Comparison of methods of minimization of cogging torque in wind generators using FE analysis

Abstract

Most small wind turbines use permanent magnet (PM) generators. Small wind turbines are usually self-starting and require very simple controls. The cogging torque, which is generated by the interaction between the magnetized pole of PMs and the salient poles of the armature core, affects the self-start ability and results in undesirable mechanical vibrations and noises. Thus, minimization of cogging torque, which is of utmost importance in improving the operation of small wind turbines is investigated in the present work. In this paper, three design options are investigated to minimize cogging torque: uniformity of air gap, pole width, and skewing. Although the design improvement is intended for small wind turbines it is also applicable to larger wind turbines. A software package based on 2D finite-element analysis is used for the analysis of cogging torque.