Repetitive Observer Design for Torque Ripple Reduction in PMSM Drives

Control strategies aimed at the suppression of periodic disturbance, such as Repetitive Controller (RC) and disturbance observer (DO) have been used in many applications in the past few years. A traditional RC and a conventional DO can be merged into a novel repetitive observer (RO). This paper provides tools to design a RO and proves mathematically that the separation principle used in the DO design is also valid for the RO. The effects of each control parameter on the system performance are also studied and the RO approach is then tested for torque ripple reduction in permanent magnet synchronous machine (PMSM) drives.