@inproceedings{BuedelHerkommerKuhlmannetal.2021, author = {B{\"u}del, Johannes and Herkommer, Christian and Kuhlmann, Kai and Teigelk{\"o}tter, Johannes}, title = {Advanced DC-charging Methods for Traction Drives with Dual Two-Level Inverter During Machine Operation}, series = {2021 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe)}, booktitle = {2021 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe)}, doi = {10.23919/EPE21ECCEEurope50061.2021.9570611}, year = {2021}, abstract = {This paper aims to present a concept and especially developed control methods for an open-end winding traction drive, powered by a dual two-level inverter, where the two separate energy sources can be charged via a DC grid during operation and while being standstill. For achieving a high quality DC-current, the parasitic Back-EMF harmonics of the electrical machine will be compensated. The application aims to achieve high utilisation of the electric vehicle in combination with a partly equipped trolley wire net.}, subject = {Wechselrichter}, language = {en} } @article{KoehlerWoelfelCibaetal.2018, author = {K{\"o}hler, Tim and W{\"o}lfel, Maximilian and Ciba, Manuel and Bochtler, Ulrich and Thielemann, Christiane}, title = {Terrestrial Trunked Radio (TETRA) exposure of neuronal in vitro networks}, series = {Environmental Research}, volume = {2018}, journal = {Environmental Research}, number = {162}, doi = {10.1016/j.envres.2017.12.007}, pages = {1 -- 7}, year = {2018}, abstract = {Terrestrial Trunked Radio (TETRA) is a worldwide common mobile communication standard, used by authorities and organizations with security tasks. Previous studies reported on health effects of TETRA, with focus on the specific pulse frequency of 17.64 Hz, which affects calcium efflux in neuronal cells. Likewise among others, it was reported that TETRA affects heart rate variability, neurophysiology and leads to headaches. In contrast, other studies conclude that TETRA does not affect calcium efflux of cells and has no effect on people's health. In the present study we examine whether TETRA short- and long-term exposure could affect the electrophysiology of neuronal in vitro networks. Experiments were performed with a carrier frequency of 395 MHz, a pulse frequency of 17.64 Hz and a differential quaternary phase-shift keying (π/4 DQPSK) modulation. Specific absorption rates (SAR) of 1.17 W/kg and 2.21 W/kg were applied. In conclusion, the present results do not indicate any effect of TETRA exposure on electrophysiology of neuronal in vitro networks, neither for short-term nor long-term exposure. This applies to the examined parameters spike rate, burst rate, burst duration and network synchrony.}, subject = {Neuronales Netz}, language = {en} } @article{OsterDausErbesetal.2016, author = {Oster, Stefan and Daus, Andreas and Erbes, Christian and Goldhammer, Michael and Bochtler, Ulrich and Thielemann, Christiane}, title = {Long-term electromagnetic exposure of developing neuronal networks: A flexible experimental setup}, series = {Bioelectromagnetics}, volume = {2016}, journal = {Bioelectromagnetics}, number = {37}, doi = {10.1002/bem.21974}, pages = {264 -- 278}, year = {2016}, abstract = {Neuronal networks in vitro are considered one of the most promising targets of research to assess potential electromagnetic field induced effects on neuronal functionality. A few exposure studies revealed there is currently no evidence of any adverse health effects caused by weak electromagnetic fields. Nevertheless, some published results are inconsistent. Particularly, doubts have been raised regarding possible athermal biological effects in the young brain during neuronal development. Therefore, we developed and characterized a flexible experimental setup based on a transverse electromagnetic waveguide, allowing controlled, reproducible exposure of developing neuronal networks in vitro. Measurement of S-parameters confirmed very good performance of the Stripline in the band of 800-1000 MHz. Simulations suggested a flexible positioning of cell culture dishes throughout a large exposure area, as specific absorption rate values were quite independent of their position (361.7 ± 11.4 mW/kg) at 1 W, 900 MHz. During exposure, thermal drift inside cellular medium did not exceed 0.1 K. Embryonic rat cortical neurons were cultivated on microelectrode array chips to non-invasively assess electrophysiological properties of electrogenic networks. Measurements were taken for several weeks, which attest to the experimental setup being a reliable system for long-term studies on developing neuronal tissue.}, subject = {Neuronales Netz}, language = {en} } @inproceedings{DausOsterErbesetal.2013, author = {Daus, Andreas and Oster, Stefan and Erbes, Christian and Goldhammer, Michael and Bochtler, Ulrich and Thielemann, Christiane}, title = {Electromagnetic exposure of neuronal networks on microelectrode arrays}, series = {U.R.S.I. Landesausschuss in der Bundesrepublik Deutschland e.V., Kleinheubacher Tagung, Miltenberg, Abstracts}, booktitle = {U.R.S.I. Landesausschuss in der Bundesrepublik Deutschland e.V., Kleinheubacher Tagung, Miltenberg, Abstracts}, pages = {29 -- 30}, year = {2013}, subject = {Neuronales Netz}, language = {en} } @inproceedings{OsterDausGoldhammeretal.2013, author = {Oster, Stefan and Daus, Andreas and Goldhammer, Michael and Bochtler, Ulrich and Thielemann, Christiane}, title = {A Flexible RF Exposure Setup for Long-term Electrophysiological Investigations on Biological Samples in Vitro}, series = {Progress In Electromagnetics Research Symposium Abstracts, Stockholm, Schweden}, booktitle = {Progress In Electromagnetics Research Symposium Abstracts, Stockholm, Schweden}, year = {2013}, subject = {Neuronales Netz}, language = {en} } @inproceedings{GoldhammerDausThielemannetal.2009, author = {Goldhammer, Michael and Daus, Andreas and Thielemann, Christiane and Bochtler, Ulrich}, title = {Flexible measurement setup for electromagnetic exposition of biological samples}, series = {BioEM 2009, Davos, Switzerland}, booktitle = {BioEM 2009, Davos, Switzerland}, year = {2009}, subject = {Elektromagnetische Strahlung}, language = {en} } @inproceedings{DausGoldhammerBochtleretal.2009, author = {Daus, Andreas and Goldhammer, Michael and Bochtler, Ulrich and Thielemann, Christiane}, title = {Electromagnetic exposition of neuronal networks in vitro}, series = {Radiofrequency fields and health}, booktitle = {Radiofrequency fields and health}, organization = {Forschungsgemeinschaft Funk, Stuttgart}, year = {2009}, subject = {Neuronales Netz}, language = {en} } @inproceedings{DausGoldhammerBochtleretal.2010, author = {Daus, Andreas and Goldhammer, Michael and Bochtler, Ulrich and Thielemann, Christiane}, title = {A new approach for the investigation of long-term effects of RF radiation on cells}, series = {28th Progress In Electromagnetics Research Symposium 2010, Cambridge}, booktitle = {28th Progress In Electromagnetics Research Symposium 2010, Cambridge}, year = {2010}, subject = {Hochfrequenz}, language = {en} } @inproceedings{KoehlerWoelfelBochtleretal.2016, author = {K{\"o}hler, Tim and W{\"o}lfel, Maximilian and Bochtler, Ulrich and Thielemann, Christiane}, title = {TETRA specific long-term exposure of neuronal in vitro networks}, series = {BioEM2016}, booktitle = {BioEM2016}, year = {2016}, subject = {Neuronales Netz}, language = {en} } @article{DasMahatoChandanetal.2024, author = {Das, Durbanjali and Mahato, Bidyut and Chandan, Bikramaditya and Joshi, Hitesh and Mahto, Kailash Kumar and Das, Priyanath and Fotis, Georgios and Vita, Vasiliki and Mann, Michael}, title = {A New Cascaded Multilevel Inverter for Modular Structure and Reduced Passive Components}, series = {Electronics}, volume = {13}, journal = {Electronics}, number = {17}, publisher = {MDPI AG}, issn = {2079-9292}, doi = {http://dx.doi.org/10.3390/electronics13173566}, year = {2024}, abstract = {In high-power applications, achieving adequate power quality in power converter design is accomplished by utilizing multilevel inverters instead of using two-level and three-level inverters. The device generates a sinusoidal output voltage, which results in reduced total harmonic distortion and lower voltage stress on the switches and leads to lower electromagnetic interference, making it suitable for use in renewable energy applications. However, to illustrate the advantages mentioned above, a significant number of switching devices and DC sources are necessary while raising the voltage levels. This article proposes an asymmetrical voltage generation method, which operates in a ratio of 1:5 and generates 25 levels using 11 power switches. The topology is modular in structure, and each module has a lower component count, which significantly reduces the overall cost. The proposed topology is capable of generating negative output voltage levels without the use of an H-bridge configuration, where only three switches are used to generate any voltage levels. The functionality of the developed module is amended by fixing different voltage values in DC sources. This article also presents a comprehensive examination of the circuit and the functioning of various voltage levels. The advantages of the proposed inverter have been demonstrated by comparative research with the currently existing MLI topologies. Ultimately, both the simulation and experimental findings validated the practical capabilities.}, subject = {Mehrpunktwechselrichter}, language = {en} } @inproceedings{NeumaierProbstWoelfeletal.2025, author = {Neumaier, Marcel and Probst, Anne-Catherine and W{\"o}lfel, Maximilian and Bochtler, Ulrich}, title = {Performance Analysis in a Digital TETRA-Simulcast System}, series = {2025 16th German Microwave Conference (GeMiC)}, booktitle = {2025 16th German Microwave Conference (GeMiC)}, year = {2025}, abstract = {In radio communication of mission-critical services, resilient solutions are strongly required to account for public safety. Additionally to the cellular network based on the professional mobile radio European standard TETRA, a digital TETRA-simulcast system is proposed as a redundant network to ensure area coverage in case of base station failure caused e.g. by disasters. This paper presents a preliminary study about network planning of a frequency-efficient digital TETRA-simulcast system to be physically deployed in a hilly region of Germany. Coverage as well as ray tracing analysis and channel modeling were performed by simulations and prove to be helpful tools for the systematic optimization of system performances, especially with regard to the control of intersymbol interference in overlapping zones.}, subject = {TETRA, Telekommunikation}, language = {en} }