1,721,169 research outputs found
Voorspelling van functionaliteit op de lange termijn en elektromagnetische compatibiliteit van elektronische apparaten
No full textIt is a challenge to ensure the long-term functionality and EMC compliance of electronic devices during their foreseen lifespan. In this PhD-thesis, a continuous monitoring method is proposed to overcome the drawbacks of the conventional discontinuous method. A dedicated measurement setup is implemented to automatically conduct the accelerated ageing process and characterization. The advantages of the proposed method are verified by carrying out an accelerated ageing test where two types of film capacitors with Polyethylene terephthalate (PET) and Polypropylene (PP) dielectrics are selected to undergo thermal and electrical stresses. Second, a prediction model is developed based on a deep neural network to assess the capacitors' parameters, such as capacitance and equivalent series resistance (ESR). A new stop-criterion is proposed to reduce the measurement time of the accelerated ageing process (in the case of this PhD-thesis from 1000h to 200h). Third, a novel full-parameter ageing modelling approach of capacitors is developed based on complex impedance analysis. More parasitic parameters are taken into account compared to classical capacitor models. The ageing characteristics of all the proposed 7 parameters are experimentally studied and modeled in an inverse power law. The frequency response deviations of RC EMI filters are simulated based on the complex impedance analysis afterwards. Fourth, the ageing effects on the functionality and EMC deviations of LDO regulators are experimentally analyzed by a proposed automated setup. The prediction of ageing-induced EMC evolutions is modeled based on a hybrid convolutional neural network and long short-term memory architecture.status: Publishe
Software Strategieën om de Immuniteit van Programmeerbare Ingebedde Systemen tegen Storingen te Verbeteren
No full textProgrammable Embedded Systems form the cornerstone for the rising challenges in the next industrial revolution of cyber physical systems where everything gets connected, data is interchanged and decisions are made by programmable controllers. Application areas are mobility, manufacturing, smart energy consumers, health and elderly care. This implies a more frequent use of such systems in applications requiring high reliability in harsh environments. The rise in electronics significantly increases the probability of all kinds of disturbances, which is amplified by the decreasing intrinsic immunity. An important innovation in this research project, next to the optimization of the software design and automated test procedures, is the inclusion of software solution in the system, making it fault resistance or tolerant, which leads to a cost efficient solution in many situations. Such software solution is rarely applied, mainly because they are not widely known and need further research for effective implementation. A key objective of this research is to design and produce better and more reliable electronics with a lower development cost and a shorter time-to-market.status: Publishe
CoDEx-VFD: Controlled Disturbance Experiment - Variable Frequency Drive
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The CoDEx-VFD dataset provides time-series current measurements from a three-phase Variable Frequency Drive (VFD) system subjected to controlled electromagnetic disturbances (EMD). This dataset is designed for benchmarking and comparing anomaly detection algorithms in the context of electromagnetic compatibility (EMC). The data was collected under controlled laboratory conditions, with varying levels of disturbance severity and frequency, providing a valuable resource for researchers developing and evaluating methods for EMI detection and mitigation in electronic systems.
The dataset comprises 100 CSV files, each representing a single measurement run with different anomaly scenarios. Measurements include two directly measured phase currents along with a binary label indicating the presence or absence of an injected disturbance at each time point. The sampling rate is 2.5 MHz, providing high temporal resolution for capturing transient EMI events. Key experimental parameters, including disturbance characteristics and equipment details, are documented in the accompanying README file.
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Een axiale elektrische machine gebaseerd op een anisotroop gecontroleerd ferromagnetische composiet materiaal
No full textThis PhD describes a novel working principle for small electromechanical machines. The goal of the novel working principle is to increase the efficiency of these small electromechanical machines. In traditional electromechanical machines, a rotating magnetic field is used which is generated by time-varying currents in a set of stator coils. The stator Joule losses are responsible for 50 % of all losses when the power output is smaller than 1 kW.
Using a configuration combining permanent magnets and a composite of piezoelectric and magnetostrictive materials, the stator Joule losses are annihilated. The stator Joule losses are replaced with dielectric losses, but they take only 20 % of the input power. The composite of piezoelectric and magnetostrictive materials, forming the anisotropic controllable ferromagnetic composite, converts electrostatic energy into magnetic energy. The internal stress, obtained by the piezoelectric material, changes the magnetic behaviour of the anisotropic controllable ferromagnetic composite, giving it the function of a variable reluctance. Such variable reluctances combined with permanent magnets are implemented in a permanent magnet switched reluctance machine design, preferably an axial-flux machine.
The novel working principle is demonstrated using a magneto-mechanical finite element solver. This magneto-mechanical finite element solver is built around the improved energy based material model. The magneto-mechanical finite element solver consists of two solvers: (i) the radially symmetric magnetic solver and (ii) the Cartesian structural mechanical solver. The exploitation of radial symmetry in a dedicated 2D FE solver is new. The extension to the radially symmetric magnetic solver and the energy based material model were crucial to simulate and study the novel working principle.
Because the novel working principle is preferably implemented in an axial-flux machine, a radially symmetric 2D finite element solver is set up. The radial symmetry is non-standard, which requires the development of a set of dedicated shape functions. The requires shape function has a particular dependency on the radial coordinate in order to guarantee the partion-of-unity property, the consistency property and the convergence of the scheme. Such a dependency does not occur in the standard 2D Cartesian and the 2D axi-symmetric finite element solver.
The novel working principle uses the magnetostrictive material properties to convert magnetic energy into mechanical energy. This requires a proper understanding and simulation of the magneto-elastic material behaviour, which requires a physical material model instead of a phenological material model. The multi-scale approach suggested by L. Daniel et. al., is followed, because it still relies on microscopic approaches, but with a lower computational cost. This material model uses the micromagnetic theory based on a statistical distribution, which results in the anhysteretic behaviour. During a three month research visit to the RWTH Aachen, the hysteresis effect influenced by the stress has been implemented in this material model by introducing a new energy function, which models the hysteretic effect.
These achievements allowed the finite element simulation of the novel motor. The simulation confirms the initial assumptions and shows that the novel motor concept is a reliable alternative for small, traditional electric machines with stator coils. Moreover, the simulation shows that the performance of such a motor is comparable with a commercially available motor. This shows that the novel motor principle has a great potential.status: Publishe
Multipool-gebaseerde macromodellering voor EMC/EMI systeemanalyse
No full textNowadays, full-wave electromagnetic simulation tools are widely used in antenna design, and their employment in the assessment of electronic designs with respect to ElectroMagnetic Compatibility (EMC) has increased significantly over the past years, owing to an exponential increase in the integration of functionality and the clock rates of new designs. However, several developers are still rather reserved about their engagement to embrace the use of full-wave simulations. This trend can be attributed to four factors: (i) the investment cost of a full-wave simulation package, (ii) the expertise of R&D engineers, (iii) the limited availability of component models due to conflicts with confidentiality, and (iv) the computational cost of full-wave simulations. Due to the inherent complexity in today’s electronic designs and their clock rates, often dedicated computing servers are indispensable to manage the run-time and computational resources of full-wave simulations. In this thesis, we therefore aim to develop a macromodelling technique, focussed at system-level EMC analysis, which is independent of any full-wave solver, which has a very low computational cost, and which bears close resemblance to the topology of circuit simulators.
We obtain these goals by employing a Generalized Scattering matrix (GS-matrix) formulation based on a Spherical Wave Expansion (SWE) of the electromagnetic fields radiated by a Device Under Test (DUT). To derive efficiently such models, a new technique based on a reduction to Chebyshev polynomials is described, which allows one to compute models in optimal time with very high accuracy. In the scope of system-level EMC analysis, two new truncation criteria are formulated, either applicable to fields sampled in the near-field region of a DUT or to fields sampled in the far-field region of a DUT. Based on these truncation criteria, it is observed that in order to accurately model radiated fields close to a DUT, high-order SWEs are indispensable. Models which have been obtained using this approach are gathered in a common model library, which is accessible to a custom GS-matrix based simulation engine. This simulation tool is designed analogous to a circuit simulation topology, and thus allows its users to compute full-wave interactions between multiple DUTs by ‘plug-and-play’ with models available in a component library. Consequently, the presented framework also fits into existing circuit solvers, and significantly increases the accuracy of these solvers by taking into account full-wave phenomena. The additional background computations which form the core of the GS-matrix based simulation tool are optimized by observing that the necessary operators acting on SWEs are sparse. Additionally, it has been observed that the number of spherical waves needed to accurately compute interactions between multiple GS-matrix instances only forms a subpart of the number of spherical waves needed to accurately represent the fields radiated by a DUT in its near-field region. In combination with numerous additional optimizations, full-wave simulations run in the order of seconds on a simple home laptop. To further show the computational efficiency of the proposed simulation tool, support has been added for a cylindrical scan of a DUT by an antenna. This setup, often corresponding to more than one thousand full-wave simulations, only takes up about one minute on a simple laptop.
In using the developed simulation tool, we have encountered that in certain cases multiple reflections between DUTs can compromise its accuracy. However, deriving the scattering parameters for incident spherical waves is not straightforward due to the lack of support for spherical wave excitations in most full-wave simulation tools. Therefore, we have derived an alternative approach based on plane wave illuminations. An appropriate linear combination of plane wave illuminations allows us to mimic, to a sufficient degree of accuracy, arbitrary spherical wave excitations. We have validated this approach by comparing scattered field patterns for arbitrary incident plane waves to full-wave simulations. Subsequently, we have applied the scattering parameters for incident spherical waves in simulations where multiple reflections between DUTs play a significant role. Finally, the simulation tool is extended to support an infinite perfectly conducting plane underneath DUTs. Depending on the distance of the DUTs above this conducting plane, an approach based on mirroring fields sampled on a hemispherical surface or an alternative ‘image theory’ is applied. We have, however, encountered inaccuracies in the computations when image theory is applied. These inaccuracies are attributed to forward scattering of fields reflected by the conducting plane. Nevertheless, using the knowledge of the scattering parameters for incident spherical waves, the deviation due to forward scattering of the reflected fields is tackled in a straightforward manner, and we have subsequently observed a very good correspondence between the GS-matrix simulation tool and a full-wave simulation.
We have thus, in summary, developed a numerically stable and efficient circuit based topology that can be employed to study a wide range of system-level EMC problems. Several realistic applications are discussed to validate the proposed methodology.status: Publishe
Systeem-niveau hardware ontwerptechnieken voor EM Resilience: een noodzaak voor veilige en betrouwbare programmeerbare elektronica
No full textWith the advent of autonomous vehicles, Smart Cities, Industry 4.0 and many more Internet-of-Things related applications, our future society and lives become highly dependent on high-tech electronics. Unfortunately, all high-tech electronics are sensitive to ElectroMagnetic Interference (EMI), while the increasing electrification of, amongst others, vehicles and machines unavoidably means a much harsher electromagnetic environment. In addition, the continuing miniaturization of electronics and decreasing supply voltages makes new electronic products even more vulnerable to EMI. It is therefore of utmost importance to develop the required knowledge and techniques to assure that safety- or mission-critical systems will not suffer from unacceptable risks when being exposed to both intentional and unintentional EM disturbances. This challenge goes well beyond what is needed for compliance to the EMC Directive for CE certification for normal household applications. While for those applications, one malfunction in every 2-3 years might be perfectly acceptable, safety- or mission-related applications with possibly critical consequences might need a mean-time-between-failure of more than \SI{100}{} or even \SI{10000}{} years! For automotive applications, one even aims at only one dangerous failure in every 1 million years of operation due to the huge number of vehicles on the road.
The aim of the study leading to this PhD manuscript was to create techniques and measures to help achieve resilience to EM disturbances in safety- or mission-critical systems. 'Resilience' as used here means that in case of disturbance, the developed techniques and measures should make the system 'real-time fault-tolerant' for EMI so that the system continues to work as intended in a safe manner. In practice, the study for this PhD manuscript focused on hardware-based techniques and measures to minimize the Bit-Error-Rate (BER) within crucial communication channels. This was done by modifying some commonly used techniques from the discipline of Functional Safety, such as redundancy in combination with majority voting, with the appropriate EMC knowledge to make them much more performant to cope with EMI. Within Functional Safety, redundancy is mainly used to cope with random failures. However, EMI is a complex phenomenon which has to be seen as a systematic, common cause failure. Indeed, 'systematic' because a given system design in a given digital state will always behave in the same way when a given EM disturbance is applied. 'Common cause' because EMI influences many different components at the same time. A typical redundant system is to have two or more identical sets of hardware and software with the same inputs, and performing the same operations on them. When a malfunction occurs in one of these 'parallel channels', a comparator/voter detects that their outputs no longer agree and triggers appropriate actions to maintain safety. Unfortunately, the malfunctions that EMI creates in identical channels can easily be so similar that the comparator/voter cannot tell that there is a problem at all. In this PhD manuscript, several ways are presented to achieve that the parallel paths in a redundant system exhibit a different behaviour ('EM-diversity') when subjected to the same EMI.
To validate the performance of the proposed EM-diversity techniques, an efficient simulation framework is used. This simulation framework allows to apply a large variation of EMI disturbances (incoming fields, transient disturbances, ESD, etc.) to (simplified) models of safety-critical systems. The post-processing integrates statistical analysis to check how electromagnetic disturbances affect e.g. the BER. Thanks to this, the effectiveness of different types of diverse redundancy (inversion, spatial, frequency, time, etc.) for various types of EMI can be compared in depth.
The first part of this manuscript introduces two types of harsh Electromagnetic (EM) environments, namely a plane wave environment and reverberation environment. The first type can be compared with an open space environment in real life or an anechoic chamber as an EMC test environment. This type of environment subjects the system-under-test only to a single plane wave at a time. The second type of environment can be compared with a real life environment which has a lot of reflections occurring on e.g. as buildings, cars, humans, etc. In the EMC testing, this is mimicked in a reverberation chamber. This type of environment subjects the system-under-test to many plane waves, coming from many random directions, at the same time.
The experiments that have to be performed to analyse the EM-diversity properties of the proposed techniques and measures are incorporated in an in-house built simulation framework. This simulation framework is optimised for efficiency and applicability. The effect of the two EM environments is modelled by a limited set of full-wave simulations of the geometry under consideration. The results from that simulation are implemented in the framework and the effect of the disturbances is calculated by using an efficiently implemented reciprocity-based technique. In addition, all properties of the encoding and decoding methods for the data which is communicated over the subjected geometry can be modified efficiently. By using sets of random data and varying the parameters within the model using a Monte-Carlo method, statistically relevant metrics are achieved and can be used to compare the effectiveness of the introduced techniques and measures (T\&Ms) to create EM-resilience. The metrics comprises the BER and the number of false negatives or undetectable errors.
In this PhD manuscript, several new hardware EM-diverse T\&Ms are introduced. These T\&Ms are based on several properties of the hardware that can be changed. First, the possibility of matching or not matching the impedances of micro-strips is investigated on redundant and non-redundant geometries. Next, the use of an extra communication channel with inverted data is used to see if it could introduce EM-diverse behaviour. Furthermore, using three micro-strips in different orientations to create spatial diversity is investigated and effectively creates EM-diverse systems. Two final methods which change the timing of the data going over the communication channels is analysed. The transmission start time is changed to create time diversity and the transmission data rate is changed to create frequency diversity. Both methods show that they effectively introduce EM-diverse properties to the system, each with their own specific properties.
In addition, this manuscript studies the use of a matched filter as a possible measure to create EM-resilience. The matched filter is a well-known digital processing technique in receivers to maximise the signal-to-noise ratio. This technique was never before investigated in the light of EM-resilience. Additionally, the matched filter method is compared with a majority voter. It is shown that using a matched filter could even be more effective than using a majority voter under some condition.
The last part of this manuscript compares the proposed techniques in several ways and concludes which type of diversity to create EM resilience can be used in which situation. The comparison is based on the two main metrics used in this manuscript, namely the BER and the number of false-negatives or undetectable errors when using redundancy.status: Publishe
Replication Data for: Application of a Testing-to-Failure Approach to the Susceptibility Assessment of Electronic Systems
No full textThis dataset evaluates the proposed testing-to-failure approach under different electromagnetic environment. The trustworthiness and safety of an electronic system can be compromised by a harsh electromagnetic environment. Additionally, an electronic system may experience various types of failures under electromagnetic disturbances, resulting in varying levels of (un)reliable operation. To address this, this paper proposes the use of a testing-to-failure approach for characterising the susceptibility profiles of a medical monitoring system as an example. The approach is practically applied to the system under different modulated continuous wave electromagnetic disturbances, resulting in classified immunity test profiles indicating the severity of the occurring failures. These profiles are further analysed and compared among various types of disturbances.
The research results has received funding from the European Union’s EU Framework Programme for Research and Innovation Horizon 2020 under Grant Agreement No. 955.816. (MASCA-ITN ETERNITY)
Évaluation des risques électromagnétiques au niveau du système dus aux contraintes environnementales et au vieillissement : Application aux câbles blindés et aux connexions de masse des filtres CEM
No full textL’électronique automobile d’aujourd’hui évolue rapidement vers des solutions d’assistance à la conduite et de propulsion électrique. Pour industrialiser ces solutions, les problématiques de compatibilité électromagnétique (CEM) liées au vieillissement d’un équipement doivent être résolues. Cette thèse aborde deux points techniques clés : l’impédance de transfert des câbles blindés et la résistance de contact des connexions de masse des filtres CEM. Dans ce cadre, une méthode d’essai pour les tests de vieillissement hautement accélérés (HALT) a été développée dans le but de caractériser l’impédance de transfert et la résistance de contact. De ce fait, un ensemble représentatif de câbles blindés et de contacts de mise à la masse de circuits imprimés ont été caractérisés. Ainsi, il a été mis en évidence que les blindages avec tresse résistent mieux aux contraintes HALT que les blindages avec feuillard. Concernant les contacts de masse, des différences ont également pu être mises en évidence : les contacts à vis résistent à l’intégralité des contraintes HALT, les contacts sertis résistent aux contraintes HALT jusqu’à un niveau modéré de vibration, finalement, les contacts à ressort résistent aux contraintes thermiques, mais sont très sensibles aux vibrations.Today’s automotive electronics is developing rapidly towards more complex solutions for automated driving assistance and electric propulsion. To properly industrialize these solutions, the problematic of through-life electromagnetic compatibility (EMC) needs to be solved. This thesis discusses two technical domains of the problematic: transfer impedance of shielded cables and contact resistance of EMI-filter ground connections. A test setup for highly accelerated life tests (HALT) is developed for both transfer impedance and contact resistance characterisation. A representative set of shielded cables and circuit board ground contacts are then characterized. It is found out that braided shields withstand HALTstress better than foil shields in cables. For ground contacts, a clear distinction is also found: screw contacts withstand all the HALT stresses, swaged contacts withstand all the HALT stresses up to medium vibration level, and spring contacts withstand thermal stresses, but show great variation in vibration withstand
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