Suppression of Steady-State Errors in Predictive Current Control of Six-Phase PMSM Drives

Due to their fault-tolerant capabilities, multiphase machines are a good candidate for application in electric drives where the reliability is a key factor. Recently, finite control set model predictive control (FCS-MPC) has been applied to multiphase drives as it provides good dynamic performance, however it cannot provide zero steady-state errors in the controlled variables due to parameter uncertainties and other unmodeled dynamics. In order to suppress these errors, this paper proposes an offset-free predictive current control strategy for six-phase PMSM drives, which uses a disturbance observer (DOB) to estimate the lumped disturbance parameters considered in the prediction model. The performance of the proposed approach is investigated under errors in different parameters, as well as for different deadtime values in the command signals of the inverters.

I. Introduction

Multiphase machines provide additional degrees of freedom, unlike standard three-phase machines, that can be used to improve their performance upon open-phase faults, among other purposes [1]. The improved fault-tolerant capabilities of multiphase machines make them a good candidate for applications where reliability is one the main requirements, such as in offshore wind energy applications [2]. Other advantages of multiphase machines are the reduced current or voltage ratings per phase and lesser torque harmonics [3]. The six-phase machine is the simplest topology among the multiphase machines with multiple sets of three-phase windings and is one of the most addressed configurations in the literature [1].