Investigation and improvement of flux density harmonic content in electrical machines with fractional slot tooth concentrated windings

The fractional slots tooth concentrated windings are characterized by high number of a magnetic field spatial harmonics. It leads to undesirable effects on an electrical machine, such as eddy current loss in the rotor, localized core saturation, vibration and noises. This paper compares three electrical machines with different fractional slots tooth concentrated windings but designed for the same power with the same active volume. The compared machines' performances and harmonic content of the created magnetic field are presented. In particular, the winding which allows to improve the harmonic content of the magnetic field with the improved topology is presented.