In diesem Beitrag werden Berechnungsmodelle für Kurzschlussläufer-Asynchronmaschinen mit gestabtem Kupferkäfig und axial segmentierten Endringen vorgestellt. Die Auslegung des Käfigläufers erfolgt auf Basis eines analytischen Berechnungsansatzes, der die Anbindung zwischen Rotorstäben und Kurzschlussringen gemäß dem eingesetzten Laserschweißverfahren berücksichtigt. Als Vergleichsbasis für die Untersuchungen dienen Rotoren mit Aluminium- und Kupferkäfig, die mittels Druckgussverfahren hergestellt wurden. Anhand der Trennung der Verluste und der aus Leerlauf-, Belastungs- und Kurzschlussmessung ermittelten Ersatzschaltbildparameter werden die Einflüsse des Fertigungsverfahrens und Käfigmaterials auf Wirkungsgrad und Betriebsverhalten diskutiert. Darüber hinaus werden Aspekte zur mechanischen Drehzahlfestigkeit für Anwendungen in der Elektromobilität betrachtet. Mit dem Ziel der Erhöhung der Genauigkeit des Auslegungsprozesses werden numerische Berechnungsansätze zur möglichst exakten Berücksichtigung der Schweißverbindung im Kurzschlussring vorgestellt. / In this paper, calculation models for squirrel cage induction machines with a copper bar cage and axially segmented end rings are presented. For designing the squirrel cage winding, an analytical calculation approach has been developed, which takes into account the joining between rotor bars and end rings according to the laser welding process. As a basis of comparison rotors with aluminum and copper cage are considered, which have been manufactured by means of die casting process. Based on the separation of losses and the equivalent circuit parameters derived from no-load, load and short-circuit measurements, the effect of the manufacturing process and the cage material on the efficiency and the operating behavior are discussed. Furthermore, aspects of mechanical high-speed performance are presented for applications in electric mobility. Aiming on an increased accuracy of the design process, numerical calculation approaches taking into account the welding joint in the short-circuit ring are presented.

This thesis is dealing with thermal fields and the possibilities of their solution by a finite element method. Thereinafter thesis describe assembling a 3D model of induction machine with known parameters, and solving thermal field of the model by Ansys Workbench program and verification of these results by practical measuring on real machine.

This thesis deals with the design of electrical machine for direct drive of cascade liquid pumping system. At the beginning a suitable type of electrical machine and some of its basic parameters are selected. Finally, the 4 pole three phase induction machine powered by alternating voltage 3x400 V was chosen. After that complete design is made with respect to all specified requirements. The designed machine is analyzed with the use of ANSYS Maxwell and RMxprt software. The main outcome of the thesis are dimensional sketches of the engine that will be used as the basis for the production of the prototype.

No description available.

The objective of this thesis is to examine the effect of dynamic induction machine modeling and polynomial static load modeling on the stability of electric power systems and to compare the results with those obtained using constant impedance or constant current load models. A least-squares curve fit algorithm is developed and used in modeling static and quasi-static loads as a function of the bus voltage. A dynamic model for the induction machine which accounts for rotor electrical and mechanical transients is incorporated into the solution algorithm. A test system is analyzed under a variety of loading conditions. The effect of the induction motor .load inertia constants on the system stability are also examined. Plots of load bus voltages during the transient stability period are included. / Master of Science

This thesis deals with a new solution for medium voltage drives. Load Commutated Inverter (LCI) fed synchronous motor drive is a popular solution for high power drive applications. Though the induction machine is more rugged and cheaper compared to the synchronous machine, LCI fed induction motor drive solution is not available. The basic advantage of a synchronous machine over an induction machine is the fact that the synchronous machine can operate at leading power factor. Due to this property load commutation of SCR switches of the LCI is achievable for synchronous machine. On the contrary an induction machine always draws lagging power factor current; this makes it unsuitable as a drive motor for LCI technology. In this thesis a new LCI fed induction motor drive configuration is developed as an alternative for synchronous motor drives. A new variant of six phase induction motor is proposed in this context. The machine is named as Active Reactive Induction Machine (ARIM). The ARIM contains two sets of three-phase windings with isolated neutral. Both the windings have a common axis. One winding carries the active power and can be wound for higher voltage (say 11kV). The other winding supplies the total reactive power of the machine and can be wound for lower voltage (say 2.2 kV). The rotor is a standard squirrel cage. High power induction machines usually demand lesser magnitude of reactive power compared to the total power rating of the machine ( 20% ). Therefore excitation winding has a smaller fraction of the total machine rating compared to the power winding. A VSI with an LC filter supplies reactive power to the ARIM through the excitation winding and ensures leading power factor at the power winding. This is similar to the excitation control of the LCI fed synchronous machine. The direct VSI connection is possible due to the lower voltage rating for the excitation winding. In this way, the VSI voltage rating does not limit the highest motor voltage that can be handled. An LCI supplies the real power into the ARIM from the power winding. The LCI currents are quasi square wave in shape. Therefore they have rich low order harmonic content. They cause 6th and 12th harmonic torque pulsations in the machine. This is a problem for the LCI fed synchronous machine drive. In the proposed drive, the VSI can compensate these low frequency m.m.f. harmonics inside the machine air gap to remove torque pulsation and rotor harmonic losses. The advantage of the proposed topology is that no transformer is required to drive an 11kV machine. It is always desirable to feed sinusoidal voltage and current to both the power winding and the excitation winding. To address this problem, a second configuration is proposed. A low power three-level VSI is connected in shunt at the power winding with the proposed ARIM drive as discussed above. This VSI compensates the low frequency harmonic currents to achieve sinusoidal motor currents at the motor winding. This VSI acts as a shunt active filter and compensates for the lower order harmonics injected by the LCI. The proposed topologies have LC filters to maintain sinusoidal motor voltages and currents by absorbing the VSI switching frequency components. But the motor terminal voltage oscillates at system resonant frequency due to the presence of LC filters. These resonant components in the terminal voltages are required to be eliminated for smooth terminal voltages and safe load commutation of the thyristors. In this thesis a simple active damping method is proposed to mitigate these issues. The proposed topologies are experimentally verified with an ARIM with 415 V power winding and 220 V excitation winding. The control is carried out on a digital platform having a TMS 320LF 2407A DSP processor and an ALTERA CYCLONE FPGA processor. Results from the prototype experimental drive are presented to show the feasibility and performance of the proposed drive configurations.

This master thesis deals with the modern algorithms of the asynchronous induction machine and permanent magnet induction machine. It focuses at vector control, direct torque control and input-output feedback linearization. It also describes a library creation and its usages in the Matlab – Simulink environment. The final part of this thesis contains an implementation of chosen algorithms on the DSC Freescale 56F800E family.

The main goal of the work is development of the electric car with fuel cells. The whole complex drive will be optimized with respect of minimal consumption of the energy due to achievement of the maximal range of the car. The first part of the work deals with definition of the parameters of the whole drive in dependence of various operating state of the car. The second part describes some acceptable realizations of the traction drive. The most suitable solution was chosen for realization of the small electric car. The third part deals with principle of the minimization of the losses of the asynchronous machine in the wide range of torque and speed. The last part describes final conception and especially technical realization of the car and its parts.

The development of an online method for the early detection of a stator turn insulation deterioration is the objective of the research at hand. A high percentage of motor breakdowns is related to the failure of the stator insulation system. Since most of the stator insulation failures originate in the breakdown of the turn-to-turn insulation, the research in this realm is of great significance. Despite the progress that has been made in the field of stator turn fault detection methods, the most popular and the best known ones are still limited to the detection of solid turn faults. The time span between a solid turn fault and the breakdown of the primary insulation system can be as short as a few seconds. Therefore, it is desirable to develop a method capable of detecting the deterioration of the turn insulation as early as possible and prior to the development of a solid turn fault. The different stresses that cause the aging of the insulation and eventually lead to failure are described as well as the various patterns of an insulation failure. A comprehensive literature survey shows the methods presently used for the monitoring of the turn insulation. Up to now no well-tested and reliable online method that can find the deterioration of the turn insulation is available. The most commonly used turn insulation test is the surge test, which, however, is performed only when the motor is out of service and disconnected from the supply. So far no research at all has been conducted on the application of an online surge test. The research at hand examines the applicability of the surge test to an operating machine. Various topologies of online surge testing are examined with regard to their practicability and their limitations. The most practical configuration is chosen for further analysis, implementation and development. Moreover, practical challenges are presented by the non-idealities of the induction machine like the eccentricity of the rotor and the rotor slotting, and have to be taken into account. Two solutions to eliminate the influence of the rotor position on the surge waveform are presented. Even though the basic concepts of online surge testing can be validated experimentally by a machine with a solid turn fault, it is preferable to use a machine with a deteriorated turn insulation. Therefore, a method, which does not require complex and expensive hardware, to experimentally emulate the turn insulation breakdown is implemented. The concepts at any stage of the work are supported by simulations and experimental results. In addition, the theory of surge testing is further developed by giving new definitions of the test's sensitivity, i.e., the frequency sensitivity and the error area ratio (EAR) sensitivity.

The main focus of the study is the implementation of techniques regarding flux estimation and rotor speed estimation by the use of sensorless closed-loop observers. Within this framework, the information about the mathematical representation of the induction motor, pulse width modulation technique and flux oriented vector control techniques together with speed adaptive flux estimation &ndash / a kind of sensorless closed loop estimation technique- and Kalman filters is given. With the comparison of sensorless closed-loop speed estimation techniques, it has been attempted to identify their superiority and inferiority to each other by the use of simulation models and real-time experiments. In the experiments, the performance of the techniques developed and used in the thesis has been examined under extensively changing speed and load conditions. The real-time experiments have been carried out by the use of TI TMS320F2812 digital signal processor, XILINX XCS2S150E Field Programmable Gate Array (FPGA), control card and the motor drive card Furthermore, Matlab &ldquo / Embedded Target for the TI C2000 DSP&rdquo / and &ldquo / Code Composer Studio&rdquo / software tools have been used. The simulations and experiments conducted in the study have illustrated that it is possible to increase the performance at low speeds at the expense of increased computational burden on the processor. However, in order to control the motor at zero speed, high frequency signal implementation should be used as well as a different electronic hardware.