Open loop stabilization of the rotor angular speed in the induction machine

The stationary conditions for an induction machine (IM) fed by a voltage source containing more than one frequency are studied. Furthermore, it is shown that given one: harmonic input signal, it is possible to stabilize the angular speed of the IM at a beforehand chosen level, by a special choice of frequency and amplitude of a second signal. A generalization to a broader class of feeding signals is provided. The theoretical results suggest that conventional linear time-invariant identification of electrical parameters of the IM become applicable, since using two different symmetrical signals at once will guarantee sufficiently rich excitation for successful identification. Moreover, the method may be used for a new kind of control, where some control algorithm changes the amplitude and/or frequency of the two symmetrical signals.