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T. Wolbank, R. Wöhrnschimmel, J. Machl:
"Slot Geometry - an Important Design Parameter for Zero Speed Sensorless Control of Standard Induction Machines";
Vortrag: International Conference on Power Electronics and Motion Control, EPE-PEMC, Cavtat, Dubrovnik, Kroatia (eingeladen); 09.09.2002 - 11.09.2002; in: "Proceedings 10th international power electronics & motion control conference", CD-ROM (2002), ISBN: 953-184-047-4; S. 1 - 10.

To realise a high dynamic controlled operation of induction machines the flux position has to be estimated during normal operation of the drive. Omitting the shaft sensor leads to a deterioration of the performance at low fundamental frequencies if fundamental wave models of the machine are used. To determine the flux position at zero speed without shaft sensor it is thus necessary to use parasitic non- fundamental wave effects of standard induction machines, such as spatial saturation, slotting or magnetic anisotropy. These effects are not evident in normal operation but can be exploited using high frequencies. Sensorless zero speed schemes thus make use of a high frequency or transient excitation of the machine in addition to the fundamental wave, which are both impressed by the inverter. The machine reaction on this high frequency excitation is then measured and the flux and/or rotor position signal can be estimated by signal processing. However, the shape of the lamination and especially the slot geometry have strong influence on the high frequency behaviour. Before realising a sensorless controlled drive it is thus advantageous to have a look at the design of the machine as not any design is suitable for a specific sensorless control algorithm. Usually either the flux or the rotor position can be extracted by exploiting the two most prominent saliencies caused by saturation and slotting. To investigate the mentioned influence, measurements have been performed and compared on machines designed with different slot geometry. Based on these results, a deeper insight into the spatial distribution of the transient flux linkage and its influence on the control signals is given