The effect of iron powders on the utilization of permanent magnet materials in advanced motors

The properties that may be obtained in an iron powder/epoxy resin compact are discussed, and the application of this material as wedges in the armature of an axial-field d.c. machine are described. The effect of the wedge parameters on the design and performance of the machine has been studied, particularly considering the non-uniform flux density across the active diameter in a wedge. Using an electric vehicle traction motor as an example, it is shown that considerable savings in permanent magnet material are achieved by introducing wedges into the previously ironless armature, being as high as 74% with SmCo5magnets.