Reduction of voltage harmonics in three-phase inverters using discrete observers

This paper proposes a simple harmonic feedback strategy for reduction of output voltage harmonics and the removal of any voltage unbalance due to unbalanced linear and non-linear loads in three-phase inverters. The fundamental components of the voltage and current are controlled in dq frame. Two-phase observers have been used for estimating the fundamental αβ components of the inverter voltage and the load current, which in turn helps to segregate the harmonics from the signal. The observer based control strategy, reduction of harmonic distortion and load voltage balancing by the simple harmonic feedback approach has been verified by simulation and experiments.