The independent excitation DC motor is the motor in which the field coils are connected independent of the armature. They are also made by several turns of fine conductor, where the gauge will vary according to the power of the motor and will be suitable for the field that one wants to obtain.
Thus we have full control of the speed and torque, which will be constant for any load value and this will be better utilized with the control of both the field voltage and current as well as the armature current.
The composite DC motor has field coils consisting of two windings attached at the poles where the coils are attached. One of these windings is conductive, relatively thick and is connected in series with the armature and the other is a thin conductor, which is connected in parallel with the armature.
This type of motor has characteristics similar to the motor in series and to the motor in parallel, because its starting is vigorous and its speed is stable in any load. The compound motors may be of the additional or differential type and what determines this difference is the variation of the configuration of the internal connections.