Achieving Balanced Magnetic Flux Distribution in Post-Fault Operation With Multi-Layer Winding Configuration

Electric machines with multiple sets of winding configurations are desirable for their high reliability, offering phase redundancy and enabling post-fault operation. Recently, a six-phase electric machine with three sets of two-phase winding configuration has been proposed, which provides both phase and parallel redundancies. Each two-phase winding and its drive can produce constant torque with unique current injection technique to achieve three parallel redundancies required in safety-critical applications such as aerospace and mass transit system. However, during post-fault operation in a triple two-phase winding configuration with a conventional two-layer layout, the separation of phase groups across different slots hinders the reconstruction of the original magnetic flux, resulting in significant flux imbalance. In this paper, a novel triple two-phase winding configuration based on a 4-layer structure is proposed. Post-fault operation is achieved by deactivating the faulty inverter modules and adjusting the angle of the remaining phase flux. Compared to the conventional 2-layer winding configuration, the proposed 4-layer winding configuration ensures a more evenly distributed magnetic flux under post-fault conditions. This approach enhances stability during post-fault operation without potential local saturation of the stator and rotor cores. The effectiveness of the proposed method is validated through simulations based on finite-element analysis.