Diagnosis-Free Fault Tolerant Control for Open Phase Fault in Dual Three-Phase PMSMs via a Unified Control Scheme

Recently, dual three-phase permanent magnet synchronous motors (DTP-PMSMs) have attracted increasing attention owing to their high reliability, high power density, and strong power transmission capability. Regarding remedial strategies under open phase fault (OPF) conditions, conventional fault tolerant control (FTC) methods typically rely on fault diagnosis and controller reconfiguration, which introduce risks of misdiagnosis and increase system complexity. To overcome these limitations, this article proposes a novel unified control framework suitable for both healthy and OPF conditions in a diagnosis-free manner. First, the necessity of fault diagnosis in conventional FTC methods is analyzed, and the underlying principle of the proposed approach is elucidated. Subsequently, a dual branch voltage compensation method is developed by dealing with the fault-induced fundamental components automatically in the z₁z₂-subspace. The required compensation voltage is adaptively generated using the proposed second-order generalized integrator and advanced observer combined structure, enabling high-performance FTC in a simple yet fully closed-loop manner. Finally, experimental results obtained from a practical DTP-PMSM platform validate the effectiveness and superiority of the proposed method.