Permanent-magnet machines with powdered iron cores and prepressed windings

This paper presents a permanent-magnet servomotor, built with a powdered iron stator, which has been designed to take full advantage of the properties of the material. There are a number of important design features which are not possible with laminated cores. For example, the core back is axially extended over the end windings, the armature core components are subdivided and preformed stator coils are used. The coils are prepressed to form a solid component with an exceptionally high fill factor (78%). The prototype offers far superior performance to a conventionally laminated commercial machine, manufactured in the same frame.