EMI Mitigation Research Articles

Audible Noise and EMI Mitigation in IPMSM Zero or Low-Speed Sensorless Drive With Randomized Low-Frequency Pulse Voltage Injection

Audible Noise and EMI Mitigation in IPMSM Zero or Low-Speed Sensorless Drive With Randomized Low-Frequency Pulse Voltage Injection

Adaptive switching frequency PWM method of SiC inverters for EMI mitigation

Adaptive switching frequency PWM method of SiC inverters for EMI mitigation

A Novel Deep Reinforcement Learning Methodology for EMI Mitigation in Multi-Scenario Pinmap Design

A Novel Deep Reinforcement Learning Methodology for EMI Mitigation in Multi-Scenario Pinmap Design

On Spread Spectrum for DC Grids: Low-Frequency Conducted EMI Mitigation and Signal Integrity Disruption in Serial Communication Links

This article addresses the effects on nearby communication systems when spread spectrum modulation techniques are used for a dc–dc power converter. These interactions can be found in modern smart grids and automotive power networks in which the combination of communication links, switching power supplies, and long cables play a major role in electromagnetic interference issues at low frequencies below 150 kHz. Spread spectrum modulation, with its different variations (sine and random) are widely used to comply with electromagnetic compatibility standards. However, there are certain effects that can be harmful to either the converter or the rest of the power network. These effects happen at different frequencies and for different parameters used in the modulation algorithm. With the aim to standardize an assessment procedure, measurements are made to determine the interference created by an SiC-based dc–dc converter. The peak index of a CISPR-16 EMI receiver is used to evaluate the behavior in the frequency domain while a study in serial communication disruption is undertaken using mean and quantile values from a bit error rate tester.

EMI Mitigation of GaN Power Inverter Leg by Local Shielding Techniques

This paper presents local shielding techniques applied to a half-bridge inverter leg with the aim to reduce the common mode (CM) current noise at converter's DC input. The research study is conducted for 650V Enhancement mode Gallium Nitride (GaN) power transistor switches. Main contributors of parasitic capacitances referred to the inverter-leg middle point node are identified. Then, shielding solutions are proposed to reduce CM current emission by these capacitances. Respecting the precautions concerning the isolation of CM currents of the half-bridge inverter leg, the electromagnetic compatibility measurement setup is developed. Experimental step-by-step addition of local shielding copper layers to different contributors of middle point capacitance shows progressive attenuation of CM noise spectra.

Coupling Path Visualization and EMI Mitigation for Flyover QSFP Connectors

In this article, the energy parcels concept is used to reveal radiation physics and coupling in the entire structure of flyover quad form-factor pluggable (QSFP) interconnection. Flyover QSFP has better signal integrity than legacy surface mounted printed circuit board QSFP technology. To understand electromagnetic interference aspects, a simulation model was built and correlated to measured total radiated power (TRP) for common mode and differential mode excitations for a frequency range of 1-40 GHz. Further, the energy parcels and their trajectories concept were applied to visualize the coupling path by tracking back the energy parcels from outside of the chassis (quiet side) toward a host board inside the chassis (noisy side). Then, high-density regions of energy parcel trajectories guide where to place the absorbing material efficiently and appropriately. Two locations were examined by filling them with electromagnetic lossy material and improvement was validated by TRP simulation and measurement.

A Review of the EMI Mitigation Techniques in Power Converters

Electrical and electronic technology is being widely deployed which have both beneficial and pervading impacts on day-to-day life. Electromagnetic Interference is the most prominent impact which affect performance of devices. Consequently, dealing with EMI has become a responsibility for engineers and scientists. EMI can emanate from natural and man-made sources. Power converters are the main man-made source, which produce EMI due to its high frequency switching action. To address EMI, electromagnetic compatibilty(EMC) standards are setforth. EMI mitigation measures commonly used are employing filters and electromagnetic shielding devices. Due to various drawbacks pertaining to its exogeneity, other methodologies are put forward to make device adhere to EMC standards. This paper focuses on providing an overview on the state of the art of traditional EMI suppression technologies,the use of chaos theory ,chaos control and spread spectrum techniques to reduce EMI. The paper envisages on PWM modulation techniques to mitigate EMI in power converters by spreading EMI peaks over a wide frequency range to weaken its strength(dB/Hz). These modulation techniques include Chaotic modulation, and Spread spectrum frequency modulation(SSFM).

Investigating the EMI Mitigation in Power Inverters Using Delay Compensation

Electromagnetic emissions (EMEs) of electric and electronic units should comply with national and international standards. Software approaches to reduce the conducted EME are preferable, since they do not require additional on-board hardware. Many techniques have been developed with different levels of efficiency. This paper aims to analyze a new software approach to mitigate the conducted emissions of three-phase power inverters, focusing on those used to drive brushless DC motors. This has been done reducing the conducted electromagnetic interferences common mode (CM) component through software compensation of parasitic delays. The technique is verified both analytically and experimentally, and its performances have been compared to the spread spectrum modulation (SSM) ones. The proposed approach shows better performances with respect to SSM below 24 MHz. The results confirm the effectiveness of the delay compensation technique in terms of CM conducted emissions reduction. Moreover, the proposed approach has no drawbacks on safety and it does not present reductions in the inverter efficiency.

EMI Coupling Paths and Mitigation in a Board-to-Board Connector

Cage connectors for optical subassembly I/O modules have been identified as one of the main coupling paths in an optical link at the front-end of switches and routers. In the study presented herein, the simulation model used to study electromagnetic interference coupling physics and mitigation of the optical cage connector was corroborated by comparing the measured and simulated results for the total radiated power (TRP). Currents on the adjacent ground references to the differential signal conductors caused half-wave resonant peaks in the TRP response in the frequency range of 4–18 GHz. At frequencies from 18 to 28 GHz, both full-wave simulation and analytical formulas indicate that the radiation results primarily from the currents on the signal traces. The radiation from the optical cage connector was suppressed with absorbing materials, and the coupling path was verified, together with the optical cage and module enclosure.

EMI-FREE DC-DC BUCK CONVERTER FOR AEROSPACE APPLICATIONS

Modern electronic systems require tiny, high-qualit y, less weight, reliable and efficient power suppli es. Linear power regulator whose principle of operation is based on a voltage or cur rent divider is inefficient sometimes. This is beca use their output voltage is smaller than the input voltage and also they require low fr equency (50 or 60 Hz) transformers and filters. The ir main area of application is at lower power levels; but at higher levels, switching regulators are used. They use semiconductor switch es for the purpose of turning off and on states. Because there is a power loss in tho se states, switching regulators can achieve high en ergy conversion efficiencies and that is the major advantage. Power electronic syste ms such as switching power supplies are accounted anoise source for their sensitive circuits. EMI caused by the converters ca n disturb the normal operation of the supply and ot her systems by coupling with the nearby devices. Hence the overall performance of th e system is reduced Major focus is done on the rad iated EMI mitigation for the power converters in which the main standard is the compliance with the EMC standard to ensure the prop er operation of the converter and nearby systems. Buck converter is a sconverter which is one of the most widely used topologies among the different DC-DC topologies. In the forward topology , we are providing the galvanic isolation which iso lates the functional sections of the electrical systems to prevent the current flow. No direct conduction is permitted. In this paper, different topologies are discussed and implemented which can reduce the Radiated Emiss ion (RE) and MILSTD 461/462 will be the underlying EMC standard.

Experimental Study on Conducted EMI Mitigation in SMPS using a Novel Spread Spectrum Technique

Switched mode power supplies (SMPS) are power electronic circuits extensively used in a wide range of applications. High frequency switching operation of SMPS causes electromagnetic emissions and has the potential to interfere with system operation, which in turn has an impact on system performance. This makes electromagnetic compatibility (EMC) an important concern. In this paper, a new and simple spread spectrum technique is proposed by modulating chaotic pulse position modulation (CPPM) and pulse width modulation (PWM). The resulting CPWM is implemented to reduce the conducted EMI in SMPS. The proposed method is found to be effective in reducing conduction EMI. The effectiveness and simplicity of the proposed method on spreading those dominating frequencies is compared to the EMI mitigation technique using an external chaotic generator. Finally, the levels of conductive EMI with standard PWM, CPWM with an external chaos generator and the proposed method are experimentally verified to comply with the CISPR 22A regulations. The results confirm the effectiveness of the proposed method.

Classification and Comparison of EMI Mitigation Techniques in Switching Power Converters - A Review

Power electronic systems such as switching power supplies are accounted as noise sources for other sensitive circuits. EMI caused by power converters can disturb the normal operation of the converter and other adjacent systems. Major research is concentrated on EMI mitigation for power converters in which the main concern is compliance with EMC standards to ensure proper operation of converters and nearby systems. This paper reviews EMI reduction techniques related to switching power converters with emphasis on the conducted EMI. A comprehensive review of significant research works is performed and various methods are thoroughly discussed and compared. Also, a classification of methods is presented. Moreover, converter prototypes are realized which contain several EMI mitigation techniques and their effects are presented via experimental results.

Impact of Variable Switching Frequency over Power Loss on Converter Topologies

This paper compares different topologies of DC-DC converters for levels of mitigation of EMI using a RCD snubber for each. This paper proposes the design and simulation of a Buck, Cuk and the Boost converter using the software PSPICE. The circuit was constructed on PSPICE and the output voltage of the converter is simulated for different switching frequency. The simulated output was then studied for different switching frequencies keeping duty cycle constant, and EMI was found in the output due to switching of the MOSFET. In order to minimize this interference a RCD snubber circuit was designed in PSPICE across the MOSFET of the converter. The output and simulations of these three topologies were then studied in comparison to the output of these converters without snubber circuit.

Power bus signal integrity improvement and emi mitigation on multilayer high-speed digital pcbs with embedded capacitance

The continuous technology trend in the telecommunication market toward higher operating frequencies and high processing performances will give rise to new sophisticated chip sets, processors, and RF transceivers which will demand new feature to the PCB designs. As the complexity of the integrated circuits increases, signal integrity (SI) and electromagnetic compatibility (EMC) become key elements in the board design process. This paper analyzes the beneficial effects that a thin dielectric material between a pair of power and ground layers (embedded capacitance) has both in reducing power bus resonance amplitudes (SI approach) and radiated emissions (EMC approach) as well. Scattering parameter measurements carried out on the power bus of two production boards are presented and correlated with the electric field strength measurements conducted on the same boards in a semianechoic chamber.

EMI mitigation with multilayer power-bus stacks and via stitching of reference planes

General methods for reducing printed circuit board (PCB) emissions over a broad band of high frequencies are necessary to meet EMI requirements, as processors become faster and more powerful. One mechanism by which EMI can be coupled off a PCB or multichip module (MCM) structure is from high-frequency fringing electric fields on the DC power and reference planes at the substrate periphery. An approach for EMI mitigation by stitching multiple ground planes together along the periphery of multilayer PCB power-bus stacks with closely spaced vias is reported and quantified in this paper. Power-bus noise induced EMI and coupling from the board edges is the major concern herein. The EMI at 3 m for different via stitch spacing and layer thickness is modeled with the finite-difference time domain (FDTD) method. Design curves and an empirical equation are extracted from a parametric study to summarize the variation of the radiated EMI as a function of layer thickness and stitch spacing.

A note on the mitigation of EMI caused by wide-angle radiation from parabolic-dish antennas

Two methods of reducing the wide-angle radiation levels of a prime-fed parabolic dish to mitigate the EMI it causes are concisely described: by combining both methods a substantial reduction in EMI can be achieved.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>