Investigation of the End Leakage Flux in Fractional Slot Concentrated-Winding Surface Permanent Magnet Machines.

When the end leakage flux or end leakage inductance cannot be ignored in a permanent magnet (PM) machine (e.g., a PM machine with a short axial length), the analysis of the machine is a time-consuming three-dimensional (3-D) issue. Existing research has made the end leakage inductance no longer to hinder that the performance calculation of fractional slot concentrated-winding surface permanent magnet (FSCWSPM) machines is simplified into a time-saving 2-D issue. However, no such mature research exists for end leakage flux. This paper proposes a novel end leakage flux function that can be used to accurately quantify the end leakage flux of FSCWSPM machines. Then, based on sensitivity research and regression analysis, a parametric model is established to quickly construct the end leakage flux function. Thus, even for FSCWSPM machines with nonnegligible end leakage flux, the results comparable to those from the 3-D finite element method (FEM) can be easily obtained using the proposed end leakage flux function and parametric model to revise the results from 2-D FEM. Moreover, the application of the above function and model is briefly described. Finally, FEM and experimental results are used to verify the calculation precision, adaptability, and timeliness of the proposed methodology.