Robust State Observer Based Current Sensor Fault Tolerant Control for IPMSM Drives

In this paper, a fault-tolerant control (FTC) mechanism based on a robust state observer for interior permanent magnet synchronous motor (IPMSM) drives is investigated to ensure the IPMSM continues to operate in the event of current sensor faults. In conjunction with field-oriented control (FOC), a robust state observer which integrates both a state observer and a disturbance observer is employed to estimate the three-phase current of the IPMSM. By accurately estimating the current of each phase, a FTC mechanism based on a threshold approach is introduced to detect and isolate faults in the current sensors. An incipient fault model is introduced to simulate gradual sensor degradation, enabling realistic evaluation of the FTC strategy. Moreover, the incipient fault model is injected in the phase-a and phase-b current sensors separately to detect and compensate for current sensor faults by the proposed observer. The proposed FTC system is rigorously analyzed through Lyapunov stability proofs, covering three operational phases: fault-free operation, incipient faults before threshold triggering, and faults after compensation activation. Comprehensive simulations are conducted to validate the performance of the proposed method, demonstrating its ability to maintain stable and efficient motor operation under various fault scenarios. The results indicate that the robust state observer not only improves estimation accuracy but also enhances fault diagnosis reliability, providing a robust solution for faulttolerant IPMSM drives.