Improved Finite-State Model Predictive Current Control With Zero-Sequence Current Suppression for OEW-SPMSM Drives

In order to suppress zero-sequence current (ZSC) for open-end winding surfaced permanent magnet synchronous machine (OEW-SPMSM) drives with single dc voltage source, many methods have been employed. Actual solutions imply either proportional-integral-based control or direct torque control cannot present the characteristic of fast dynamic responses and low torque ripples at the same time. Hence, finite-state model predictive current control (FS-MPCC) based on a cost function with ZSC suppression was proposed. To suppress model parameter mismatch, many previous works have proposed related strategies but few work considered zero-sequence parameter disturbances such as zero-sequence inductance, resistance, and rotor flux linkage disturbances. This article improves the ZSC prediction model based on the previous ZSC errors and zero-sequence voltage deviations, and at the same time ZSC is reduced. A comparison between the conventional FS-MPCC and the improved one is carried out in simulation and experiment to verify the effectiveness of the proposed FS-MPCC scheme.

I. Introduction

The open-end winding machine (OEWM) faced a growing interest owing to its high power output, good fault-tolerance, and wide speed range capability [1]. The OEWM is realized by opening the neutral point of the stator winding and connecting each side of it to a power converter. This kind of OEWMs are mainly divided into three parts, namely, OEW-reluctance [1], OEW-induction [2], and OEW-permanent magnet synchronous machines (OEW-PMSMs). Since OEW-surfaced permanent magnet synchronous machines (OEW-SPMSMs) possess the merits of simple control mode and high torque density, they are regarded as a control object in this article [3]. Several control strategies for the OEWM have been proposed and will be reviewed in Section II. Section III describes the OEW-SPMSM drive system specifications. Considering that the main challenges for the application are the suppression of the zero-sequence current (ZSC) and fast dynamic response, Section IV presents a conventional finite-state model predictive current control (FS-MPCC) [25] and [26]. However, the existing FS-MPCC literatures only focused on the reduction of weight factors and calculation. In Section V-A, it can be seen that zero-sequence model parameter can affect the current control performance. Therefore, this article addresses this problem in the red color area of Fig. 1. The contribution is that without employing observers to evaluate a zero-sequence model [30]–[32] or utilizing compensators to eliminate the disturbances cause by zero-sequence model [15]–[17], a novel zero-sequence model based on the previous ZSC and zero-sequence voltage (ZSV), stored in a memory space is proposed. The detailed procedure of the proposed algorithm is described in Section V-B. To validate the effectiveness of the proposed method, the performance of conventional FS-MPCC scheme and proposed FS-MPCC scheme is observed in Sections VI and VII. Finally, the conclusions are derived in Section VIII. Fig. 1.

Diagram of literature review.