnetic bearing (AMB) with power electronics drive is an important technology for high-speed rotational machinery suspension. There were seldom literatures concerning the common mode (CM) electromagnetic interference (EMI) problems of the AMB system. In this article, we found that the power electronic converter used for AMB control will not only bring EMI to the devices but also influence the performance of the levitation control. To cope with this problem, the parasitic paths of the leakage currents in the five-degrees-of-freedom AMB system were analyzed. The control principle and the novel zero CM PWM (ZCMPWM) strategy for the AMB driven by a four-leg converter were presented to suppress the CM EMI. Experiment has been done on an AMB-based compressor. The proposed method can significantly reduce the CM EMI caused by the AMB controller and improve the performance of levitation.

The large dv/dt and di/dt outputs of power devices in wireless charging system (WCS) in electric vehicles (EVs) always introduce conducted electromagnetic interference (EMI) emissions. This paper proposes a mitigation conducted emission strategy based on transfer function from a direct current fed (DC-fed) WCS for EVs. A complete test for the DC-fed WCS is set up to measure the conducted emission of DC power cables in a frequency range of 150 kHz–108 MHz. An equivalent circuit with high-frequency parasitic parameters for WCS for EV is built based on measurement results to obtain the characteristics of conducted emission from WCS. The transfer functions of differential mode (DM) interference and common mode (CM) interference were established. A judgment method of using transfer functions to determine the dominated interference mode responsible for EMI is proposed. From the comparison of simulation results between CM or DM and CM+DM interference, it can be seen that the CM interference is the dominated interference mode which causes the conducted EMI in WCS in EVs. A strategy of giving priority to the dominated interference mode is proposed for designing the CM interference filter. Finally, the conducted voltage experiment is performed to verify the mitigation conducted emission strategy. The conducted voltage of simulation and experiment is decreased respectively by 21.17 and 21.4 dBμV at resonance frequency 30 MHz. The conduced voltage at frequency range of 150 kHz–108 MHz can be mitigated to below the limit level-3 of CISPR25 standard (GB/T 18655-2010) by adding the CM interference filters.

Motors in Adjustable Speed Drive (ASD) systems are the major sources of conducted Electromagnetic Interference (EMI), and they are mainly the Common-Mode (CM) currents and voltages. Compliance with Electromagnetic Compatibility (EMC) standards is of utmost importance when maintaining system reliability in the face of ever-stricter Electromagnetic Compatibility standards in the industrial sectors. This work presents the first systematic experimental evaluation of CM impedance in Split Phase Induction Motors (SPIMs) in a wide frequency range (100 Hz to 100 MHz). Unlike prior studies that were limited to either a differential-mode analysis or limited frequencies in the experiment, the study provides comprehensive CM impedance data of two different SPIM setups, explaining resonance and anti-resonance behaviors that have direct implications on EMC performance. It is experimentally proven that high impedance designed motors significantly reduce CM current transfer, thus reducing EMI emissions and enhance EMC compliance. Particularly, the impedance peak of SPIM (I) was 8k at 100 MHz that translated to a 45% decrease in CM current and −15 dB attenuation of conducted EMI compared to SPIM (II). The resonance and anti-resonance frequencies determined the influence of motor architecture on its susceptibility to EMI. As a result, the findings provide prescriptive design information to the optimization of SPIMs in applications, for example, industrial automation and electric vehicle platforms, where very high EMI mitigation levels are of crucial importance.