Sensorless Fault-Tolerant Control via High-Frequency Signal Injection for Aerospace FTPMSM Drives with Phase Open- and Short-Circuit Faults

The high-frequency (HF) signal injection methods have been widely used for the low-speed sensorless control of permanent magnet motors under the vector control framework. However, for the fault-tolerant permanent magnet synchronous motor (FTPMSM) system under fault conditions, the fault-tolerant control is usually based on independent control of each phase current, rather than the vector control, which prevents the existing sensorless control from being directly applied. To cope with this issue, this article proposes a novel sensorless control by HF signal injection in any nonfault two-phase windings for the FTPMSM system with no coordinate transformation, which can ensure the low- and zero-speed sensorless control performance both in fault-free and fault-tolerant operation conditions. This sensorless control scheme is based on an independent control framework of each phase current, which consists of the real-time inductance observer, the nonorthogonal phase-locked loop (NPLL), the notch filter, and the polarity discrimination of the magnet pole. The real-time inductance observer is proposed to estimate the differential mode inductances of two nonfault phases. The NPLL is proposed to achieve the rotor position and speed estimation based on the obtained two-phase inductances. To enhance the sensorless control performance, a new notch filter is proposed to filter out the injected HF response component in phase current. The proposed sensorless FTPMSM system has preeminent low-speed control performance and robustness in the nonfault and fault-tolerant operation process, which is also verified via experiments on a six-phase FTPMSM platform.