Continuous-Control-Set Model Predictive Current Control of Asymmetrical Six- Phase Drives Considering System Nonidealities

Finite-control-set model predictive control (FCS-MPC) of multiphase (
n
-phase,
n
is assumed to be an odd number for simplicity) drives is challenging because of the large number of actual/virtual voltage vectors and the need for current control in (
n
–1)/2 subspaces (or planes; multiplane current control). Any suboptimal design (poor or no current control in some of the (
n
–1)/2 planes) may result in high individual plane current ripples, due to the low reactance. This work therefore investigates continuous-control-set (CCS) MPC for constant switching frequency multiphase motor drives as another alternative. The high-bandwidth CCS-MPC is designed to accurately account for system nonidealities, namely digital control and pulsewidth modulation delays, inverter dead time, and measurement noise. It will be shown that the CCS-MPC has the advantages of full voltage vector space access, regular switching characteristic, and improved cycle-by-cycle tracking control, while maintaining some of the known advantages of the FCS-MPC, e.g., intuitive cost function design, model-based control, and fast dynamics. The proposed control scheme is benchmarked experimentally against the classical, proportional-integral-based, field-oriented control in conjunction with an asymmetrical six-phase induction motor drive.