A Two-Terminal Hybrid Parallel Connection Method for Simultaneously Enhancing the Output Performance and Fault Tolerance of Dual Three-Phase Machines

Electric machines have long been a focal point for achieving both high output performance and robust fault tolerance, despite the inherent conflict between these two aspects in most scenarios. This article proposes a winding connection method called the two-terminal hybrid parallel connection method (THPCM). THPCM offers lower space harmonics of armature magnetomotive force (MMF) and a higher fundamental amplitude compared with conventional winding connection methods. It also demonstrates enhanced fault tolerance under adverse conditions. THPCM divides the winding into three parts: the first is like traditional machines, while the second and third create parallel paths with star-delta connections. The principles behind harmonic elimination in this method are deduced, and the mechanisms for improving output performance and fault tolerance are explained. Subsequently, the armature MMF distribution and output performance of traditional three-phase, star-delta, dual three-phase, and THPCM machines under normal operating conditions are compared by finite element method. Additionally, the fault tolerance of machines under open-circuit faults and interturn short-circuit faults is investigated. Results confirm the good output performance and fault tolerance of THPCM. Finally, a prototype THPCM machine is manufactured and tested, with experimental results closely aligning with simulation outcomes, validating the reliability of the theoretical and simulation analyses.