Hybrid Multivector FCS-MPC for Six-Phase Electric Drives

Standard finite control set model predictive controllers (FCS-MPC) suffer from a deteriorated current quality when applied to multiphase drives. This problem has been recently mitigated with the concept of virtual voltage vectors. Its application ensures reduced current harmonics by limiting the x-y voltage injection. An intensive research effort has been done seeking for the best vector combination to provide an optimized performance in FCS-MPC. On one hand, multivector strategies including a null vector refine the effective voltage production with enhanced current quality but the dc-link utilization decreases. On the other hand, the exclusive use of large virtual vectors (LVVs) ensures a higher dc-link utilization at the price of a poorer current quality at low-voltage operation. This article first proposes an extended version of multivector strategies using a zero vector by including a quartet of voltage vectors. The usage of five switching states into the predictive approach (MV5-MPC) improves the current quality but still lacks a suitable utilization of the dc-link voltage. To overcome this limitation, the proposed MV5-MPC is combined with LVV-MPC to provide a hybrid solution that simultaneously achieves a higher current quality and a satisfactory dc-link utilization. Experimental results confirm the effectiveness of the proposal.