DC-Link Utilization Enhanced Implicit Model Predictive Control for Dual Three-Phase PMSMs

The model predictive control (MPC) with implicit space vector modulation (SVM) techniques is facing a challenge in application to dual-three-phase (DTP) electric drive systems, namely, that the optimal switching sequence (OSS) has to be selected within all the possible candidates exhaustively. To reduce the severe computational burden, these algorithms use the unconstrained optimal voltage reference to locate the modulation sector and thus acquire the OSS. However, the constrained optimal voltage reference is outside the located sector on occasion. As a result, the non-optimal switching sequence (SS) is selected and leads to the weaken utilization of dc-link voltage. This article proposes a fast searching method that is dependent on the geometrical and analytical knowledge to find the OSS, where the unconstrained optimal voltage reference is projected onto the modulation boundaries to approximate the location of the constrained optimal voltage reference. The proposed method enhances the dc-link utilization which contributes to the good harmonic suppression at the linear modulation and torque reference tracking at the overmodulation. On the other hand, the computational burden is significantly reduced, so that the category of MPC with implicit SVM schemes is easy to implement on industrial digital processors. The experimental results are given to verify the improvement of the method in this article.