The main parameters of viscosity, spinning temperature, pressure and winding velocity for coal tar pitch fluid should be rigidly controlled during spinning.

Based on the principle that an equivalent full-pitch, concentrated winding gives the same fundamental MMF as the actual one, the effective number of turns of the equivalent winding is obtained.

Meanwhile, the single pitch fractional-slot winding research was also carried out, calculating the winding factor and analysis the influence of current on winding inductance.