A Novel Virtual Voltage Vector Based-SVM Strategy for Zero-Sequence Current Excited Memory Machine With Series-End Winding

Zero-sequence current excited memory machine (ZSCE-MM) employs transient zero-sequence current (ZSC) to change the magnetization state of low-coercive-force (LCF) magnet. Hence, the torque density improvement and flexible flux regulation can be realized simultaneously without requiring additional magnetizing winding as well as associate current controller. However, this advantage of ZSCE-MM cannot be fully utilized through the traditional virtual voltage vector based-space vector modulation (V³-SVM) strategy, which constrains the ZSC generation ability. Consequently, a novel V³-SVM based on virtual voltage vector reconstitution technology with high dc-link voltage utilization is proposed for ZSCE-MM drive, while the simple identification progress is also preserved. Since the virtual voltage vector is expanded from the 0-axis to 3-D space, the linear modulation region in 3-D space can be enlarged. The proposed novel V³-SVM strategy can generate a higher amplitude of ZSC under the on-load situation, which means a wider flux regulation region can be achieved which is beneficial for global efficiency improvement of ZSCE-MM. The effectiveness of proposed novel V³-SVM strategy is validated by both simulation and experimental results.