Damping of oscillations in induction machines

A method for damping the oscillations in induction machines, independent of what is exciting them, is proposed and verified. It is shown that, if the stator flux is controlled, the machine appears as if the stator resistance is zero, whereby the damping of the parallel resonance is increased to infinity. It is also shown that, if the torque-producing stator current component is negatively fed back to the stator frequency reference, the stator resistance from the series resonant point of view can be given any value, whereby the damping of the series resonance is variable. To verify the function of the control system described, a series of measurements has been made on a 1.5 kW, four-pole induction motor.<
>