Robust Sensorless Strategy for Dual Three-Phase PMSM by the Virtual EMF Under Single Open-Phase/Open-Switch Fault

Open-circuit faults increase estimated rotor position errors in conventional sensorless control methods of dual three-phase permanent magnet synchronous motors due to the distortions of observed electromotive forces (EMFs) in the αβ-subspace. To address this issue, a virtual EMF method is proposed to analyze the effects of open-circuit faults, including all types of single open-phase/open-switch faults, on the observed EMFs. The analysis results indicate that the distortions of observed EMFs caused by open-circuit faults appear in both the αβ- and
xy
-subspaces with the same components. Based on these findings, a novel rotor position estimation method with a fault diagnosis is designed to eliminate the EMF distortions by reconstructing the observed EMFs of two subspaces. Thanks to the specialized reconstruction, the fault diagnosis only needs to detect the faults associated with which set of three-phase winding rather than which phase, resulting in fewer diagnosis states and further leading to a fast diagnostic speed. Experiments validate that the proposed method can accurately estimate the rotor position under various open-circuit faults.