The most serious and recent competitor to the standard field oriented control for induction motors (IM) is the finite control set model predictive control (FCS-MPC). Nevertheless, the extension to multiphase drives faces the impossibility to simultaneously regulate the flux/torque and the secondary current components (typically termed x - y in the literature). The application of a single switching state during the whole sampling period inevitably implies the appearance of x - y voltage/currents that increase the system losses and deteriorate the power quality. These circulating currents become intolerably high as per the unit x - y impedance and the switching frequency diminish. Aiming to overcome this limitation, this work suggests the integration of virtual voltage vectors (VVs) into the FCS-MPC structure. The VVs ensure null x - y voltages on average during the sampling period and the MPC approach selects the most suitable VV to fulfill the flux/torque requirements. The experimental results for a six-phase case study compare the standard FCS-MPC with the suggested method, confirming that the VV-based MPC maintains the flux/torque regulation and successfully improves the power quality and efficiency.

Finite-control set model predictive control (FCS-MPC) has been successfully applied to three-phase electric drives and has proven to bring fast dynamics and high flexibility. The extension of model predictive control (MPC) to regulate machines with more than three phases (i.e. multiphase) presents however additional challenges. Leaving aside the higher computational requirements, the appearance of additional degrees of freedom requires a simultaneous current tracking in different subspaces. Hence, the accuracy in the fundamental plane needs to be accomplished with no simultaneous excitement of the secondary planes in order to avoid unacceptable inefficiencies. This work jointly tackles the performance improvement of fundamental and secondary planes following a two-step procedure: individual virtual voltage vectors (VVs) firstly ensure low circulating currents and the optimal combination of two VVs provides enhanced current tracking in the fundamental plane. Comparative experimental results confirm the satisfactory performance of the proposed strategy.

Model predictive control (MPC) has been recently suggested as an interesting alternative for the regulation of multiphase electric drives because it easily exploits the inherent advantages of multiphase machines. However, standard MPC applies a single switching state during the whole sampling period, inevitably leading to an undesired x-y voltage production. Consequently, its performance can be highly degraded when the stator leakage inductance is low. This shortcoming has been however mitigated in recent works with the implementation of virtual/synthetic voltage vectors (VVs) in MPC strategies. Their implementation reduces the phase current harmonic distortion since the average x-y voltage production becomes null. Nevertheless, VVs have a static nature because they are generally estimated offline, and this implies that the flux/torque regulation is suboptimal. Moreover, these static VVs also present some limitations from the point of view of the DC-link voltage exploitation. Based on these previous limitations, this work proposes the implementation of dynamic virtual voltage vectors (DVVs), where VVs are created online within the MPC strategy. This new concept provides an online optimization of the output voltage production depending on the operating point, resulting in an enhanced flux/torque regulation and a better use of the DC-link voltage. Experimental results have been employed to assess the goodness of the proposed MPC based on DVVs.

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.

Multiphase machines offer some interesting features to develop more-competitive electric drives. However, the control complexity increases due to the higher number of freedom degrees. Specifically, the regulation of secondary currents becomes critical to avoid an unacceptable harmonic distortion of phase currents. In this regard, standard finite-control-set model predictive control (FCS-MPC) is characterized by a limited capability to provide a suitable current quality, since a single switching state is applied per control cycle. In order to reduce the current harmonic content and retain the well-known FCS-MPC advantages, the use of a multi-vector approach has been recently explored in the field of multiphase electric drives. Following this trend, this work develops a simplified FCS-MPC version with a new generation of virtual voltage vectors (VV) that are used as control actions. The switching states that form the proposed VV provide null average $x-y$ voltages and reduced instantaneous injection of these secondary components. The capability of the suggested VV-based FCS-MPC strategy to mitigate the $x$ – $y$ injection is experimentally tested and compared to field-oriented control (FOC) using carrier-based pulse width modulation (CB-PWM) and diverse FCS-MPC schemes.