There are two electrical elements of a DC motor the field windings and armature.The armature windings are made up of current carrying conductors that terminate at a commutator. DC voltage is applied to the armature windings through carbon brushes which ride on the commutator. In small DC motors, permanent magnets can be used for the stator. However, in large motors used in industrial applications the stator is an electromagnet.Baiscally there’re 4 types of Dc motors.
Permanent magnet motor:-
The permanent magnet motor uses a magnet to supply field flux. Permanent magnet DC motors have excellent starting torque capability with good speed regulation. A disadvantage of permanent magnet DC motors is they are limited to the amount of load they can drive.These motors can be found on low horsepower applications.
Series Motor :-
In a series DC motor the field is connected in series with the armature.The field is wound with a few turns of large wire because it must carry the full armature current.
Additionally the speed of a series motor with no load increases to the point where the motor can become damaged. Some load must always be connected to a series-connected motor.
Shunt motor :-
In a shunt motor the field is connected in parallel (shunt) with the armature windings. The shunt-connected motor offers good speed regulation. The field winding can be separately excited or connected to the same source as the armature.
Compound motors :-
Compound motors have a field connected in series with the armature and a separately excited shunt field. The series field provides better starting torque and the shunt field provides better speed regulation.
However, the series field can cause control problems in variable speed drive applications and is generally not used in four quadrant drives.