DC Motor

A DC motor, or direct current motor, is an electrical motor that uses AC current to transform electrical energy into mechanical energy. There are two types of DC motors based on the construction such as 

1. Self-excited DC Motor 
2. Separately excited  DC Motor
3. Permanent Magnet DC Motor

Similarly, self-excited motors are classified into three types namely 

1. DC series motor
2. DC shunt motor 
3. DC compound motor

DC series motor: The Series motor has a field coil connected in series to the armature winding. For this reason, a relatively higher current flows through the field coils, and it is designed accordingly as mentioned below.

1. The field coils of the DC series motor are wound with relatively fewer turns as the current through the field is its armature current and hence for required MMF less numbers of turns are required.
2. The wire is heavier, as the diameter is considerably increased to provide minimum electrical resistance to the flow of full armature current.
3. Despite the above-mentioned differences, about having fewer coil turns the running of this DC motor remains unaffected, as the current through the field is reasonably high to produce a field strong enough to generate the required amount of torque.

DC shunt motor: A DC shunt motor (also known as a shunt wound DC motor) is a type of self-excited DC motor where the field windings are shunted to or are connected in parallel to the armature winding of the motor. Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage.

DC compound motor: A compound wound DC motor (also known as a DC compound motor) is a type of self-excited motor, and is made up of both series field coils and shunt field coils connected to the armature winding.

• Both the field coils provide for the required amount of magnetic flux, that links with the armature coil and brings about the torque necessary to facilitate rotation at the desired speed.
• Like a shunt wound DC motor is bestowed with an extremely efficient speed regulation characteristic, whereas the DC series motor has high starting torque.
• The compound wound DC motor can further be subdivided into 2 major types based on its field winding connection concerning the armature winding, and they are:
• Long Shunt Compound Wound DC Motor
• Short Shunt Compound Wound DC Motor