Direct Torque Control for Zero-Sequence Current Magnetized Memory Machine System with Series-End Winding

This paper proposes a direct torque control (DTC) strategy for zero-sequence current magnetized memory machine (ZSCM-MM) system with series-end winding. A novel integrated voltage vectors (VVs) look-up table is established by the proposed strategy, in which the control of flux, torque and zero-sequence current (ZSC) are considered simultaneously for both normal drive and magnetization operation. During the normal drive operation, both the VVs with and without ZSC component are selected so that the ZSC distortion which is caused by the back electromotive force (EMF) harmonic will be reduced. While in the magnetization operation, only the VVs with ZSC component are selected, which make the magnetization operation as transient as possible. Therefore, both the normal and magnetization control performance will be improved by the proposed DTC strategy. For the validation of the proposed strategy, the mathematical model of the ZSCM-MM is developed and implemented in MATLAB/Simulink. The proposed strategy is verified using simulated results.