State Feedback Control to Damp Output LC Filter Resonance for Field Oriented Control of VSI Fed Induction Motor Drives

To achieve longer life for ac machine drives it is desirable to supply them with pure sinusoidal voltages. This reduces the stress on the windings mechanical structure. This can be accomplished by connecting an additional L-C filter at the terminals of the machine. However such filter will induce resonance effect at the motor terminals due to sidebands of switching frequency in the voltage spectrum. A series resistance to damp out the resonance oscillation can be a solution to this problem. But such a solution is lossy and drastically reduces the overall drive efficiency. In this paper an active damping based on state feedback control technique is employed to damp out the resonance oscillation at the motor terminals. The values of L-C are chosen such that it does not affect the dynamic response nor the vector control loop gains. The proposed technique is verified via simulation and the results are presented.