A Hybrid-Slot Radial-Flux Dual-Stator Permanent-Magnet Machine With Fault-Tolerant Consideration

In this article, a hybrid-slot radial-flux dual-stator permanent-magnet machine (HS-RDPM) with fault-tolerant consideration is presented. On the one hand, the torque density of this structure is improved compared with conventional fault-tolerant permanent-magnet machines (FTPMs). On the other hand, both large torque ripple and weak phase isolation coming from dual stators are optimized. First, radial-flux dual stators with higher torque density are extended to FTPMs innovatively. Second, to decrease torque ripple, dual-layer fractional-slot concentrated winding (DFCW) is used, while optimized rotor and staggered stators are proposed. Finally, the hybrid slots that are composed of deep and narrow notches (DNNs) and large-opening slots are raised to enhance phase isolation; meanwhile, the deflection teeth are proposed to increase slots' utilization. The comparisons between HS-RDPM with conventional and intermediate structures are made. The higher torque density and smaller torque ripple are testified by back-EMFs and torques. The greater phase isolation is proven jointly by flux just with single-phase current, inductance performances, and back-EMFs varieties after a short circuit. In addition, the loss distributions are studied, while the winding temperatures indicate that the security of the machine under a short circuit can be guaranteed if the current is limited. A prototype is manufactured, and the experimental results verify the correctness of simulations.