Weighting Factor Elimination for Predictive Current Control of Asymmetric Six Phase Induction Motor

Control of multi-phase machines has gained noticeable interest recently both in healthy and faulty operations. Finite control set model predictive control (FCS-MPC) in particular have been proposed to drive multi-phase machines avoiding sophisticated pulse width modulation (PWM) methods. On the other hand, FCS-MPC has some limitations. Weighting factor design in the cost function of FCS-MPC algorithm is one of the widely reported problems which still under investigation. In this paper, the prediction stage of FCS-MPC for asymmetric six-phase induction motor has been reformulated based on the double d-q (2dq) model of the machine. Unlike the reported FCS-MPC algorithm in literature, this will results in four control variables (stator currents in the double stator circuits) which have the same priority. Thus, equal weighting factors could be used in the cost function. It is illustrated that this will automatically reduce the effect of the circulated currents (x-y components) by generating equal reference currents in the corresponding phases of the 2dq representation. The dynamic and steady state performance of the proposed method is demonstrated. Moreover, the proposed method is compared to the FCS-MPC based on voltage space decomposition (VSD) method reported in literature.