T.M. Wolbank, R. Woehrnschimmel, J.L. Machl, and H. Hauser (Austria)
ac machines, sensorless control, lamination design
Saliencies in the high frequency or transient electrical behavior of AC machines can be exploited by zero speed sensorless control schemes using a high frequency or transient signal in addition to the fundamental wave excitation impressed by the inverter and by measuring the reaction of the machine. Thus the flux and/or rotor position signal can be extracted. There is however, a heavy dependence of the lamination design on the performance of the control. This investigation is focused on the fundamental wave saturation at different places of the lamination and its influence on the asymmetries emerging at a transient excitation. The results are based on measurements made with three different induction machines, all of the same type of production. One with standard lamination design and an evenly distribution of the level of saturation along the flux paths. The other two specially designed to obtain specific saturation zones in the regions of the teeth and the yoke respectively. The resulting control signal is separated into different components originating from the different flux paths which spatially saturate various areas of the lamination. A transient representation it given in the complex current response plane where a phasor is associated to each component. The analysis and measurement results show that it is possible to use the strong influence of the lamination design to perform an optimization of the design reference to sensorless control applications.
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