Model predictive current controller for four-leg converters under unbalanced conditions

In this paper, current predictive controller is proposed for grid connected 4-leg VSCs which generates control signals without voltage reference calculation. This direct control of switch control signals is based on geometrical approach where the predicted and reference currents are projected in a 3-D space. To reach the reference, an association of three active control and two null vectors is used. This association constitutes a control profile. The profile projections divide the action zone of the converter into 24 different volumes. The appropriate control profile is selected according to a criterion optimization. For this task, geometrical properties of current projections are used.