Fault-Tolerant Strategy for Excitation Windings in Hybrid Axial Field Flux-Switching Motor Based on Multi-Vector Model Predictive Current Control

The twisted-stator hybrid axial field flux-switching (TS-HAFFS) motor exhibits the merits of integrated axial design, high power density, and excellent magnetic field control. However, conventional PID controllers often struggle with intricate current loop tuning and limited fault tolerance for single-phase open-circuit faults. To address these issues, this study introduces an excitation fault-tolerant control strategy based on multi-vector model predictive current control. Initially, based on the structural characteristics, a mathematical model of the TS-HAFFS motor is developed in the dq0 coordinate system to effectively decouple the armature and excitation magnetic fields. On this basis, discrete state-space equations are formulated and a multivector current prediction method is adopted. Through the coordinated optimization of armature and excitation voltage vectors, sensorless control of the d-axis, q-axis, and excitation currents is achieved across three degrees of freedom. For conditions involving single-phase open-circuit faults, the proposed strategy overcomes the shortcomings of traditional constant magnetomotive force compensation by introducing an active fault-tolerant mechanism based on excitation magnetic field reconstruction. This mechanism adaptively modifies the excitation current to compensate for the air-gap magnetic field changes, ensuring stable output torque while significantly reducing the armature compensation current. Experimental results verify the effectiveness of the proposed strategy for the TS-HAFFS motor.