Sensorless Control of Dual Three-Phase Permanent Magnet Synchronous Motors Considering Open-Phase Faults

Sensorless control technology is critical in ac drive systems. Open-phase faults are a common failure mode in motors, making sensorless control under such faults particularly essential. This article proposes a rotor position estimation method based on single-axis high-frequency (HF) injection in the stationary coordinate system for dual three-phase permanent magnet synchronous motor (DTP-PMSM) operating under single or double-phase open-circuit faults. First, position information is extracted in the synchronous rotating coordinate system. A second-order generalized integrator (SOGI) is employed to reconstruct the envelope of the HF current signal, effectively eliminating the issue of DC offset in the HF current components. Second, the inductance variations of the DTP-PMSM under single- or double-phase faults are analyzed, and the resulting rotor position estimation errors are quantified. To address these errors, an angle-compensated phase-locked loop (PLL) is introduced, enabling accurate sensorless control of the DTP-PMSM during open-phase fault conditions. Finally, experimental validation on a DTP-PMSM prototype confirms the effectiveness of the proposed method.