A Flux-Vector Direct Torque Control Strategy Based on d,q-Axis Flux Closed-Loop Regulation for Permanent Magnet Synchronous Motor Drives

Abstract

In space-vector-modulation-based flux-linkage-loop-free direct torque control (SVM-FLLF-DTC) for permanent magnet synchronous motor (PMSM) drives, the open-loop d-axis voltage control causes an inherent magnetization effect, and the conventional single-axis flux-linkage limiting strategy entails a risk of positive-feedback runaway. To address these issues, this paper proposes a flux-vector direct torque control (FV-DTC) strategy. The method replaces the torque inner loop and the current regulation loops with two independent proportional controllers that directly regulate the d- and q-axis stator flux-linkage components, and employs a three-scenario flux-reference generation scheme to adaptively determine the flux-linkage references. This scheme eliminates the magnetization effect by clamping the d-axis flux linkage at the permanent magnet value during normal operation, and breaks the positive-feedback runaway by imposing a hard constraint on the q-axis flux-linkage reference when necessary. Experimental results on a rapid control prototype (RCP) platform validate the effectiveness of the proposed strategy.