@inproceedings{KofianiNonnWierzbickietal., author = {Kofiani, Kirki and Nonn, Aida and Wierzbicki, Tomasz and Kalwa, Christoph and Walters, Carey}, title = {Experiments and fracture modeling of high-strength pipelines for high and low stress triaxiality}, series = {22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012), Rhodes, Greece, June 2012}, booktitle = {22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012), Rhodes, Greece, June 2012}, abstract = {This paper provides results from a comprehensive study on mechanical characterization of high-strength pipeline steel, grade X100 using experimental and numerical methods. The material was characterized for anisotropic plasticity, fracture initiation for various states of stress, (pre-cracked) fracture toughness and uncracked ductility. The experimental program included tests on flat butterfly-shaped, central hole, notched and circular disk specimens for low stress triaxiality levels; as well as tests on round notched bar specimens and SENT fracture mechanics tests, for high values of stress triaxiality. This program covered a wide range of stress conditions and demonstrated its effect on the material resistance. Parallel to the experimental study, detailed numerical investigations were carried out to simulate all different experimental tests. Using an inverse method, a 3-parameter calibration was performed on the Modified Mohr-Coulomb (MMC) fracture model. Subsequently, the predictive capabilities of the MMC were evaluated by the comparison to the fracture toughness tests results, used extensively in the pipeline industry. The capabilities of the MIT fracture model have been demonstrated on an example of high strength offshore steel, X100. The outcome of this study was not only to provide, the overall characterization of the fracture behavior of this material as an example, but also to present the methodology on how to use the MMC model as a practical tool in pipeline design.}, language = {en} } @inproceedings{NonnKalwa, author = {Nonn, Aida and Kalwa, Christoph}, title = {Failure modeling of pipeline X100 Material in temperature transition region}, series = {22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012), Rhodes, Greece}, booktitle = {22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012), Rhodes, Greece}, abstract = {This paper focuses on the characterization of the fracture performance of X100 material in transition temperature region using both experimental and numerical methods. The ductile fracture has been analyzed using tests on round notched bar specimens and standard fracture mechanics tests performed at room temperature. In previous publications the damage model Gurson-Tvergaard-Needleman (GTN) has been applied and verified by existing experimental data to describe ductile fracture behavior. The brittle fracture and the fracture in temperature transition region have been studied by means of deep and shallow notched SENB specimens at two different temperatures T=- 80°C and -40°C. Besides elastic-plastic analyses to quantify constraint levels for different initial crack configurations at the onset of cleavage fracture, the brittle failure has been described using modified Beremin model. The influence of the stable crack growth on the cleavage failure probability in temperature transition region has been captured by coupling the ductile fracture model (GTN) with the modified Beremin model. Finally, examples have been presented for the practical application of the numerical results on the fracture assessment of the flawed high-strength pipelines.}, language = {en} } @article{OstermeierMottokKnorretal., author = {Ostermeier, Daniel and Mottok, J{\"u}rgen and Knorr, Christine and Huber, Michael}, title = {Competence Atlas for Save and Green Road Vehicles in the Electro Mobility Cluster Regensburg}, series = {Applied Research Conference 2012 (ARC 2012) 25./26. June 2012, Nuremberg}, journal = {Applied Research Conference 2012 (ARC 2012) 25./26. June 2012, Nuremberg}, editor = {Mottok, J{\"u}rgen and Ziemann, Olaf}, pages = {86 -- 92}, language = {en} } @inproceedings{Mottok, author = {Mottok, J{\"u}rgen}, title = {Migration path for secure and economic smart power grid devices with transitional smart metering support}, series = {2nd Applied Research Conference 2012 (ARC 2012), 25./26. June 2012, Nuremberg}, booktitle = {2nd Applied Research Conference 2012 (ARC 2012), 25./26. June 2012, Nuremberg}, pages = {64 -- 70}, language = {en} } @inproceedings{NickSchorerMottok, author = {Nick, Matthias and Schorer, Michael and Mottok, J{\"u}rgen}, title = {Feasibility Study of a Build System Performing Automated Builds Based on Model-Based Build Descriptions}, series = {2nd Applied Research Conference 2012 (ARC 2012), 25./26. June 2012, Nuremberg}, booktitle = {2nd Applied Research Conference 2012 (ARC 2012), 25./26. June 2012, Nuremberg}, editor = {Mottok, J{\"u}rgen and Ziemann, Olaf}, publisher = {Shaker}, address = {Aachen}, pages = {71 -- 75}, language = {en} } @techreport{OPUS4-2062, title = {Energienutzungsplan f{\"u}r die Gemeinde Sinzing}, editor = {Neuleitner, Nikolaus and Steffens, Oliver}, organization = {Hochschule f{\"u}r ANgewandte Wissenschaften Regensburg}, language = {de} } @inproceedings{BaeumlHaumerKapelleretal., author = {B{\"a}uml, T. and Haumer, Anton and Kapeller, H. and Starzinger, J. and Farzi, P.}, title = {Impact of inverter pulse inhibition on the high-voltage supply system of an electric vehicle — A simulative approach}, series = {2011 IEEE Vehicle Power and Propulsion Conference (VPPC 2011) : Powering sustainable transportation ; Chicago, Illinois, USA, 06. - 09.09.2011}, booktitle = {2011 IEEE Vehicle Power and Propulsion Conference (VPPC 2011) : Powering sustainable transportation ; Chicago, Illinois, USA, 06. - 09.09.2011}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-61284-248-6}, doi = {10.1109/VPPC.2011.6043159}, pages = {1 -- 5}, abstract = {This paper deals with a simulative approach for investigating the impact of inverter pulse inhibition during field weakening operation of permanent magnet synchronous machines and asynchronous induction machines. The modelling and simulation language Modelica is used to design models for the vehicle, the electric machine and the inverter in different abstraction levels. It is shown that when using a permanent magnet synchronous machine, a sudden breakdown of the field weakening current causes induction of high voltages in the stator windings. Hence, the electric system of the vehicle has to be protected against the resulting high currents. Furthermore precautions have to be taken to avoid dangerous driving conditions because of high braking torques in an inverter fault operation mode. In the case of the asynchronous induction machine an inverter pulse inhibition poses no big problem, neither for the electric system of the vehicle, nor the driver.}, language = {en} } @inproceedings{HongHyunKangetal., author = {Hong, Jongman and Hyun, Doosoo and Kang, Tae-june and Lee, Sang Bin and Kral, Christian and Haumer, Anton}, title = {Detection and classification of rotor demagnetization and eccentricity faults for PM synchronous motors}, series = {2011 IEEE Energy Conversion Congress and Exposition (ECCE 2011) : Energy conversion innovation for a clean energy future ; Phoenix, Arizona, USA, 17.-22.09.2011}, booktitle = {2011 IEEE Energy Conversion Congress and Exposition (ECCE 2011) : Energy conversion innovation for a clean energy future ; Phoenix, Arizona, USA, 17.-22.09.2011}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4577-0542-7}, issn = {2329-3721}, doi = {10.1109/ECCE.2011.6064103}, pages = {2512 -- 2519}, abstract = {Condition monitoring of rotor problems such as demagnetization and eccentricity in permanent magnet synchronous motors (PMSM) is essential for guaranteeing high motor performance, efficiency, and reliability. However, there are many limitations to the off-line and on-line methods currently used for PMSM rotor quality assessment. In this paper, an inverter-embedded technique for automated detection and classification of PMSM rotor faults is proposed as an alternative. The main concept is to use the inverter to perform a test whenever the motor is stopped, to detect rotor faults independent of operating conditions or load torque oscillations, which is not possible with motor current signature analysis (MCSA). The d-axis is excited with a dc+ac signal, and the variation in the inductance pattern due to the change in the degree of magnetic saturation caused by demagnetization or eccentricity is observed for fault detection. An experimental study on a 7.5kW PMSM verifies that demagnetization and eccentricity can be detected and classified independent of the load with high sensitivity.}, language = {en} } @inproceedings{HongLeeKraletal., author = {Hong, Jongman and Lee, Sang Bin and Kral, Christian and Haumer, Anton}, title = {Detection of airgap eccentricity for permanent magnet synchronous motors based on the d-axis inductance}, series = {8th IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics \& Drives (SDEMPED), 2011 // 05. - 08.09.2011, Bologna, Italy}, booktitle = {8th IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics \& Drives (SDEMPED), 2011 // 05. - 08.09.2011, Bologna, Italy}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4244-9301-2}, doi = {10.1109/DEMPED.2011.6063651}, pages = {378 -- 384}, abstract = {The majority of the work performed for detecting eccentricity faults for permanent magnet synchronous motors (PMSM) focus on motor current signature analysis (MCSA), as it provides continuous on-line monitoring with existing current sensors. However, MCSA cannot be applied under nonstationary conditions and cannot distinguish faults with load torque oscillations, which are limitations for many PMSM drive applications. In this paper, it is shown that the d-axis inductance, L d , decreases with increase in the severity of eccentricity due to the change in the degree of magnetic saturation, and it is proposed as a new fault indicator. The inverter can be used to perform a standstill test automatically whenever the motor is stopped, to measure L d for eccentricity testing independent of load variations or oscillations, which is not possible with MCSA. An FE and experimental study on a 10hp PMSM verifies that eccentricity can be detected independent of the load with high sensitivity and reliability.}, language = {en} } @inproceedings{HaumerKral, author = {Haumer, Anton and Kral, Christian}, title = {Modeling a Mains connected PWM Converter with Voltage-Oriented Control}, series = {Proceedings of the 8th International Modelica Conference, Technical Univeristy, Dresden, Germany, 20.-22.03.2011}, booktitle = {Proceedings of the 8th International Modelica Conference, Technical Univeristy, Dresden, Germany, 20.-22.03.2011}, publisher = {Link{\"o}ping University Electronic Press}, doi = {10.3384/ecp11063388}, pages = {388 -- 397}, abstract = {The majority of industrial controlled induction machine drives are connected to the mains via a diode bridge. However; if reduction of harmonic currents and / or regenerative operation is desired; replacing the diode bridge by an active front-end (AFE) is required. This paper describes two models of an AFE: a power balance model disregarding switching effects; and an ideal switching model of a pulse width modulation (PWM) converter. Both models are controlled utilizing space phasors in a voltage oriented reference frame. Voltage oriented control (VOC) of the mains converter can be compared with field oriented control (FOC) of a machine converter. Design and parametrization of the main parts—synchronization with mains voltage; current controller and DC voltage controller—are described in detail. Additionally; simulation results proving the implementation and demonstrating possible investigations as well as an outlook on further enhancements are presented.}, language = {en} } @inproceedings{JungreuthmayerBaumlWinteretal., author = {Jungreuthmayer, C. and Bauml, T. and Winter, O. and Ganchev, M. and Kapeller, H. and Haumer, Anton and Kral, Christian}, title = {Heat and fluid flow analysis of an internal permanent magnet synchronous machine by means of computational fluid dynamics}, series = {2011 IEEE International Electric Machines \& Drives Conference (IEMDC 2011) ; Niagara Falls, Ontario, Canada, 15 - 18 May 2011}, booktitle = {2011 IEEE International Electric Machines \& Drives Conference (IEMDC 2011) ; Niagara Falls, Ontario, Canada, 15 - 18 May 2011}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4577-0060-6}, doi = {10.1109/IEMDC.2011.5994651}, pages = {515 -- 520}, abstract = {This paper presents a comprehensive computational fluid (CFD) model of a radial flux permanent magnet synchronous machine with interior magnets. In the CFD model the water jacket cooling and a simplified model of the topology of the distributed stator winding are considered. The heat sources of the CFD model are determined from a finite element analysis of the machine. The numerically determined temperature distributions of the machine are compared with measurement results from sensors located both in the stator and rotor. The particular focus of this paper is the analysis of the temperatures and the heat flow in the air gap and from the stator winding head and the rotor to the inner air.}, language = {en} } @inproceedings{KralHaumer, author = {Kral, Christian and Haumer, Anton}, title = {The New FundamentalWave Library for Modeling Rotating Electrical Three Phase Machines}, series = {Proceedings of the 8th International Modelica Conference; March 20th-22nd; Technical Univeristy; Dresden; Germany}, booktitle = {Proceedings of the 8th International Modelica Conference; March 20th-22nd; Technical Univeristy; Dresden; Germany}, publisher = {University Electronic Press}, address = {Link{\"o}ping}, isbn = {978-91-7393-096-3}, issn = {1650-3686}, doi = {10.3384/ecp11063170}, pages = {170 -- 179}, abstract = {This paper introduces the new FundemantalWave library which is included in the Modelica Standard Library 3.2. The presented Modelica package provides models and components of rotating electrical three phase machines. The presented electrical machine models are fully compatible with the original Machines library of the electrical domain but rely on the concept of the magnetic potential and magnetic flux fundamental waves. In this article; the connector concept; the components and electric machine models of the FundemantalWave package will be explained. Additionally; the didactic advantages and the flexibility of the proposed package in with respect to considering more enhanced and sophisticated effects will be discussed.}, language = {en} } @incollection{KralHaumer, author = {Kral, Christian and Haumer, Anton}, title = {Object Oriented Modeling of Rotating Electrical Machines}, series = {Advances in Computer Science and Engineering}, booktitle = {Advances in Computer Science and Engineering}, editor = {Schmidt, Matthias}, publisher = {IntechOpen}, isbn = {978-953-307-173-2}, doi = {10.5772/15898}, pages = {135 -- 160}, language = {en} } @inproceedings{NonnKalwa, author = {Nonn, Aida and Kalwa, Christoph}, title = {The effect of microstructure, strain hardening and strain rate on the fracture behavior of high strength pipeline steels}, series = {2nd International Conference on Material Modelling (ICMM2), 31th August - 2nd September, 2011 at Mines Paris Tech, France}, booktitle = {2nd International Conference on Material Modelling (ICMM2), 31th August - 2nd September, 2011 at Mines Paris Tech, France}, language = {en} } @techreport{MichaelSternerMareikeJentschUweHolzhammer, author = {Michael Sterner, and Mareike Jentsch, and Uwe Holzhammer,}, title = {Energiewirtschaftliche und {\"o}kologische Bewertung eines Windgas-Angebotes}, publisher = {Fraunhofer Institute for Energy Economics and Energy System Technology}, address = {Kassel}, doi = {10.13140/RG.2.2.25093.68328}, abstract = {In this technical report, (1) the benefits of the new technology for future energy supply are discussed, (2) the climate protection effect of wind gas is discussed, and (3) a reasonable use of wind energy for gas generation is analyzed. In particular, windgas in the heat market is discussed in the utilization cascade of wind energy. The new "power-to-gas" concept opens up completely new possibilities for the integration of renewable energies and for coupling the electricity and gas grids. The Sabatier process, which has been known for 100 years, was first developed for this purpose in 2008 under the leadership of the Center for Solar Energy and Hydrogen Research and Fraunhofer IWES (formerly ISET) with electrolysis to create the "power-to-gas" concept for energy storage. A first pilot plant was built by ZSW Stuttgart on behalf of SolarFuel in 2009. This plant proves the technical feasibility of the new technology. Renewable gas is stored, transported and used as required as control and reserve energy via reconversion, e.g. in combined cycle power plants. In this way, decentrally generated renewable electricity is converted into a CO2 -neutral energy carrier with high energy density. The key advantage of renewable methane is the use of existing infrastructure such as gas grids, gas storage and end-use equipment for the integration of renewable energy. Technologies for natural gas are state of the art and commercially available. Methane also has three times the energy density of hydrogen.}, language = {en} } @article{KralKapellerGraggeretal., author = {Kral, Christian and Kapeller, Hansj{\"o}rg and Gragger, Johannes V. and Haumer, Anton and Kubicek, Bernhard}, title = {Phenomenon Rotor Fault-Multiple Electrical Rotor Asymmetries in Induction Machines}, series = {IEEE Transactions on Power Electronics}, volume = {25}, journal = {IEEE Transactions on Power Electronics}, number = {5}, publisher = {IEEE}, issn = {0885-8993}, doi = {10.1109/TPEL.2009.2037502}, pages = {1124 -- 1134}, abstract = {In the literature, the effects caused by a single or several adjacently broken rotor bars, or a broken end ring are thoroughly investigated. The phenomenon of various nonadjacently broken rotor bars has not been studied so far in detail. Since nonadjacently broken rotor bars may give rise to fault signatures, which are not directly related with the fault extent, it is important to understand the nature of multiple electrical rotor asymmetries in induction machines. The purpose of this paper is thus to investigate several combinations of electrical rotor asymmetries, to systematically elaborate the phenomena related to the broken bars and end rings. In this paper, a sophisticated simulation model and measurement results are used to analyze the phenomenon rotor fault.}, language = {en} } @incollection{KapellerHaumerKraletal., author = {Kapeller, Hansj{\"o}rg and Haumer, Anton and Kral, Christian and Grabner, Christian}, title = {Different Designs of Large Chipper Drives}, series = {Electronic Engineering and Computing Technology}, booktitle = {Electronic Engineering and Computing Technology}, editor = {Ao, Sio-Iong and Gelman, Len}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-90-481-8775-1}, doi = {10.1007/978-90-481-8776-8_9}, pages = {93 -- 104}, abstract = {This paper presents two simulation models for two variants of a large chipper drive used in a paper mill. If a slip ring induction motor is used, the impact of a rotor circuit rheostat with respect to starting behavior and heavy duty load impulses can be examined. Furthermore a speed controlled squirrel cage induction machine will be investigated. The modeling language for both drives is Modelica. The simulation results for both drives are compared and discussed.}, language = {en} } @incollection{KralHaumerGrabner, author = {Kral, Christian and Haumer, Anton and Grabner, Christian}, title = {Determination of Consistent Induction Motor Parameters}, series = {Electronic Engineering and Computing Technology}, volume = {60}, booktitle = {Electronic Engineering and Computing Technology}, editor = {Ao, Sio-Iong and Gelman, Len}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-90-481-8775-1}, doi = {10.1007/978-90-481-8776-8_7}, pages = {71 -- 80}, abstract = {From the rating plate data of an induction motor the nominal efficiency can be determined. Without detailed knowledge of equivalent circuit parameters, partial load behavior cannot be computed. Therefore, a combined calculation and estimation scheme is presented, where the consistent parameters of an equivalent circuit are elaborated, exactly matching the nominal operating point. From these parameters part load efficiencies can be determined.}, language = {en} } @incollection{KralHaumerGrabner, author = {Kral, Christian and Haumer, Anton and Grabner, Christian}, title = {Broken Rotor Bars in Squirrel Cage Induction Machines - Modeling and Simulation}, series = {Electronic Engineering and Computing Technology}, booktitle = {Electronic Engineering and Computing Technology}, editor = {Ao, Sio-Iong and Gelman, Len}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-90-481-8775-1}, doi = {10.1007/978-90-481-8776-8_8}, pages = {81 -- 91}, abstract = {This paper presents a physical model of a squirrel cage induction machine with rotor topology. The machine is modeled in Modelica, an object oriented multi physical modeling system. The presented machine model is used to investigate electrical rotor asymmetries in induction machines. For the case of a single broken rotor bar a simulation model is compared with measurement results.}, language = {en} } @article{GraggerHaumerEinhorn, author = {Gragger, Johannes V. and Haumer, Anton and Einhorn, Markus}, title = {Averaged Model of a Buck Converter for Efficiency Analysis}, series = {Engineering Letters}, volume = {18}, journal = {Engineering Letters}, address = {Hong Kong}, abstract = {In this work a buck converter model for multidomain simulations is proposed and compared with a state-of-the-art buck converter model. In the proposed model no switching events are calculated. By avoiding the computation of the switching events in power electronic models the processing time of multidomain simulations can be decreased significantly. The proposed model calculates any operation point of the buck converter in continuous inductor current conduction mode (CICM) while considering the conduction losses and switching losses. It is possible to utilize the proposed modeling approach also for other dc-to-dc converter topologies. Laboratory test results for the validation of the proposed model are included.}, language = {en} }