Research on High Thrust Force Characteristics With Proper Fractional-Slot Concentrated Winding for a Ultra-Low Speed Tubular PM Linear Machine

In this article, the fractional value characteristics of a tubular permanent magnet linear machine (TPMLM) with fractional-slot concentrated winding for the ultra-low speed direct application are investigated and analyzed, which aims to improve the machine performances such as thrust force capability. Firstly, the thrust force of the TPMLM with the design objectives is derived, which is closely related to the proper fractional values and permanent magnet source of the machine. Secondly, the effects of different fractional value and magnetic source topologies on the thrust force characteristics are analyzed and compared in detail, thereby determining the initial machine model. Then, some key parameters of the TPMLM are designed and optimized, and the performances are evaluated. Finally, the analysis results show that the lower fractional value with 120-slot-140-pole can offer high thrust force and power factor, which can provide a guidance for the same machine design to obtain a high thrust force TPMLM under ultra-low speed applications.