Control of self commutation converter in frequency domain with using DFT

This paper proposes an output current control method for a voltage source type self commutated converter in the frequency domain using a discrete Fourier transform (DFT) calculation. It decomposes the three-phase AC voltage and AC current into respective frequency and symmetrical components. The phasor representation of the voltage and the current calculated from the instantaneous values in respective phase is used to control the converter output current. The suitable converter output voltage can be obtained by compensating the unbalanced condition and the harmonics with using the phasor representation expression. The practicability of the proposed control scheme is confirmed through EMTP simulations.