How to Manage DC Motor Speed Control?

For a DC Motor, the speed control operation means that there is an intentional change of drive speed to a desired value at which a specific work has to be performed.

It is important to note that speed control in DC motor is different from regular speed regulation, where a natural difference in speed is noticed because of the change in load of the shaft. For DC motor speed control, the speed can be managed either manually by the operator or through automatic control device.

Speed control is among beneficial features of a DC motor. Speed control of a DC motor can be categorized into two; one is armature control methods and second is field control methods.

In an Armature resistance control method, controlling resistance is directly connected in series with the supply to the motor. This is an economical method of speed management while maintaining constant torque throughout.

In case of power loss in the control resistance of a DC motor, it can be overlooked as this speed control method is applied for a considerable time to moderate the speed under light load condition.

The Armature speed control method is applied to regular speed for DC motor driving cranes, hoists, trains etc. The second method is the shunted armature control. In this speed regulation method, a mix of a rheostat shunting the armature and a rheostat in series with the armature is involved.

In comparison to Armature resistance control method, it is not a feasible solution when it comes to DC motor speed control. This is due to power losses in speed controlling resistances.

Another method of DC motor speed regulation is Armature terminal voltage control. Speed in a DC motor can be controlled by supplying power from an individual variable voltage supply. This is a highly expensive DC motor speed control methods, therefore rarely used.

There are several other methods to manage DC motor speed control which include field diverter method, tapped field control, and more.