AC loss study of a 300 kW fully HTS synchronous wind generator considering winding heads

Abstract As a high-power-density and lightweight solution, fully high-temperature superconducting (HTS) synchronous generators have attracted extensive research interest driven by the rapid expansion of the wind energy sector. Within the SupraGenSys2 project, a 300 kW fully HTS synchronous generator has been designed as a scaled demonstrator targeting a 10 MW HTS wind generator. For the first time, three-dimensional (3D) full-scale models are developed to quantify AC losses in the winding heads of armature and field windings in this generator using the T-A homogenization method. The simulation method is experimentally validated with a double pancake coil (DPC). Corresponding two-dimensional (2D) models are built for comparison. The influence of AC ripple current on the AC loss of the armature winding is also investigated. For a given armature coil in the 3D model, the AC loss in the winding head is 17.21% and 6.32% lower than that in the two straight sections, which have an axial length equal to the effective core length of the generator. Regarding a specific field coil, the AC loss in the winding head is significantly lower than that of the two straight sections within the first electrical cycle in the 3D model. The total loss of the field coil is dominated by the dynamic loss. Compared with the 2D model, the magnetic flux lines are more perpendicular to the coil surface in the 3D model due to the radial magnetic field component induced by the closed-loop 3D coil. With the superposition of AC ripple at 500 Hz and 1 kHz onto the sinusoidal armature coil current, the AC loss increase in the armature coil remains minor when the ripple amplitude is 1 A. However, a substantial loss increase is observed when the ripple amplitude rises to 5% and 10% of the rated armature coil current amplitude at 1 kHz.