@article{KralHaumerHaigisetal., author = {Kral, Christian and Haumer, Anton and Haigis, Matthias and Lang, Hermann and Kapeller, Hansj{\"o}rg}, title = {Comparison of a CFD Analysis and a Thermal Equivalent Circuit Model of a TEFC Induction Machine With Measurements}, series = {IEEE Transactions on Energy Conversion}, volume = {24}, journal = {IEEE Transactions on Energy Conversion}, number = {4}, publisher = {IEEE}, issn = {0885-8969}, doi = {10.1109/TEC.2009.2025428}, pages = {809 -- 818}, abstract = {For a totally enclosed fan-cooled induction machine, two methods of numerical analysis are compared with measurements. The first numerical method is based on computational fluid dynamics (CFDs) and the second one uses a thermal equivalent circuit (TEC). For the analysis based on CFD, a 3-D induction machine including housing is modeled. The numeric solution of the flow equations is determined for stationary temperature distributions. For the TEC, a discretized one-and-a-half-dimensional model of the induction machine is considered. With the TEC model, stationary and transient operating conditions can be simulated. Measurement results are determined by iron-copper-nickel sensors embedded in the stator winding and the housing, as well as by an IR sensor for measuring the rotor temperature. With these measurement signals, stationary and transient operating conditions can be analyzed. For stationary operating conditions, additionally, the housing temperatures are determined by an IR camera. The investigated simulation and measurement methods reveal different local and global temperatures, and thus, only certain aspects and characteristics of the obtained temperatures can be compared. Nevertheless, certain conclusions can be drawn from comparing these aspects considering the actual restrictions of each of the applied methods.}, 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{GrabnerGraggerKapelleretal., author = {Grabner, Christian and Gragger, Johannes V. and Kapeller, Hansj{\"o}rg and Haumer, Anton and Kral, Christian}, title = {Sensorless PM-Drive Aspects}, 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_3}, pages = {25 -- 35}, abstract = {The development procedure of permanent magnet drives for sensor less operation beginning from standstill under overload conditions has to consider different design aspects coevally. First, the robust rotor position sensing by test signal enforces a design with a strongly different behavior of the spatial dq-oriented differential inductance values. Therefore, the interior rotor magnet array arrangement is from principle predestinated for the controlled sensor less mode including standstill. Fortunately, in order to reduce costs, the distinct reluctance torque capability of such interior magnet arrangement is additionally used for a significantly increased torque by applying a pre-oriented stator current space vectors within the quasi-steady control.}, language = {en} }