Evaluation of calculation methods and the effect of end-winding inductance on the performance of non overlap winding PM machines

A common practice in the design and evaluation of non overlap winding PM machines is to ignore the end-winding inductance. In this paper it is shown that the end-winding inductance has a significant effect on the short-circuit performance of the non overlap winding PM machine, which is important for amongst others, wind generator applications. A number of proposed calculation methods for the per phase end-winding inductance of the machine are evaluated and compared. Also a new simple analytical calculation method that takes the effect of the iron core into account by means of mirror-images, is proposed. This method is shown to give a relatively good prediction of the end-winding inductance compared to 3D finite element results. The study is conducted on a number of different direct drive non overlap winding PM wind generators.