@inproceedings{22218, author = {{Krauter, Stefan and Böcker, Joachim and Freitag, Christine and Hehenkamp, Burkhard and Hilleringmann, Ulrich and Temmen, Katrin and Klaus, Tobias and Rohrer, Nicolaus and Lehmann, Sven}}, booktitle = {{Tagungsband des 36. PV-Symposiums, 18.-26 Mai 2021}}, isbn = {{978-3-948176-14-3}}, keywords = {{Art-D, Afrika, Resilienz, Resilience, Grid stability, robustness, microgrids}}, location = {{Staffelstein / online}}, pages = {{305--309}}, publisher = {{Conexio}}, title = {{{Projekt Art-D Grids: Nachhaltige und stabile Microgrids in Afrika - eine Plattform für Forschung und Lehre für die Entwicklung}}}, year = {{2021}}, } @inproceedings{29899, abstract = {{LLC resonant converters are typically unsuitable to be applied for wide voltage-transfer ratio applications. With a full-bridge inverter, however, they can be operated in a variety of different modulations. Most notably, by permanently turning on one MOSFET and turning off the other MOSFET of the same bridge leg, the LLC can be operated in half-bridge configuration reducing the gain by a factor of two. The resonant capacitor is hereby charged to an average voltage of half the input voltage. In this modulation, however, the switch that is permanently turned on is stressed by the complete resonant current while exhibiting no switching losses. This paper proves that the frequency-doubler modulation can better balance the losses among all MOSFETs and should be the preferred mode of operation favored over the conventional half-bridge modulation. This paper analyzes the beneficial loss distribution, proposes an on-the-fly morphing modulation and discusses potential operating strategies to further reduce the junction temperature. Furthermore, it is shown that this modulation can also be altered to achieve the asymmetrical LLC operation. Experimental measurement results show that the modulation results in a substantial decrease of the maximum MOSFET temperature and shows that the converter can be smoothly transitioned during operation from full-bridge modulation to the frequency-doubler half-bridge operation and back.}}, author = {{Rehlaender, Philipp and Unruh, Roland and Hankeln, Lars and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe)}}, isbn = {{978-9-0758-1537-5}}, keywords = {{Resonant converter, High frequency power converter, Switched-mode power supply, Converter control, Control methods for electrical systems}}, location = {{Ghent, Belgium}}, publisher = {{IEEE}}, title = {{{Frequency-Doubler Modulation for Reduced Junction Temperatures for LLC Resonant Converters Operated in Half-Bridge Configuration}}}, doi = {{10.23919/EPE21ECCEEurope50061.2021.9570674}}, year = {{2021}}, } @unpublished{29655, author = {{Kirchgässner, Wilhelm and Wallscheid, Oliver and Böcker, Joachim}}, booktitle = {{arXiv preprint arXiv:2103.16323}}, title = {{{Thermal Neural Networks: Lumped-Parameter Thermal Modeling With State-Space Machine Learning}}}, year = {{2021}}, } @article{21252, author = {{Traue, Arne and Book, Gerrit and Kirchgässner, Wilhelm and Wallscheid, Oliver}}, issn = {{2162-237X}}, journal = {{IEEE Transactions on Neural Networks and Learning Systems}}, pages = {{1--10}}, title = {{{Toward a Reinforcement Learning Environment Toolbox for Intelligent Electric Motor Control}}}, doi = {{10.1109/tnnls.2020.3029573}}, year = {{2020}}, } @inproceedings{29884, author = {{Böcker, Joachim}}, booktitle = {{2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)}}, publisher = {{IEEE}}, title = {{{Analysis of the Magnetic Skin Effekt in Motors and Inductors}}}, doi = {{10.1109/speedam48782.2020.9161895}}, year = {{2020}}, } @article{21250, author = {{Kirchgässner, Wilhelm and Wallscheid, Oliver and Böcker, Joachim}}, issn = {{0885-8993}}, journal = {{IEEE Transactions on Power Electronics}}, number = {{7}}, pages = {{7480--7488}}, title = {{{Estimating Electric Motor Temperatures with Deep Residual Machine Learning}}}, doi = {{10.1109/tpel.2020.3045596}}, volume = {{36}}, year = {{2020}}, } @inproceedings{29939, abstract = {{In this paper, a full-bridge modular multilevel converter (MMC) and two half-bridge-based MMCs are evaluated for high-current low-voltage e.g. 100 - 400V DC-applications such as electrolysis, arc welding or datacenters with DC-power distribution. Usually, modular multilevel converters are used in high-voltage DC-applications (HVDC) in the multiple kV-range, but to meet the needs of a high-current demand at low output voltage levels, the modular converter concept requires adaptations. In the proposed concept, the MMC is used to step-down the three-phase medium-voltage of 10kV, and provide up to 1 MW to the load. Therefore, each module is extended by an LLC resonant converter to adapt to the specific electrolyzers DC-voltage range of 142 - 220V and to provide galvanic isolation. The six-arm MMC converter with half-bridge modules can be simplified and optimized by removing three arms, and thus halving the number of modules. In addition, the module voltage ripple and capacitor losses are decreased by 22% and 30% respectively. By rearranging the components of the half-bridge MMC to build a MMC consisting of grid-side full-bridge modules, the voltage ripple is further reduced by 78% and capacitor losses by 64%, while ensuring identical costs and volume for all MMCs. Finally, the LLC resonant converter is designed for the most efficient full-bridge MMC. The LLC can not operate at resonance with a fixed nominal module voltage of 770V because the output voltage is varying between 142 - 220V. By decreasing the module voltage down to 600V, additional points of operation can be operated in resonance, and the remaining are closer to resonance. The option to decrease the module voltage down to 600V, increases the number of required modules per arm from 12 to 15, which requires to balance the losses of the LLCs and the grid-side stages.}}, author = {{Unruh, Roland and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe)}}, keywords = {{Multilevel converters, Resonant converter, High voltage power converters, ZVS Converters, Combination MMC LLC}}, location = {{Lyon, France}}, publisher = {{IEEE}}, title = {{{Evaluation of MMCs for High-Power Low-Voltage DC-Applications in Combination with the Module LLC-Design}}}, doi = {{10.23919/epe20ecceeurope43536.2020.9215687}}, year = {{2020}}, } @inproceedings{29894, author = {{Rehlaender, Philipp and Tikhonov, Sergey and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe)}}, publisher = {{IEEE}}, title = {{{Dual Interleaved 3.6 kW LLC Converter Operating in Half-Bridge, Full-Bridge and Phase-Shift Mode as a Single-Stage Architecture of an Automotive On-Board DC-DC Converter}}}, doi = {{10.23919/epe20ecceeurope43536.2020.9215736}}, year = {{2020}}, } @article{21558, author = {{Brosch, Anian and Hanke, Sören and Wallscheid, Oliver and Böcker, Joachim}}, issn = {{0885-8993}}, journal = {{IEEE Transactions on Power Electronics}}, pages = {{2179--2190}}, title = {{{Data-Driven Recursive Least Squares Estimation for Model Predictive Current Control of Permanent Magnet Synchronous Motors}}}, doi = {{10.1109/tpel.2020.3006779}}, year = {{2020}}, } @inproceedings{29956, author = {{Stille, Karl Stephan Christian and Weber, Daniel and Lange, Jarren and Vogt, Thorsten and Wallscheid, Oliver and Böcker, Joachim}}, booktitle = {{2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)}}, location = {{Sorrent, Italy}}, publisher = {{IEEE}}, title = {{{Emulation of Microgrids for Research and Validation of Control and Operation Strategies}}}, doi = {{10.1109/speedam48782.2020.9161971}}, year = {{2020}}, } @inproceedings{29896, abstract = {{Automotive DC-DC converters linking the traction battery to the auxiliary battery are characterized by the wide input and output voltage ranges resulting from the varying state-of-charge of the traction and auxiliary battery. The wide voltage transfer ratio needs to be covered for the entire load range conventionally requiring two-stage converter architectures. Considering a less complex single-stage solution potentially enabling cost and weight advantages, traditional LLC converters are unsuitable topologies since it results in a too wide operating frequency range. Most alternative topology candidates show comparable difficulties. To overcome this issue, the gain range of the LLC with full-bridge inverter can be extended by operation in half-bridge mode for low voltage transfer ratios. Phase-shift operation is utilized for intermediate gains and low loads. This paper describes a detailed design methodology for the resonant tank. The experimental results with a peak efficiency of 96.5 % and a power density of 2.1 kW/l prove the proposed concept.}}, author = {{Rehlaender, Philipp and Grote, Tobias and Tikhonov, Sergey and Mario, Schröder and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{PCIM Europe digital days 2020}}, location = {{Nürnberg}}, title = {{{A 3,6 kW Single-Stage LLC Converter Operating in Half-Bridge, Full-Bridge and Phase-Shift Mode for Automotive Onboard DC-DC Conversion}}}, year = {{2020}}, } @inproceedings{29898, abstract = {{An onboard DC-DC converter connects the high voltage traction battery to the low voltage auxiliary battery of an EV. It has to provide power across a wide range of input and output voltages. This paper presents the design and evaluation of an economical two-stage converter concept consisting of a first-stage boost converter and a second-stage LLC converter. While for low input voltages, the boost converter can supply the second-stage LLC with the optimum bulk voltage, for high input voltages, the boost converter is turned off and the LLC regulates the output voltage on its own. Whereas this is unproblematic for high output currents, for low loads high switching frequencies become necessary. For this purpose, the LLC needs to be designed for a wide gain range. Traditionally, this is achieved through a small magnetizing inductance resulting in increased conduction losses. If an asymmetric duty cycle operation is used to cover the low gains at low output current, the LLC can be optimized for a better efficiency. A prototype design proves that the asymmetric duty cycle operation is feasible to achieve a wide gain range at a high efficiency whereas the conventional design achieves very poor efficiencies.}}, author = {{Rüschenbaum, Tobias and Rehlaender, Philipp and Ha, Phuong and Grote, Tobias and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{PCIM Europe digital days 2020}}, title = {{{Two-Stage Automotive DC-DC Converter Design with Wide Voltage-Transfer Range Utilizing Asymmetric LLC Operation}}}, year = {{2020}}, } @inproceedings{29874, abstract = {{LLC resonant converters generally employ MOSFETs in the inverter stage, which can be of half-bridge (HB) or full-bridge (FB) type. The generally weak intrinsic (body) diodes of the MOSFETs cause turn-on losses when being forced to hard current commutations finally leading to the components self-destruction when operated constantly in this way. Consequently, zero-voltage switching (ZVS) operation is more or less essential in a silicon (Si) MOSFET-based HB or FB. To ensure ZVS, the LLC is operated in the inductive region, i.e. with lagging resonant current. On the contrary, IGBTs show dominant turn-off losses and therefore are conventionally not applied in LLCs typically requiring high switching frequencies to achieve low output voltages. Yet, if the LLC is intentionally designed for the capacitive region, i. e. operation with leading current, zero-current switching (ZCS) enabling IGBTs in the inverter stage can be ensured. This paper explores in detail the LLC in the capacitive operating region and gives design considerations for a capacitive LLC utilizing both robust and cost-efficient IGBTs for an exemplary 2.2 kW automotive on-board DC-DC converter application. The results of a loss analysis show that the LLC resonant converter can be operated well in the capacitive region. In the given case, significantly lower overall and 30 % lower inverter stage losses are achieved in the thermally relevant worst-case comparison with an inductive LLC based on Si MOSFETs.}}, author = {{Urbaneck, Daniel and Rehlaender, Philipp and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{PCIM Europe digital days 2020}}, location = {{Nürnberg}}, title = {{{LLC Converter Design in Capacitive Operation utilizes ZCS for IGBTs – a Concept Study for a 2.2 kW Automotive DC-DC Stage}}}, year = {{2020}}, } @article{30033, author = {{Stender, Marius and Wallscheid, Oliver and Böcker, Joachim}}, issn = {{0278-0046}}, journal = {{IEEE Transactions on Industrial Electronics}}, keywords = {{Electrical and Electronic Engineering, Control and Systems Engineering}}, number = {{9}}, pages = {{8646--8656}}, publisher = {{Institute of Electrical and Electronics Engineers (IEEE)}}, title = {{{Comparison of Gray-Box and Black-Box Two-Level Three-Phase Inverter Models for Electrical Drives}}}, doi = {{10.1109/tie.2020.3018060}}, volume = {{68}}, year = {{2020}}, } @inproceedings{30036, author = {{Stender, Marius and Wallscheid, Oliver and Böcker, Joachim}}, booktitle = {{2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)}}, publisher = {{IEEE}}, title = {{{Accurate Torque Estimation for Induction Motors by Utilizing Globally Optimized Flux Observers}}}, doi = {{10.1109/speedam48782.2020.9161955}}, year = {{2020}}, } @article{29649, author = {{Heid, Stefan and Weber, Daniel and Bode, Henrik and Hüllermeier, Eyke and Wallscheid, Oliver}}, journal = {{Journal of Open Source Software}}, number = {{54}}, pages = {{2435}}, title = {{{OMG: A scalable and flexible simulation and testing environment toolbox for intelligent microgrid control}}}, volume = {{5}}, year = {{2020}}, } @article{29644, author = {{Bode, Henrik and Heid, Stefan and Weber, Daniel and Hüllermeier, Eyke and Wallscheid, Oliver}}, journal = {{arXiv preprint arXiv:2005.04869}}, title = {{{Towards a scalable and flexible simulation and testing environment toolbox for intelligent microgrid control}}}, year = {{2020}}, } @inproceedings{29641, author = {{Gedlu, Emebet Gebeyehu and Wallscheid, Oliver and Böcker, Joachim}}, booktitle = {{The 10th International Conference on Power Electronics, Machines and Drives (PEMD 2020)}}, pages = {{937–942}}, title = {{{Permanent magnet synchronous machine temperature estimation using low-order lumped-parameter thermal network with extended iron loss model}}}, volume = {{2020}}, year = {{2020}}, } @inproceedings{30339, author = {{Ahmmad, Mohsin Ejaz and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM digital days)}}, location = {{Nuremberg, Germany}}, publisher = {{IEEE}}, title = {{{Practical Implementation and Verification of Simple-to-Implement Digital Current Observer for Half-Bridge Topologies}}}, year = {{2020}}, } @misc{30362, author = {{Schafmeister, Frank}}, pages = {{39}}, title = {{{Apparatus and method for charging an electric battery vehicle}}}, year = {{2020}}, }