Frequency-Adaptive Repetitive Control Based Zero-Sequence Current Elimination in Leg Sharing Post-Fault Operation of OW Machine Drives

Existing zero-sequence current (ZSC) elimination methods have unsatisfactory elimination performance in the post-fault operation (PFO) mode due to unequal dead time effects on the terminals of the open-end winding (OW) machine, resulting in a significant ZSC and unbalanced three-phase currents. This article proposes a new ZSC elimination strategy based on frequency-adaptive repetitive control for OW machine drives to fully eliminate the ZSC during the PFO mode following inverter open circuit faults. To this aim, a frequency-adaptive repetitive controller (FARC) is designed to realize a zero steady-state tracking error of the ZSC loop by eliminating periodic disturbances originated from both inverter and machine sides. In addition, a decoupled space vector modulation technique is developed to produce the required zero-sequence voltage (ZSV) by unequally distributing the ZSC control signal duration time among the duty cycles of the dual inverter legs. Finally, the proposed strategy is verified via simulations and experiments on a dSPACE platform with an OW induction machine.