Virtual-flux-based predictive direct power control of three-phase AC/DC converters

In this paper, a novel predictive direct power control (PDPC) strategy is proposed for three-phase AC/DC converters, which is based on a straightforward regulation of instantaneous active and reactive power. The converter controlled by the proposed strategy realizes operations without line-side voltage sensors by introducing the virtual flux (VF) concept and a grid voltage estimation method based on the instantaneous power. A constant converter switching frequency is achieved by employing the space vector modulation, which simplifies the design of the line filter. Simulation results show that the improvement of power ripple elimination and sinusoidal line currents can be observed in the proposed PDPC at a lower switching frequency. Comparative studies reveal that the steady behaviors of the proposed PDPC are superior to that of the conventional look-up-table DPC (LUTDPC) and PDPC, moreover the transient process of which is more shorter compared with that of the conventional LUTDPC.