This paper deals with demagnetisation fault detection and tolerance for five-phase interior permanent magnet synchronous motors through a second-order sliding mode controller/ observer. At the beginning, a super twisting flux-linkage observer is proposed to cope with the chattering problem. This observer estimates the flux-linkage through stator estimated currents. Further, a novel second-order terminal sliding mode controller is developed for mechanical speed control in the presence of the detected demagnetisation fault. Finally, various simulations validate the feasibility and effectiveness of the proposed controller/observer for a five-phase interior permanent magnet synchronous motor.
