Automatic armature and field control of d.c. series motors

This paper discusses the limitations of the methods for inherent automatic weak field control of d.c. series motors and comments on a split-field arrangement where the armature and field current of a d.c. series motor can be continuously controlled. The detailed analysis of such an arrangement is presented. The control characteristics of a typical motor are evaluated and a per-unit normalised torque model, which can be used to determine the torque/speed characteristics, is developed with the relative propagation of series to diverted turns as a parameter.