Disturbance-Observer-Based Sliding Mode Speed Control for Variable Flux Memory Machines Considering Magnetization State Manipulations

Variable flux memory machine (VFMM) requires injecting the d-axis current pulse to manipulate its magnetization state (MS) for permanent magnet (PM) flux linkage regulation, during which large speed fluctuations are usually caused. Therefore, this article proposes a disturbance-observer-based sliding mode speed control for VFMM drive systems to deal with their unique MS manipulation disturbances. A novel sliding mode speed controller (N-SMSC) considering both the normal operation and MS manipulation modes of VFMM is constructed to achieve better dynamic performance. Besides, the lumped disturbance, particularly the drastically changed MS manipulation disturbance, is estimated by a proposed new sliding mode torque observer (N-SMTO) combining with the model compensation and then compensated into the speed controller. Finally, the effectiveness and feasibility of the proposed method are validated through experiments.