Speed Control of 3-Phase Induction Motor in Presence of Sommerfeld Effect

This paper considers the dynamics of an unbalanced rotor disk which is supported on a flexible foundation and is driven by a three-phase induction motor (IM). At resonance, the structural vibration amplitudes of the system are high and most of the motor power is spent to excite the structural mode of vibration. If the motor is improperly sized then it may not be possible for it to drive the rotor through this resonance. Even if the motor is sufficiently powerful, it first approaches the natural frequency and then suddenly jumps to a much higher value. This classic phenomenon is called the Sommerfeld effect. IM control laws often neglect this phenomenon. We develop a controller for such situation. The source-structure interaction involving the power transfer mechanism is modeled through bond graph and simulation results are presented.