Virtual-Stator Loss Model for Synchronous Generators With Fractional-Slot Winding

In synchronous generators, the end-region field can cause additional losses at clamping structures and stator end core. It can be a computational challenge to solve the end-region field of synchronous generators featuring fractional-slot winding. With a minor modification of the number of stator slots, the winding scheme can be changed to the integral slot and, consequently, a virtual stator is derived. The model size of a three-dimensional (3D) Virtual-stator Loss Model (VLM) is much smaller than the Real-stator Loss Model (RLM), and the computational burden is substantially alleviated. This paper delves into the theory underpinning VLM and its practical implementation. From the perspective of two-dimensional (2D) analysis, 2D VLM demonstrates close results in field analysis and loss computation when compared to 2D RLM, indicating the potential of the 3D VLM in accurately computing end-region losses. The 3D VLM is used to compute the end-region losses at different operating points. It concludes that the 3D VLM can keep the essential nature of the loss-producing mechanism while dramatically mitigating the computation hurdles. Lab tests at a 100 kVA salient-pole synchronous generator prove that the investigation approach employed in the paper is trustworthy.