Synthetic Sensorless Control Scheme for Full-Speed Range of Switched Reluctance Machine Drives with Fault-Tolerant Capability

In this article, a synthetic sensorless control scheme for full-speed range of switched reluctance machine (SRM) drives with phase absence fault-tolerant capability is proposed, which integrates the phase inductance gradient detection and the idle phase inductance threshold comparison. First, in each excitation period, only the demagnetization inductance slope negative-going zero-crossing detection (D-ISNZ) is performed to avoid the erroneous aligned position estimation in the main excitation region. Then, considering the sensitivity of the D-ISNZ method to demagnetization regions, the remedial sensorless control strategy based on single inductance threshold (SIT) is adopted. Also, the synthetic algorithm is developed for the seamless combination between the two sensorless methods. To enhance the reliability of sensorless operation, a fault-tolerant rotor position estimation method considering speed transient and phase deviation compensation is also presented. Furthermore, to ensure stable sensorless starting, a commutation instant direct estimation method based on online determined double inductance thresholds is developed. The proposed sensorless control scheme can achieve robustness operation under various working conditions without any prior knowledge of magnetic characteristics, large storage memory occupations, and intensive computations. Experiments are conducted on a three-phase 12/8 SRM experimental setup to verify the feasibility of the proposed sensorless control scheme.