Overhang Effect Analysis of a Homopolar HTS Synchronous Generator Using 3D Finite Element Method

In this paper, the overhang effect of a homopolar synchronous generator with high-temperature superconducting (HTS) field winding is analyzed. Homopolar topology can be used to implement stationary field winding, which is advantageous for superconducting electrical rotating machine applications that rotate at a relatively high speed. The homopolar machine has an axial-winding radial-flux structure, unlike general heteropolar machines that have a radial-winding radial-flux structure. Therefore, in order to analyze the characteristics of the homopolar machine more accurately, use of 3D finite element method (FEM) should be considered. The overhang of rotor poles in electrical rotating machines can be used to enhance the flux linkage in armature windings and to improve the output power. Therefore, applying the overhang structure in the development of an electrical rotating machine is a method that can further improve the performance of the machines. In this paper, we use 3D FEM to analyze the overhang effect of a homopolar HTS synchronous generator and present the overhang length required to improve the performance of the machine.