Steigerung des Wirkungsgrads und der Ausnutzung von Norm-Asynchronmotoren mit Kurzschlusskäfig

Die allgemeine Energiesituation am Ende des 20. Jahrhunderts zwingt die Menschheit zum bewussteren Umgang mit der Energie. Weiterhin sorgt ein weltweites Umdenken in der Umweltpolitik zu einer Verschärfung der Energiesituation und (besonders in Deutschland) zu einem verstärkten Einsatz regenerativer Energiequellen, was u. A. den Strompreis erheblich ansteigen lässt. In diesem Zusammen-hang wird auch die Reduzierung des Energieverbrauchs elektrischer Verbraucher angestrebt und im Energiekonzept der Bundesregierung von 2010verankert. In der Antriebstechnik führt das zu immer strengeren neuen Wirkungsgradklassen (z.B. IE3 und IE4, IE5 in Diskussion), in die die Antriebe eingestuft werden. Motoren, die einen hohen Energieverbrauch haben und somit einen niedrigen Wir-kungsgrad (

The energy situation at the end of the 20th century forces mankind to use their energy resources more efficiently. Furthermore a worldwide rethinking about the ecological policy intensifies the discussion on the energy situation and leads (especially in Germany) to a stronger use of renewable energy sources. This increases the costs for electric energy. Therefore the German government decided to develop concepts to reduce the energy consumption, which was summarized in the energy concept in the year 2010. In the area of drive technology, this results in new and tighter efficiency classes (e.g. IE3 and IE4, IE5 under consideration), in which the machines are classified. Motors that have a big amount of losses and therefore a low efficiency (< IE2) should vanish stepwise from the market. Due to the lower robustness and the strongly increasing price of rare earth magnet materials permanent-magnet synchronous machines are at the moment no economical alternative for industrial applications, although the efficiency is higher compared to induction machines. For the design of high efficient squirrel cage induction machines very precise calculation models are necessary. In this thesis, models for the electro-magnetic design of squirrel cage induction machines, which take into account the influence of double-sided slotting, the production process and iron satura-tion on the machine performance are introduced. The focus is on the power balance of the motors for different load points. Especially the prediction of the additional losses Pzus is a challenging task and is therefore regarded more in detail. With investigations on three 4-pole machines with the frame sizes of 80 mm, 100 mm and 160 mm (machine data in Appendix A) and rated output power values of PN = 750 W, 2200 W and 9200 W the calculation models are tested, optimised and validated with the help of FEM-calculations (FLUX2D, ANSYS) and measurement results. The results proof that the introduced models for the calculation of the electro-magnetic parameters, as well as the thermal and the acoustic behavior, deliver satisfying and reliable results. The gained experiences are used to improve the calculation program KLASYS, that was developed at the Institute for Electrical Energy Conversion.
The calculation models were used to redesign a production line with frame size 160 mm with motors of different output power values and efficiency classes to reach improved efficiency of the motors. The predictive calculations of the redesigned motors were checked with measurement results of prototype motors and show very good accordance. The results of this thesis suggest that the desired machine performance, which considers all proposed boundary conditions, cannot be reached. To reduce parasitic harmonic effects as e.g. additional losses or harmonic torques a star-polygon poly-phase winding for an induction machine was investigated. Due to the series connection of a outer star and inner delta connection of the stator coils with different number of turns, the ampere turns of a six phase winding with 30°el phase shifted currents is approximated. The comparison of a series motor with frame size 180 mm (AH180 with PN = 15 kW) with a prototype motor PT180 of the same total machine volume and the same iron stack geometry, but equipped with a star-polygon poly-phase winding, shows an increase of efficiency for motor P180, compared to motor AH180, by ca. 1 % and at the same time a reduction of harmonic torques and acoustic noise emission.