Design analysis of permanent magnet DC motors with differing armature, magnet and yoke lengths

A modified magnetic circuit method and a 2-D finite element procedure are presented for the analysis of DC permanent magnet motors with a differing armature, magnet and yoke lengths including nonlinear material behaviour of steel and permanent magnet. A 12 volt, 120 watts motor is analyzed through these methods and compared with experimental results of a prototype sample. In the case of finite element analysis, commutation effects and short chording of armature winding are treated appropriately, and cogging torque and voltage ripple are predicted.