Improved RC-ESO-Based ADRFC for Torque Ripple Suppression in Symmetrical Six-phase PMSMs with Interturn Short Circuit Faults

For aviation electric propulsion, it is critical that permanent magnet synchronous motors (PMSM) maintain safe operation for a short period after faults. Interturn short circuit faults (ISCF) are serious fault of PMSMs, which can cause a large torque ripple. Active disturbance rejection control (ADRC) is a popular disturbance suppression method for PMSMs. However, conventional ADRC cannot effectively suppress the torque ripple under ISCF. An active disturbance rejection fault-tolerant control with improved repetitive control-based extended state observer (IRC-ESO-ADRFC) is proposed for the first time to suppress torque ripple in symmetrical six-phase PMSMs under ISCF. The IRC-ESO and compensation algorithm are highlighted, which enhance the fault-tolerant control capability of the ADRC architecture and suppress torque ripple with no additional hardware requirement under ISCF. The IRC-ESO is designed based on the fundamental frequency characteristics of the x-axis voltage disturbances under ISCF. Compared to conventional observers, IRC-ESO reduces the observation error of x-axis disturbances under ISCF. The torque ripple compensation algorithm suitable for the ADRC architecture is designed, which is based on the x-axis voltage disturbances observations. The torque ripple generated by short-circuit currents can be significantly suppressed. Comparative experimental results indicate that the ripple coefficient in low and high fault cases decreased by 6.03% and 34.76%, respectively. The effectiveness of the proposed IRC-ESO-ADRFC is validated through both theoretical analysis and experiment.