| Abstract |
The stability aspect of induction motor drives with respect to energy optimisation has only been treated superficially in previously published papers. It may, however, be a problem and especially in slow response low-cost drives. In this paper, the stability is analyzed using a standard 2.2 kW squirrel-cage induction motor as a ease. Steady-state calculations show that problems with load disturbances arise by
energy optimization at low speed and low load. It is suggested to run the motor with an air-gab flux slightly above the energy optimal flux level. An experimentally verified dynamic motor model is used to analyze stability with a sudden load change. It is shown that it does not matter whether the load change is slow or fast. This means the stability can always be analyzed with the steady-state model. It is also shown that oscillations are not a problem in small drives. Only in large drives, the series resonance in induction machines may cause problems. If the load is low, energy optimization can increase the series resonance damping and reduce the oscillation problem. |
