Fault Diagnosis and Fault-Tolerant Control for Dual Permanent Magnet Synchronous Motor With Demagnetization Fault

In this paper, a fault diagnosis and fault tolerant control scheme is proposed for dual permanent magnet synchronous motor (Dual-PMSM) system with partial demagnetization fault. The proposed approach is specifically proposed for the Dual-PMSM architecture to solve the problem of performance degradation in the healthy motor caused by fault propagation through the synchronous control loop. In contrast to the idealized scenario of uniform demagnetization, partial demagnetization fault refers to demagnetization of only one or a subset of magnets within PMSM. The partial demagnetization fault is usually caused by local overheating or external shock, which are more challenging and difficult to be detected than uniform demagnetization. When the demagnetization fault occurs, it not only affects the speed of the faulty motor but also has a significant influence on the healthy motor due to the presence of synchronous control. The dual surface-mounted PMSM system model is introduced firstly. Then, in the presence of disturbance, an improved sliding mode function with smoother switching within the boundary layer is introduced to suppress chattering, and based on this function, an augmented sliding mode observer (SMO) is designed to estimate the system state, disturbances, and potential demagnetization fault. After obtaining the detailed system information, in the speed synchronous controller design, the controllers of both motors are designed to compensate the demagnetization fault. Subsequently, linear quadratic regulator (LQR) algorithm is used to optimize the Dual-PMSM speed synchronization error. When fault occurs, the speed error can be reduced as much as possible to ensure the system performance. Finally, experimental results demonstrate the feasibility of the proposed algorithm.