Projects

The widespread use of modern communication systems, the higher penetration of automated systems in automotive engineering, surgery, high-tech machines etc., the higher complexity present in those interconnected systems and the higher dependence of modern society on technology, creates an urgent need to recruit and train researchers in electromagnetic compatibility. This interconnected systems-ofsystems are creating a complex electromagnetic environment in which interoperability of the electrical and electronic equipment has to be achieved. A highly trained cadre of engineers is required to lead in this area and the aim of this initiative is to train such people, connecting them to the industry for implementation of the new acquired and developed knowledge and experience. The NEPIT consortium has been brought together not only to train qualified researchers but also to provide the fundamental research that underpins future technological developments. The multidisciplinary multinational doctoral training program will provide the trainee researchers with a complete broad experience and at the same time allows them to develop and eventually lead their focused area of research. The program will focus on the development of novel methods to model, simulate, design, evaluate and test complex systems for electromagnetic compatibility.
NEPIT will also develop corrective economic measures for safe, reliable, efficient and greener complex systems. Specific innovations expected to be achieved through NEPIT are methodologies to optimize the design, to reduce risks, and to improve the testing of complex high-tech systems. Dissemination methods to realize optimal impact will include scientific publications, presentations and workshops,
summer schools, training of engineers within industry as well as communication through newsletters, interviews, school visits, websites and social media.

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Development of methods to identify weak points in unmanned aircraft systems (UAS, unmanned aircraft systems, drones) with the aim of rendering them inoperable through adapted electromagnetic effects. The resulting scientific objectives are
- Measurement setup for determining an evaluable back-radiated signal in a smoky environment
- Fast methods for determining the drones' natural resonances
- Development of a database for classifying drones according to the measurement results obtained and recording the electromagnetic (EM) weak points of drones
- Development of methods and equipment for the generation of adapted high-energy EM interference
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Development of procedures to ensure the electromagnetic compatibility (EMC) of vehicles with Advanced Driver Assistance Systems (ADAS) with the scientific sub-goals:
- Development of test strategies for the EMC test of vehicles with ADAS systems
- Provision of an EMC-capable radar target generator for measurements in EMC absorber halls
- Proof of the feasibility of a LIDAR (Light Detection and Ranging) target generator for EMC vehicle measurements and construction of a prototype
- Creation of the basis for a comprehensive EMC test of vehicles with activated ADAS systems as a vehicle in the loop (ViL) test
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Ultra-high field magnetic resonance imaging is an advanced medical imaging technology and plays an important role in the study of brain function and neurobiology. It enables scientists to capture detailed images of the brain and track functional activity in real time. This can contribute to a better understanding of brain diseases, cognitive processes and neurological disorders. The technical goal of this project is to realize a universal integrated console for high-field MRI systems. The MRI console developed in this project surpasses all systems available commercially or as home-built systems to date and will enable OVGU and thus the state of Saxony-Anhalt to expand and secure its flagship activities in the field of MRI and neurosciences in the coming years. Furthermore, the project offers an excellent opportunity for integration into the
high-tech strategy of the state of Saxony-Anhalt with the establishment of semiconductor technology and microelectronics companies. With UIC4UHFMRI, the toolchain from design to system integration of modern semiconductor components is being established at OVGU.
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As part of the project, the horizontal integration of several autonomously operating active filters based on a real-time capable fieldbus network and their vertical integration into a superimposed network management system are to be realized.
The active filters (APF-ActivePowerFilter) are designed to work with an innovative network impedance measurement method (invasive method). The real-time data of the distributed active filters is stored in an APF host PC, which is also the communication master for the real-time-capable filter network. Vertical integration into the supply network and connection to the network management system takes place via a gateway functionality implemented in the APF host PC.
This planned active network management system is intended to create a component for holistically safeguarding the network quality of industrial networks.
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Unmanned aerial vehicles (drones) were reserved for the military for a long time. The drop in prices and the increasing technical possibilities of electronics and sensor technology have led to a large number of civilian available electric motor-driven drones, whose areas of application range \ua from photography and video recording to search and rescue operations and cargo delivery. With this growth, incidents at critical infrastructures such as airports are increasing sharply. The number of incidents has

In response, several countries have enacted new regulations for civil airspace. However, this does not reduce the risk of criminal or terrorist use. There are currently no reliable concepts for civilian defense against these drones. Current protection concepts include interceptor drones with nets, projectiles or trained birds of prey. There are also systems on the market for defense systems that are based on electromagnetic radiation. The radio link between the drone and the base station is disrupted by broadband interference signals, forcing the drone to land in most cases. Comprehensive studies on the mechanisms of action of electromagnetic radiation on civilian drones do not yet exist.

For this reason, the aim of the study is to demonstrate the possibilities of efficiently disrupting or destroying drones through the use of electromagnetic sources. The first step is to use commercially available drones to carry out metrological investigations into interference immunity in order to determine critical frequencies and field strengths at which the functionality of the drones is restricted. This data will be used to identify interference mechanisms and investigate electromagnetic coupling paths in more detail.
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A new method for describing the scattering of electromagnetic waves on straight, thin conductors and slit-shaped apertures is to be generalized,
thin conductors and slit-shaped apertures is to be generalized in order to analytically describe the scattering processes on arbitrarily shaped one-dimensional structures. For this purpose, the overall problem is broken down into a part of the near and far interaction of the sources and fields using the method of analytical regularization in order to subsequently find analytical solutions using the characteristic properties of the parts.
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A classic focus of electromagnetic compatibility is the protection of radio communication services from unwanted interference emissions. To ensure protection, electrical devices must comply with standardized limit values.
With the introduction of 5G services, several new radio services have been established well above 6 GHz. In order to cover this frequency range, the previous measurement methods for frequencies up to 6 GHz have been transferred to a frequency range up to 40 GHz. As the electrical size of the device under test increases at high frequencies and correspondingly small wavelengths, the complexity of the radiation pattern increases. Determining the maximum emission using established methods proves to be difficult due to the thermal noise of the devices, the attenuation of the signals by cables and the high directivity of the DUTs. A higher antenna gain initially helps to improve the dynamic range, but at the same time reduces the probability of detecting the highest emission and therefore significantly increases the measurement effort. As an alternative measurement environment, the measurement effort can be reduced in a mode swirl chamber, as the mode swirl chamber's mode of operation allows the total radiated power to be recorded without rotating the DUT or tilting the antenna. The aim of this study is to investigate different measurement methods in terms of reproducibility and practical effort.
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The main objective of the research project is the analytical investigation of the currents on twisted pair cables in the frequency domain in order to improve the understanding of the electromagnetic behavior of these cables. For this purpose, an asymptotic approach and an iterative method, which were developed for uniform wires, are extended for twisted wires. In this way, high-frequency effects are taken into account in the analytical solution. The results are used, among other things, to compare the complex resonant frequencies of twisted pairs with those of equivalent uniform pairs.
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The research project is supposed to make a contribution for assurance of the quality of supply in industry networks and functional building considering the integration of renewables energies. For this purpose a system of intelligent distributed active filters is planned and implemented as demonstrator, to reduce the harmonic level in low voltage networks.
The system will consist of several compact filter units which can be installed at various points within a low voltage switchboards. The single filter units share the task of harmonic reduction. The objective is, to achieve this without communication between the units. The respective active power will be in proportion to the nominal power of each single filter. Focus is also to avoid instability effects, e.g. caused by resonances.
Inter alia, the use of silicon carbide semiconductors will be innovative. In addition to harmonic compensation further criteria for improvement of power quality such as reduction of unbalances as well as flicker and power factor correction will be considered.
In comparison to a single filter with high nominal power a reduction of harmonic level in public and industry low voltage networks with improved cost efficiency will be achieved. The modular size of the single units in comparison to the present solutions will cause an improvement of energy efficiency combined with flexible use. The overall system is characterised by simple operability and high functionality.

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The project aims to develop and construct a measurement adapter with which the dielectric properties of sound samples, in particular their complex-value permittivity and the loss angle, can be investigated more precisely in the frequency range up to several gigahertz. For this purpose, a coaxial arrangement is to be designed that enables a two-port scattering parameter measurement with a vector network analyzer. When empty, the coaxial arrangement should have a characteristic impedance of around 50 ohms, which is common in high-frequency measurement technology. The change in the measured reflection and transmission coefficients of the arrangement filled with sound samples is then used to draw conclusions about the properties of the samples.
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Resonant inductive charging systems or wireless power transfer systems (WPT systems) are used for charging mobile systems such as autonomous robots. A decisive factor for the expected interference emissions with regard to the electromagnetic compatibility of such WPT systems is the exact positioning of the robot above the charging coil. As part of the research project, the influence of the positioning accuracy of autonomously moving robots with WPT charging technologies on the electromagnetic interference emissions was investigated and evaluated with regard to the requirements of the applicable EMC standards.
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RFID tunnels are used for the wireless tracking of parcels and goods along transport routes and in warehouses and logistics centers. It is a very cost-effective method in which the tags are supplied with an electromagnetic field during the readout process so that the tags do not require their own battery. The tunnel is electromagnetically shielded for more reliable RFID reading. Various methods for measuring the shielding attenuation of an existing RFID tunnel were tested in the research project. For this purpose, the concept of nested electromagnetic mode swirl chambers was used, as it offers a statistically homogeneous and isotropic field, a high dynamic range and thus a reliable and efficient measurement method.
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Within this project, it is planned to investigate the coupling of statistical fields into line structures in the time domain for the first time. Both two- and three-dimensional line structures will be examined theoretically and experimentally. Non-linear line terminations and the associated effects such as a temporal change in the reflection parameters, demodulation of high-frequency carriers and intermodulation of different frequency components will also be addressed. Experimental proof of each theory is provided by measurements in a GTEM cell for a plane wave as well as in a mode swirl chamber for a stochastic field.
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In order to analyze the possible improvement of field homogeneity and isotropy by two additional copper hemispheres mounted on the wall and floor of a reverberation chamber (see Fig.), the electric field strength has been measured at eight positions in the working volume of the chamber. The measurement has been carried out over wide frequency range using fast field sensors. The experimental results are analyzed in terms of the standard validation procedure for an empty reverberation chamber according to Annex B of the IEC 61000-4-21 as well as to the field anisotropy coefficients defined in Annex J of this standard. The results show that the copper hemispheres hardly improve the field uniformity and slightly lower the quality factor of the chamber.

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The reflection coefficient of cable terminations plays a major role in many practical applications. As a rule, attempts are made to avoid reflections during signal transmission in order to keep interference to a minimum.

Classical line theory provides a known expression for the reflection coefficient as a function of the terminating impedance and the characteristic impedance of the line. However, classical conduction theory only considers transverse electromagnetic (TEM) modes. This limitation is legitimate for low frequencies or long wavelengths compared to the transverse dimensions of the line and provides accurate results. However, data rates and signal frequencies are increasing in many application areas and other solution methods are required.

Easy-to-use numerical solvers provide numerical values for any line geometry that can be interpreted. However, one rarely gains a deeper insight into the physical processes taking place in the background. For this reason, an analytical, iterative method has been developed in the past that extends the classical line theory for higher frequencies. The method provides relatively accurate results and contains information about the higher modes (in addition to the "TEM" mode). The line geometry at the port is also included in the solution.

From a theoretical point of view, the classification of the new iterative method is interesting. The question that arises is: Is the iterative method unique or can the same results be found with other known methods? In this project it was shown that the relatively well-known induced "EMF" method provides the same analytical result for the reflection coefficient. As an intermediate result, the reflection coefficient was linked to the input impedance in general.
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One of the main problems in electromagnetic compatibility is an analysis of electromagnetic field coupling with wiring structures, which have a number of applications. To solve this problem usually direct numerical methods are used, e.g. the method of moments. However, these methods do not allow deep research into the physical essence of the problem under consideration. This can only be achieved by using analytical or semi-analytical methods. The exact analytical solutions that are possible for structures with high symmetry are important: an infinite straight wire, a circular wire, a helix wire and their combinations that keep symmetry, for example, an infinite straight wire over an PEC surface. Here, we consider a circular half-loop perpendicular to the PEC ground. This structure is the only finite wiring structure for which there is an exact solution to the mixed-potential integral equations. This solution can be obtained by Fourier series for any type of excitations, including distributed excitations (e.g. by an external plane wave) or lumped excitations (e.g. by a voltage source). The solution for the lumped excitation is especially important because it is a Green's function for the current and yields the solution for a loaded wire.
To obtain this solution with appropriate accuracy, one has to use 100 to 400 terms in the Fourier series. In our previous paper, we have shown, how to simplify this Fourier solution and, using the phenomenological physical method, approximately obtained the main term of the current excited by lumped source. This current is analog of TEM mode excited by a lumped source in the infinite straight wire above a PEC ground. In this work we use the Watson-Regge transformation and represent the Fourier sum as an integral in the complex plane of the parameter m, which is an integer in the classical Fourier solution. The integral is defined by the zeros of the modal impedance per-unit length in the complex plane of the parameter m, which zeros define the so called Regge poles, in analogue with scattering theory in quantum mechanics. The positions of the poles on the complex plane depend on the frequency and form so called Regge trajectories. The sum over the Regge poles is an exact solution of the problem and equals the sum of Fourier series. The term corresponding to the pole with the smallest imaginary part coincides with the phenomenological solution. Moreover, after some manipulation on this term, one can obtain the SEM poles of the first layer for the wiring structure.

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The eMobility Competence Center project addresses the structural challenges and develops solutions in key areas as part of a newly established competence center, which will significantly strengthen cooperation between SMEs and university research and teaching. The knowledge can be transferred directly to the affected supplier industry, where it can help to successfully manage structural change and exploit new economic opportunities. In addition to the primary objective of building up and transferring core know-how, the main focus is on the long-term anchoring of the knowledge gained in economic structures that create jobs.
In the AUTONOMOUS DRIVING research area, the initial foundations are being laid for the development of a test environment for autonomous vehicles. The long-term goal is to demonstrate the functionality of the entire vehicle as hardware in the loop. The necessary skills in the field of testing and inspection of autonomous driving components and systems are being developed. This represents an important first step towards establishing and developing expertise in autonomous driving itself and is initially closely focused on the topic of testing and inspection, which is being worked on jointly in terms of methodology and testing technology.
In the sub-project "Test environment for automated and autonomous electric vehicles" supported by the Faculty of Electrical Engineering and Information Technology (Chair of Measurement Technology and Chair of Electromagnetic Compatibility), fundamental considerations on the use of a radar target simulation for automotive applications are being carried out. Head of the Competence Center eMobility Research Area Autonomous Driving: Prof. Dr.-Ing. Ralf Vick.
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- different cell types can be used
- Optimization potential for the electric drive train

• consistent consideration of electromagnetic compatibility

Different numerical methods (MoM, FDTD, etc.) can be used to calculate currents and voltages induced in wiring systems by external EM fields, but they are not very helpful to gain insight into the physics of coupling phenomena, especially in time domain. In contrast, the analytical singularity expansion method (SEM) represents the scattering objects as a set of oscillators, thus giving a physically transparent tool for the description of the coupling phenomena, both in frequency and time domain. The set of SEM poles yields the main contribution for the response function (functional) of the transmission line to the excitation. It also defines the scattering amplitude, response in the time domain, etc. Studies of SEM poles were carried out earlier by analyzing the results of numerical calculations using the Method of Moments (NEC), or using approximate analytical methods for long horizontal wires above ground. Recently, we have proposed to use the previously developed method of modal parameters (MoMP) for the analysis of poles in short-circuited wire structures of arbitrary geometric shape.
In this work, we apply the method of modal parameters for investigation of SEM poles of open-circuit wires. The main accent is done for investigations of pieces of symmetrical wire structures: a straight finite wire in free space, a straight finite wire parallel to a PEC ground, a circle arc and a helix segment. The symmetry of these structures allows a fast calculation of matrix elements in the MoMP, especially for the straight wire where one can obtain explicit analytical result and investigate poles of high layers. The investigation has shown that the real part of the SEM poles for a finite straight wire in free space, a finite straight wire above a ground plane and a circular arc wire increases monotonically with increasing the number of the pole. In contrast, for a large segment of the helix wire, a more complex dependence of the real part of the SEM pole on its number n is observed. This is due to the fact that for some numbers n of the pole there are effective common modes of the current, which corresponds to strong radiation and a large real part of the SEM poles, and for some $n$ there are effective differential modes, which corresponds to weak radiation and a small real part of the SEM poles.

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Shielded cables are used in many electrical systems to protect the inner conductor from conducted and field-bound interference. Braided shields offer greater flexibility in cable routing than continuous metal cylinders and are therefore used more frequently. Through the openings in the shielding resulting from the braiding, fields can penetrate to the inner conductor and disturb the system. These coupling mechanisms can only be investigated to a very limited extent in network simulation programs, as their libraries do not yet include models of shielded cables above a ground plane. This significantly restricts the EMC analysis of shielded systems.

In this work, network models for shielded cables were designed based on line theory, which take into account the coupling between the outer and inner areas of the shield and vice versa. This makes them suitable for network-based system analysis. The designed networks can calculate the induced voltages due to incident plane waves and perform a conducted EMC analysis in the frequency and time domain. The models can represent both single coaxial cables and shielded multiple conductors.

A simulation example for a shielded cable with consideration of field coupling is shown in . A pulsed plane wave with the angle of incidence theta and the electric field E irradiates the cable. The induced interference voltage of the internal system is shown. Validation is carried out by comparing the results with the CST simulation software.
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The coupling of external electromagnetic fields into supply, connection and communication cables significantly determines the radiated immunity of the systems and assemblies connected to them. Cable harnesses can be modeled as cable networks on which current and voltage waves excited by field coupling propagate along the individual cables and are transmitted or reflected at nodes and terminations.

Line ends are often terminated with non-linear semiconductor components, e.g. as overvoltage protection. Their consideration requires a simulation in the time domain. The lines, which are assumed to be low-loss, can be modeled as a chain of L-C links. According to the Agrawal formulation, the incident field of a plane wave is effective as distributed voltage sources along the line and as concentrated voltage sources at the line ends.
In the transient simulation, these sources at the nth position of the mth line and other sources at the top termination or node of the network must be subjected to the time function of the field, which is scaled and shifted in time depending on the direction of incidence and polarization. For this purpose, the sources can be calculated very easily in numerical software such as MATLAB and used directly in a network simulator, also programmed in MATLAB, based on the modified node voltage analysis to simulate the line equivalent circuit diagram. The disadvantage here is the complex implementation of non-linear loads. An ideal diode according to the Shockley equation can still be taken into account relatively easily. However, more practical diode and transistor models, which contain more semiconductor-physical properties, are significantly more complex to implement.

The idea developed in this project is to use existing SPICE-based network simulators for the transient simulation of field coupling in a line network. The corresponding network lists with the numerous different voltage sources are generated automatically from MATLAB using the simulation parameters. The advantage of this is the ability to use the large number of existing semiconductor component libraries, some of which are proprietary, and the possibility of automatic time step selection to improve the efficiency and convergence of the numerical solution.

In the project, a numerical simulation method for the transient field coupling of pulsed plane waves in line networks with non-linear terminations was developed for the first time, which is based on standard SPICE-compatible network simulators. Compared to similar existing methods, many more semiconductor device models can be used. Furthermore, the efficiency and numerical stability of the simulation method is increased.
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The present project for the gradient system component is a project covering the innovative components of a neonatal MRI system. It serves the pre-development of a gradient system for diagnostic MR imaging at 1.5T, including devices for active interference suppression to ensure bilateral electromagnetic compatibility.
This project is also about building up know-how in the field of gradient systems. This know-how can enable the project partners to manufacture the expensive gradient coil component locally in Magdeburg after completion of the project and reduce the risk of possible dependence on the few commercial suppliers.
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Background
Real-time monitoring for radiofrequency ablation (RFA) is required to obtain information about the complete destruction of cancerous tissue. However, no RFA system exists that allows real-time MR monitoring. The MRI Hybrid Ablation system is an innovative system, where the MR scanner itself is used as a power source for RFA.

Objective
It was supposed to investigate whether it was possible to monitor a RFA procedure using the concept of an MRI hybrid ablation system.

Methods
By connecting an electrode to the coil port of the MR device, access to the RF infrastructure of the MRI can be required. Hereby, the electrode will be used for thermal destruction of tissue as well as for MR imaging. Electromagnetic and thermal field simulations were performed to numerically evaluate these possibilities. The simulations were validated while performing ablation experiments with protein phantoms and ex-vivo tissue in a MR environment. Here, the heat-based experiments were accompanied by acquisistions of temperature and flip angle maps.

Results
The thermally destroyed tissue correlates with the predictions from MR thermometry as well as the numerically calculated heat depositions. The flip angle maps als show a correlation with respect to the simulated MR signal distribution.

Conclusions
Using the concept of an MRI hybrid ablation system it is possible to perfom a thermal procedure and to monitor the RFA with MR thermometry. The approach of monitoring the ablation process by flip angle mapping is strongly compromised by long measurement times.

Originality
An approach has been developed to use the MR scanner as an "MR-compatible" therapeutic device. To date, no comparable, commercially available clinical RFA system exists that allows to monitor RFA with MR thermometry.

Keywords
MRI, radiofrequency ablation (RFA), thermometry, monitoring, hybrid system

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As part of the study, options for setting emission limits for frequencies above 1 GHz were developed. The relevant parameters for integration into the IEC database were derived from the technical specifications of the telecommunications standards organization 3GPP. The limitations of the original CISPR TR 16-4-4 procedure for applications above 1GHz were identified. Nevertheless, limit values for the electric field strength were derived from the CISPR method with corrected parameters. Since the relevant parameters for the description of mobile radio services are primarily specified in power values, a method based on power values was also introduced and initial tests were carried out on its applicability in the mode swirl chamber.
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As part of the study, options for setting emission limits for frequencies above 1 GHz were developed. The relevant parameters for integration into the IEC database were derived from the technical specifications of the telecommunications standards organization 3GPP. The limitations of the original CISPR TR 16-4-4 procedure for applications above 1GHz were identified. Nevertheless, limit values for the electric field strength were derived from the CISPR method with corrected parameters. Since the relevant parameters for the description of mobile radio services are primarily specified in power values, a method based on power values was also introduced and initial tests were carried out on its applicability in the mode swirl chamber.
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Receiving coils are an important component of every magnetic resonance tomograph, as they have a decisive influence on image quality. For diagnostic use, there is already a wide range of available concepts whose properties have been specially optimized for this purpose. However, these are usually difficult or impossible to apply to the conditions of an interventional setup. Special requirements for use during an image-guided surgical procedure are sterility and good handling of the coil, i.e. the interventionalist should be hindered as little as possible. Problems here are, for example, coil openings and cable guides that are too small in existing concepts. The aim of the research project is to develop a concept that meets the requirements in a simple way, but still impairs the reception properties of the coil as little as possible.
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Cables are indispensable for transmitting information and energy. However, they also couple external
electromagnetic (EM) fields into devices, which can destroy electronic circuits, for example. Therefore, the analytical investigation of line coupling is of great importance for a better understanding of the physical phenomena and for the extension of mathematical methods. The Singularity
Expansion Method (SEM) is an intuitive method for visualizing the induced current on any electrically conductive object. Motivated by experimental results, the current in the time domain is represented by a sum of weighted, damped sinusoidal signals. Laplace transformation
results in a sum of weighted pole positions in the frequency domain. The complex pole positions are generally also called natural frequencies. The natural frequencies determine the position of the magnitude maxima of the frequency response. In the time domain, their imaginary part indicates the frequency of the sinusoidal
It is noteworthy that these frequencies are independent of the excitation (EM field, current source, etc.). Therefore, an analysis of the natural frequencies is crucial for a deeper understanding of the conduction coupling mechanisms. The first aim of this project is the further development of three different analytical methods to determine the
natural frequencies of thin line structures in the frequency domain: - an asymptotic approach, - the modal parameter method, - the line super theory. The asymptotic approach is a physical approach which is to be extended by further physical considerations in order to better understand the coupling mechanism.
better understand the coupling mechanism. The method of modal parameters illuminates the problem from a
from a functional analytical point of view and has the advantage that it can be used to calculate the natural frequencies in all layers with high accuracy. Thirdly, the calculation of the natural
natural frequencies from the point of view of line super theory. This theory has been developed at the applicant's institute over many years and is now to be further analyzed from the point of view of the SEM. The second objective is the qualitative investigation of the trajectories of natural frequencies in the complex plane when varying the dimension and terminations of simple line structures. This should increase our understanding of the significance of natural frequencies. In addition, first experiments for the identification of different simple line structures will be carried out. The analytical results will be compared with numerical simulations and simple measurements for validation.
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A high efficiency of electric vehicles requires an optimum compatibility of all components of the electric

drive system. Solutions for dynamic energy buffers, energy-efficient drive control and their integration into a
system are not yet a state of the art. The energy efficiency of hybrid and electric vehicles can drastically be
raised by new dynamic energy buffers. The use of higher clock frequencies and improved control strategies
of the inverter, coupled with an improved motor design (which reduces the coupling between inverter,
engine and vehicle) offers a potential for improving efficiency, reliability and life time combined with reduced
EMC measures and weight and volume reduction. The modeling and simulation methods for electric and
hybrid vehicles on system level have to be further developed for a reduction of future development times.
All these problems should be solved within the project.

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In modern vehicles, electrical drives lead to electromagnetic interference due to the rapid switching of power electronic actuators. These can couple over to neighboring electronic components and cause malfunctions. Ensuring reliable functioning requires a system analysis that today is only possible using complex simulations. In the project, substitute models for electrical machines are being developed that make it possible to simulate their behavior in the system.
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The research project serves to investigate the coupling of statistical electromagnetic fields with a narrow-band spectrum into electrical and electronic assemblies, devices and systems. Such fields occur in the context of electromagnetic compatibility in electromagnetic mode swirl chambers (an alternative measurement environment for radiated immunity and emission tests) and in electrically large and geometrically complex cavity resonators (such as ships, aircraft fuselages, vehicle bodies, satellite housings and industrial environments with large metallic structures). During the project, existing models for statistical fields and already developed analytical and analytical-numerical calculation methods for the coupling of such fields into simple systems (e.g. electrical connection lines) will be applied together with newly developed simulation methods for analyzing the coupling. Selected simulation results will be compared with experimental data from measurements in mode turbulence chambers. The knowledge to be gained in the project can contribute to the establishment of more efficient and more precise measurement methods for electromagnetic compatibility.
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The analysis of transmission lines with random geometry in a resonator requires time-consuming numerical solutions to calculate the statistical properties of voltages and currents along the line and at the terminal. Moreover, the calculations of the response of deterministic transmission lines inside a resonator as well as the response of stochastic transmission lines in free space are also very tedious. During the usual numerical simulation it is often difficult to explain the differences between results of different configurations. These can be either caused by peculiarities of the used model or are of a deeper physical nature. A consequent and accurate analysis of the situation can only be done by using analytical methods. In a previous project a model-independent theory of transmission lines with stochastic geometry was developed. Furthermore, effective analytical and semi-analytical methods for the fast analysis of the response of deterministic transmission lines in resonators were developed. In this project further developments of the methods are intended with the aim to carry out the investigation of stochastic lines in a resonator. It is planed to study the statistical properties of the scattering matrix (reflection and transmission coefficients) of transmission lines, the current distribution in the central region of the line and the response of the line to the external electromagnetic interferences by use of analytical methods.

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The number of operating resources that have an unfavorable effect on power quality is constantly increasing. The demand for greater energy efficiency while maintaining or even improving supply reliability is also growing. The current development from centralized energy supply to smart grids requires new approaches. Predicting the expected effects requires mathematical models that are able to reflect the interactions between the operating resources. As the composition of the electrical supply system continues to change, potential threats to power quality and electromagnetic compatibility (EMC) can be identified and countermeasures can be tested for their effectiveness in a cost-efficient manner using simulation. Reproducible measurements form the basis for the development of suitable models. The project comprises the design, acquisition, installation and commissioning of a test rig consisting of a high-performance grid simulator, a PV simulator, various electronic loads and adequate measuring equipment. The system will be fully integrated into existing laboratory halls. Together with existing laboratory equipment, this will enable a comprehensive analysis of non-linear equipment and generators in terms of voltage quality and EMC as part of future scientific and industrial research.
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The testing/diagnosis and monitoring of power cables is of particular importance. The instruments and systems currently available on the market are inadequate, so there is an enormous need for development in order to be able to serve the emerging (global) market. The project helps to close the gap between growing demand and technology supply and paves the way for a cost-efficient online monitoring of cables and terminations as a spin-off. The research project aims to develop algorithms for automatic fault location in branched energy supply networks and to research methods and technologies for a sensor system and evaluation unit for online/offline measurement of important cable quality criteria.
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The research project developed an efficient calculation scheme for the transient coupling of plane waves into uniform lines. The method is based on closed equations that are evaluated in the form of a finite sum. The method can be used for single lines above a conductive plane as well as for double lines in free space. The lines can be terminated with any number of terminating resistors. The incident plane wave can be described by any time function whose master function exists. Compared with a calculation in the frequency domain and subsequent inverse Fourier transformation, the method developed is much faster, numerically more accurate and very easy to understand.
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Theoretical considerations of cables are generally based on the assumption of thin-wire arrangements, for which there are already many known and published scientific findings. However, in practice, e.g. in electric vehicles, energy systems and overhead lines, bulk conductors (thick conductors) are used for the most part. However, it is not possible to transfer the description of thin-wire arrangements to bulk conductors, so there are only a few specific scientifically substantiated statements for bulk conductors. Knowledge of the electromagnetic properties and behavior of bulk conductors with regard to their electromagnetic compatibility is an important prerequisite for the optimal economic use of cables in practice.
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The development of new devices and instruments for interventional magnetic resonance imaging places special demands on product design. In particular, care must be taken to ensure that no ferromagnetic materials are used, that extremely high interference levels can occur in the vicinity of the tomograph, that the tomograph itself is sensitive to interference and that all systems can interact strongly with the human body. For the last point in particular, it is important to be able to accurately estimate the heating of the human body during the procedure and to know what influence various instruments or materials have. Simulations are currently the only way to provide reliable information on this, which is why various program packages have been established for this task in recent years. The Chair of Electromagnetic Compatibility therefore tested an alternative approach by using only freely available program packages and models for the calculations. The aim was to show that even such a complex problem can be solved by cleverly combining various tools. Such an open source solution offers the following advantages: free availability of the source code, no license fees and high flexibility, but also requires the user to have a high level of understanding of the individual work steps.
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The influence of openings in conductive walls of cavity resonators on the internal field distribution is crucial for understanding the shielding effectiveness of an enclosure. Current work describes the coupling of an external electromagnetic field with the internal field caused by the aperture. Cavity modes excited in this way can excite further apertures, especially in the high-energy resonance case, and thus contribute to the external scattered spectrum. Using a cuboidal cavity resonator with several apertures, this work is dedicated to the question of the extent to which a statement can be made about the interaction between the cavity modes and the scattered field of the resonator using analytical models. For this purpose, an analytical expression for the field distribution inside the resonator is used in a first step.
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At the Chair of Electromagnetic Compatibility, a theory for coupling statistical fields into a cable has been developed and presented in several publications. This theory has already been validated by measurements on single lines above a conductive plane and was to be confirmed by further experiments with a straight and uniform double line. For this purpose, a corresponding measurement setup was set up in the large mode-vortex chamber at Otto von Guericke University in Magdeburg.
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The fast switching power electronics devices which used in a switching mode power supply (SMPS) applications generate undesired currents through stray capacitors which may cause conducted electromagnetic interferences (EMI). So that the prediction of the conducted emission noise (common moded (CM) and differential mode (DM)) especially at resonance cases of SMPS is important before prototyping. The goal of this project is design an appropriate model of the SMPS which considers various frequency-dependent effects. In addition to that the model has to describe the paths of the CM and DM currents in the frequency domain.

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Various measurement methods exist for determining the radiated interference emission of test specimens, which record different measured variables. These measured quantities cannot always be converted directly into each other and must be related to the reference quantity, the electric field strength in free space. The aim of the project is to investigate the methods, in particular with regard to the uncertainties in determining the interference emission of electrically large test specimens, and to specify possibilities for the mutual conversion of the results.
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The project investigates the coupling of electromagnetic fields with lines of arbitrary, stochastically described geometry. Several examples of such problems can be cited in the context of electromagnetic compatibility: - Determination of the currents and voltages induced by external electromagnetic fields in multiple lines or communication devices and their statistical distributions. - Investigation of the statistical properties of the mutual coupling between line segments to ensure the internal EMC of a system. In the project, already developed analytical and analytical-numerical methods are to be applied together with new mathematical methods of physics (diagram technique and the theory of equations with stochastic parameters) to analyze the properties of lines.
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Increasing demands on the controllability and conversion of electrical energy are increasing the use of power electronic equipment in electrical supply networks. This development requires increased attention to the voltage quality in the grid, as consumers connected to the grid via power electronic circuits are the cause of line-bound interference. The harmonic currents propagate in the grid, can interfere and lead to undesirable voltage drops at the grid impedances. Ensuring the quality of supply in the long term requires the simulation and prediction of the behavior of harmonic currents using mathematical models. Conventional methods of harmonic analysis such as the constant current source model or the Norton model are no longer sufficient to simulate the interaction phenomena between the different harmonic orders. In the project Modeling of nonlinear loads for the investigation of harmonic phenomena, alternatives are therefore being developed. The focus is on the approach of a voltage-dependent current source. The modeling is carried out in the frequency domain. The non-linear load is modeled as an admittance matrix to describe the dependency between the vector of currents and the vector of voltages.
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The use of power electronic circuits is necessary for the operation of electrical appliances. These circuits cause electromagnetic interference. Interference can be reduced with the help of filters. The resulting conducted types of interference can be attenuated using filter circuits. In order to represent the behavior of a filter circuit without measurement, the impedance of the circuit can be simulated using empirically determined equivalent circuit diagrams of the individual components. In EMC, it is important to know the propagation characteristics of the conducted interference and the frequency behavior of the individual components in order to select the correct components and filters. A method has been developed that makes it possible to determine the equivalent parameters of the individual components and the resulting impedance of a filter circuit without time-consuming measurements.
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The design of filters for auxiliary units on the high-voltage grid is examined, taking into account the influence of the load current on the filter properties (saturation, surge stresses). Filters using conventional technology are examined and analyzed to determine how the typical 70/40 dB attenuation curve can be achieved under low-cost aspects. The necessary simulation models are created and the properties of the constructed filter are verified using various measurement methods.
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Electrical cables are often the main entry points for electromagnetic fields into a test object. A theory for the description of the coupling of statistical electromagnetic fields, such as those occurring in mode swirl chambers or in other electrically large and geometrically complex cavity resonators such as aircraft fuselages and satellite housings, was developed at the Chair of EMC. The aim of this research project was to validate the existing theory through measurements.
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Modenverwirbelungskammern werden zunehmend als alternative Testumgebungen für gestrahlte Störfestigkeitsuntersuchungen innerhalb der elektromagnetischen Verträglichkeit diskutiert. Entscheidend für die erfolgreiche weitere Anwendung ist ein tieferes Verständnis der Einkoppelmechanismen des statistisch homogenen und isotropen Feldes in komplexe Systeme. Da Leitungsstrukturen häufig einige wichtige Einkoppelstelle darstellen, sollen in einem ersten Schritt Einkoppelphänomene von stochastischen Feldern in einfache Leitungsstrukturen untersucht werden. In einem zweiten Schritt soll die Theorie auf ungleichförmige Mehrfachleitungen zur Betrachtung der Einkopplung in komplexe Systeme erweitert werden. Alle analytischen und numerischen Ergebnisse sollen mit experimentellen Daten validiert werden.

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Zur Bestimmung der gestrahlten Störaussendung von Prüflingen existieren verschiedene Messverfahren, welche unterschiedliche Messgrößen erfassen. Diese Messgrößen sind nicht immer direkt ineinander umrechenbar. Ziel des Projektes ist es, die Verfahren insbesondere hinsichtlich der Unsicherheiten bei der Bestimmung der Störemission elektrisch großer Prüflinge und den Bezug zur Referenzgröße hin zu untersuchen und Möglichkeiten zur Umrechnung der Ergebnisse ineinander anzugeben.

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The possibility of using modern electromagnetic field calculation methods to optimize RF heating processes is being investigated. For this purpose, usable models are to be developed and an assessment of their usefulness for calculating dielectric losses and the temperature distribution is to be carried out.
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Es werden die Grundlagen zur Entwicklung eines leistungs­fähigen, modularen und effizienten Prüf- und Fehlerortungssystems für Seekabel und Energie­kabel großer Länge, wie sie z.B. für den Einsatz bei Offshore-Windparks mit HGÜ benötigt werden, entwickelt. Dabei  steht die Entwicklung von Modellen zur Simulation der elektromagnetischen Verkopplung im Prüfsystem und die theoretische Beschreibung der Ausbreitungsvorgänge von Mess- und Störsignalen unter Berücksichtigung der Mehrfachreflexionen in vermaschten Kabelnetzen im Focus des Projektes.

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Bei der kontaktlosen Energieübertragung wird über einen Luftspalt induktiv Energie übertragen. Die Speisung des Spulensystems erfolgt in der Regel über einen Wechselrichter. Aufgrund der Schaltvorgänge können elektromagnetische Störaussendungen entstehen. Ziel ist es, diese Emissionen durch geeignete Modelle zu bestimmen

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In Hybridfahrzeugen werden Komponenten eingesetzt, die sowohl am Hochvoltnetz als auch am Bordnetz betrieben werden. Damit besteht die Gefahr einer Verkopplung zwischen stark störenden und empfindlichen Komponenten. Ziel des Projektes ist die Analyse und messtechnische Bestimmung des Übersprechens der Systeme in unterschiedlichen Komponenten.

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Im Projekt sind Simulationsmodelle zur Berechnung der auf Versorgungsleitungen resultierenden Impulse beim Ein- und Abschalten von induktiven Verbrauchern (Kleinmotoren, Motoren mit Fremderregung, elektromechanische Ventile) zu erstellen, deren Gültigkeit zu verifizieren. Dabei ist insbesondere die feststellbare Bandbreite realer Messergebnisse in der Simulation zu berücksichtigen, d.h. die Modelle sind parametrisierbar zu gestalten, so dass eine statistische Aussage über die auftretenden Spannungsamplituden möglich ist.

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An Prüflinge angeschlossene Leitungen können bei hohen Frequenzen als Antenne wirken. Die Anregung hängt wesentlich von der Art des Leitungsanschlusses ab. Bei Frequenzen oberhalb von einem GHz ist zu klären, welchen Unterschied die symmetrische bzw. eine Speisung der Leitung hat. Es ist zu analysieren, wie sich bei symmetrisch betriebenen Leitungen eine Modenumwandlung eines symmetrischen Signals in ein asymmetrisches Signal entlang der Leitung auf die Störaussendung auswirkt.

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Gemäß EMV-Gesetz muss heute jeder Hersteller eines elektrischen/elektronischen Geräts die Konformität seines Produktes mit den essentiellen Anforderungen des EMV-Gesetzes erklären. Durch die engere Nachbarschaft von Leistungselektronik und Signalelektronik bei geregelten Antriebssystemen steigt der EMV-Aufwand. Für jede Phase der Produktentwicklung sollten daher Analysen zur Erreichung der EMV in einer dem jeweiligen Wissensstand angepassten Tiefe durchgeführt werden. Im Rahmen des Forschungsprojektes sind die möglichen Analysewerkzeuge auf ihre Brauchbarkeit und ihre bevorzugten Einsatzbereiche zu untersuchen und die Grenzen und Möglichkeiten der Werkzeuge zu beschreiben. Alternative Verfahrensmethoden für die numerische Analyse des elektromagnetischen Verhaltens geregelter Elektroantriebe werden analysiert und beschrieben. Das erlangte Wissen wird den beteiligten Firmen verfügbar gemacht.

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Verbindungsstrukturen in komplexen technischen Systemen unterliegen in Ihren Eigenschaften statistischen Schwankungen z.B. bedingt durch Produktionstoleranzen. Ziel des Projektes ist es, Verfahren zur Beurteilung des Einflusses dieser Schwankungen auf das Verhalten elektrischer Größen zu bestimmen. Dafür ist die Behandlung der Übertragungsstruktur als ungleichförmige Leitung notwendig. Hierfür müssen Methoden zur Bestimmung der ungleichförmigen Leitungsparameter sowie die Lösung der daraus resultierenden Matrix-Differentialgleichung entwickelt werden. Auf der Basis dieser deterministischen Verfahren sind  Modelle für die eine stochastische Analyse zu entwickeln. Die entwickelten Modelle und Verfahren sind messtechnisch an Beispielanordnungen zu validieren.

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Zahlreiche Komfortmerkmale in modernen Mittel- und Oberklassefahrzeugen basieren auf Gleichstrommotoren, die oftmals mit elektromechanischen Relais geschaltet werden. Aus Sicht der EMV sind transiente Spannungsimpulse problematisch, die beim Abschalten von Gleichstrommotoren entstehen, da diese in andere Komponenten einkoppeln können. Neben dem Gleichstrom­motor beeinflussen auch das Schaltrelais und ein eventueller Entstörkondensator den resultierenden Impuls. Damit diese Störphänomene bereits während des Entwicklungsprozesses berücksichtigt werden können, sind Modelle notwendig, mit denen sich die resultierenden Impulse abschätzen lassen. Zu diesem Zweck wurde ein SPICE- Modell zur Simulation der zu erwartenden Spannungsimpulse erstellt, welches den Motor und das Schaltrelais als Teilmodelle berücksichtigt. Die Modellparameter wurden aus Herstellerangaben und empirisch ermittelten Daten des realen Motors generiert. Unterschiedliche Lastzustände des Motors können bei der Simulation berücksichtigt werden. Die Simulationsdaten wurden messtechnisch verifiziert.

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Die Notwendigkeit, Positionen von Kabelfehlern zu bestimmen (Ort der elektrischen Leitungsunterbrechung, des Isolationsdefekts, des Kabelschirmfehlers, der Geometrieänderung des Leitungsabschnitts), besteht für verschiedene Anwendungen von Telekommunikations-, Strom-, Daten- und Impulsleitungen. Im Forschungsprojekt wird die Schätzung der Leitungslänge basierend auf Zeit- und Frequenzbereichsmethoden dargestellt und die Simulationsergebnisse werden an Messergebnissen gespiegelt.

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