Sensorless Fault-Tolerant Control Strategy of Six-Phase Induction Machine Based on Harmonic Suppression and Sliding Mode Observer

This paper deduces a unified mathematical model of open-circuit fault of six-phase induction machine, and purposes a fault-tolerence sensorless strategy based on the sliding mode observer(SMO) to estimate the rotor flux and rotor speed. In the proposed control scheme, the sliding mode observer is improved to achieve the rotor speed and rotor flux identification under healthy and arbitrary open circuit faults. The stability of the observer is proved by the Lyapunov function. The quasi proportional resonance (QPR) controller is introduced in the harmonic plane to suppress the harmonic current after the fault. The simulation and experiment results show that the proposed sensorless fault-tolerant control strategy based on sliding mode observer can accurately and effectively identify the rotor speed and rotor flux of the machine under normal and fault conditions.