Multi-phase Predictive Control Using Two Virtual-Voltage-vector Constellations

In the field of variable speed electric drives, the predictive method based on virtual voltage vectors has recently appeared. This method allows to reduce the voltage contribution in the x-y subspace, in which no torque is produced, but losses. This not only limits the losses but also reduces the tuning complexity of the predictive controller. The virtual voltage vectors are obtained by combining tension vectors belonging to different small, medium and large crowns in addition to the null vectors. In a typical application, first the crown(s) to be used are chosen and then the virtual vectors are developed. The predictive controller uses in each sampling period the most suitable virtual vector. In this work we propose the use of several sets of virtual vectors coming from different combinations of crowns. For each operating point of the electric drive, the set that provides the best values of a certain goodness criterion is used. The proposed method is experimentally validated using a six-phase induction machine.