Position Sensorless and Fault-Tolerance Control of Medium Speed SRMs via Self-Correcting Inductance-Based Observer

Accurate rotor position estimation of switched reluctance motors (SRMs) at medium speed is often limited by magnetic-characteristic calculation errors and parameter drifts, such as resistance variation, voltage fluctuation, and current measurement errors. To address these issues, a self-correcting inductance-based state observer for position estimation is proposed. In this method, the effects of resistance, voltage, and current uncertainties are equivalent to inductance disturbances, which are then compensated through closed-loop feedback, effectively suppressing error accumulation and improving robustness against parameter mismatch. In addition, to enhance reliability under open-circuit faults, a fault-tolerant mechanism is developed that identifies faulty phases and prevents erroneous information from being injected into the observer. Experiments on a three-phase 12/8 SRM prototype demonstrate that the proposed method maintains stable and accurate position observation under significant parameter variations and remains effective in open-circuit fault conditions.