Study on Winding Inductances in Stator Surface-Mounted Permanent Magnet Machines

Winding inductance always plays a key role in the electromagnetic performances of stator surface-mounted permanent magnet (SSPM) machines, including their flux-weakening capability, prospective fault current, power factor, current ripple, etc. Generally speaking, winding inductance mainly comprises three components: an air-gap component, a slot-leakage component, and an end-leakage component. In this paper, firstly, the winding pole pairs of SSPM machines are investigated based on the magneto-motive force-permeance model, through which the winding configurations can also be determined. Then, according to the winding configurations, three analytical expressions for each inductance component are derived to evaluate the winding inductance per phase. In addition, finite element analysis (FEA) is employed to verify the effectiveness of the derived analytical expressions. Meanwhile, three prototyped SSPM machines are manufactured, and their winding inductances are measured to further verify the analytical expressions. The measured results agree with both the analytical and FEA results very well.