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T. Wolbank, R. Wöhrnschimmel:
"Influence of Rotor Design on Sensorless Control for Induction Motors";
Poster: IEEE + EPE 'Conference on Power Electronics and Applications' (EPE), Graz, Austria; 2001-08-27 - 2001-08-29; in: "Proceedings 9th European Conference on Power electronics and Applications", (2001), ISBN: 90-75815-06-9; 1 - 11.

Sensorless, field oriented control of standard induction motors at and near zero frequency can only be achieved by exploiting inherent saliencies. The two most prominent saliencies, which are usually exploited are caused by saturation and slotting, thus enable the detection of the main flux and the rotor position. The influence of these saliencies is not evident in normal operation of the drive. However, it can be detected with a high frequency or transient excitation caused by the inverter. Therefore, the high-frequency response is evaluated to obtain the control signal.
As the interaction of all saliencies may lead to a deterioration of the performance of the sensorless control algorithm in specific points of operation it is advantageous to exploit only one saliency trying to compensate the influence of the others. To facilitate this separation, different machine design parameters can be adjusted reference to the saliency which has to be suppressed.
This paper is focused on the influence of different rotor design parameters on the sensorless control signal. Measurements were performed reference to sensorless control and to the spatial distribution of the transient flux change measured with test coils placed at different areas of the machines.
To achieve this, differently designed machines have been manufactured, only influencing the saliencies present in standard induction machines.
In addition results obtained from simulations covering transient hysteresis effects are presented and compared to give a further insight into the transient electrical behaviour of induction machines.
The sensorless control scheme applied in this paper is based on a transient excitation of the machine. It detects local differences in the stator impedance of the machine caused by spatial saliencies by evaluating the transient current change due to voltage pulses applied to the terminals of the machine.