Brush DC motors with concentrated windings and soft magnetic composites armatures

The armatures of conventional brush DC motors are using windings with interlocked coils elements. With this kind of distributed winding, the axial length of the end-windings is usually very important and their copper volume is large. In this paper, the authors present new structures of brush DC motor armature using a concentrated winding with a plurality of simple coils wound around the same tooth. The copper volume is about 60% lower than in the classical winding armature and the current commutation remains efficient. This kind of structure is well adapted to the use of soft magnetic composite materials for the realization of the magnetic circuit and can be used over a wide power range. The design method and a synthesis of these machines with concentrated winding armatures are presented. A prototype of concentrated winding brush DC motor is compared to a conventional motor used in a typical automotive application. The performance of the new structure in terms of torque to copper volume ratio is much higher than in the case of the classical structure.