A Novel Square-Wave Voltage Injection Based Sensorless Control Method Robust to Single Open-Phase Fault for Dual Three-Phase IPM

The sensorless control for dual three-phase motors (DTMs) under faulty conditions is insufficiently studied in previous research. This article aims to investigate the effects of single open-phase faults (SOFs) on the high-frequency (HF) injection (HFI) based sensorless control for a DTM and presents a new sensorless control method robust to the SOFs. First, the HFI-based sensorless control is introduced into the
αβ
-subspace, where responded HF currents can reflect changes of two sets of three-phase windings simultaneously. Next, an HF fault analysis method is given to simplify the analysis process by making the inductance matrices in the HF models unchanged under healthy and faulty conditions. Besides, an equivalent coordination method is proposed to extend the result under the phase-A SOF to an arbitrary SOF, avoiding repetitive derivation and obtaining a generalized conclusion directly. The SOFs cause the negative sequence components and varying amplitudes in the HF currents, resulting in large rotor position estimation errors. Then, a new rotor position estimation method based on a modified adaptive filter is presented to suppress these effects, which is robust to the SOFs without any fault diagnosis. The validity of the proposed analysis methods and sensorless control methods are all verified on a prototyped DTM.