Unified Complex Vector Field-Weakening Control for Induction Motor High-Speed Drives

The voltage closed-loop field-weakening scheme (VCFS) is an effective method to achieve the maximum output torque for induction motor high-speed drives. However, the cross-coupling between the inner current and outer voltage loops leads to system performance deterioration. To address this problem, this article proposed a unified complex vector field-weakening control. First, the inherent coupling problem in VCFS is analyzed based on the double closed-loop structure. On this basis, a complex vector structure is designed to unify the inner current and outer voltage loops, following with a decoupled criterion for controller coefficient selection. Compared with the conventional VCFS, the studied scheme can eliminate the natural complex vector zero in the voltage loop, leading to current ripple and voltage overshoot reduction. The experimental results confirm the effectiveness of the investigated scheme.