This research deals with robust demagnetization fault detection for five-phase interior permanent magnet synchronous motors (IPMSM) for the first time. To estimate the rotor flux linkage, two novel integral terminal sliding mode observers are proposed. The first observer utilizes a fractional integral terminal sliding surface and the second one uses a sign integral terminal sliding surface. These observers are designed based on the error of stator d1-q1 currents generated from their measured and estimated values. Practical stability of the proposed observers is demonstrated using Lyapunov stability theory. Comparative simulations validate the feasibility and effectiveness of the proposed ITSM observers on a five-phase IPMSM.
