Flatness-based voltage-oriented control of three-phase PWM rectifiers

Flatness-based control is applied to the three-phase PWM-rectifier in synchronous reference frame. The DC-link voltage and reactive current are shown to be flat outputs of the full-order system. Two different approaches are presented. At first the DC-link voltage is controlled directly. The second employs inner current loops. Feed forward design based on system flatness is shown and discussed. In many applications the DC-link voltage and reactive current are controlled to constant values. In this case the direct flatness-based approach offers no advantages compared to conventional voltage-oriented PI-control whereas the second approach outperforms it with respect to the obtained control dynamic.