Small-variation Linear Model Of The Three-phase Double-fed Induction Motor Uner Synchronous Operation: Stability

The double-fed induction motor (DFIM) is analysed in this paper with regard to stability. Firstly, its characteristic equation is obtained by means of a linear model for small variations, with the stator resistance equal to zero. The range of speeds for which the DFIM/Load system presents stable synchronous operation is obtained by applying the Routh-Hurwitz Criterion to the characteristic equation. Secondly, by employing the equation for the steady-state electromagnetic torque, with a non-zero stator resistance, another range of speeds giving stable synchronous operation is obtained, and confirmed by some experimental results. In order to confirm the stability, some results of the DFIM/Load system simulation and the characteristic equation root-locus are also presented. Copyright © 2005 John Wiley & Sons, Ltd.154325342Holmes, P.G., Elsonbaty, N.A., Cyclo-convertor-excited divided-winding doubly-fed machine as a wind-power converter (1984) IEE Proceedings B - Electric Power Applications, 131, pp. 61-69Krause, P.C., Wasynczuk, O., Sudhoff, S.D., (1995) Analysis of Electric Machinery, , IEEE Press: New York, U.S.AGonzaga, D.P., Burian Jr., Y., Simulation of the 3-phase double-feed induction motor (DFIM): A range of stable synchronous operation (2001) IEEE - Canadian Conference on Electrical and Computer Engineering, pp. 539-544. , Toronto, Canada, Proc. (CD-ROM)Slemon, G.R., (1966) Magnetoelectric Devices: Transducers, Transformers and Machines, , Wiley: New YorkLyon, W.V., (1952) Transient Analysis of Alternating-Current Machinery: An Application of the Method of Symmetrical Components, , Wiley: New YorkDorf, R.C., Bishop, R.H., (1998) Modern Control Systems, 8th Edn., , Addison-Wesley-Longman: Menlo Park, U.S.ANetushil, A., (1978) Theory of Automatic Control, , MIR: Moscow, USSRPrescott, J.C., Raju, B.P., The inherent instability of induction motor under conditions of doubly-supply (1958) IEE Proceedings C, 105, pp. 319-330Nelson, R.H., Lipo, T.A., Krause, P.C., Stability analysis of a symmetrical induction machine (1969) IEEE Transactions on Power Apparatus and Systems, 88, pp. 1710-171