Comparison of leakage inductance between fractional slot winding and distributed winding

Due to the large magnetic relevant air gap the leakage inductance is the main inductance in a surface mounted permanent magnet machine. The major components of the leakage inductance are known as the harmonic leakage and the slot leakage inductance. This paper proposes an analytical method to determine those two leakage components for a fractional slot concentrated winding machine (FSCW) with an arbitrary phase number. Further, a comparison to a machine design with distributed winding (DTBW), having the same number of poles and fundamental flux linkage, is done. The comparison is done for FSCW machines with a double layer and single layer winding layout.