the present invention relates to armature windings for dc electrical machines , and in particular to those that use electronic commutation and have relatively few slots per pole - pair . the armature windings are particularly well suited for use with rotating dc electrical machines that have a large diameter and a large number of poles such as those that might be directly coupled to the turbine blade assembly of a wind turbine . the armature winding is arranged in relation to the magnetic field generated by a field winding or by permanent magnets such that a number of commutation events during the time taken for the relative movement between the armature and the field system of one pole - pair is much larger than the number of coils per pole - pair .