Speed Control Of DC Motors - DC Motors Speed Control: DC Motors Speed Control - Speed Control Of DC Motors

Learning Objectives :-

Factors Controlling Motor Speed
➣ Speed Control of Shunt Motors
➣ Speed Control of Series Motors
➣ Merits and Demerits of Rheostatic
Control Method
➣ Series-Parallel Control
➣ Electric Braking
➣ Electric Braking of Shunt Motor
➣ Electric Braking of Series Motors
➣ Electronic Speed control Method
for D.C. Motors
➣ Uncontrolled Rectifiers
➣ Controlled Rectifiers
➣ Thyristor Choppers
➣ Thyristor Inverters
➣ Thyristor Speed Control of Sepa-
rately-excited D.C. Motor
➣ Thyristor Speed Control of D.C.
Series Motor
➣ Full-wave Speed Control of a
Shunt Motor
➣ Thyristor Control of a Shunt Motor
➣ Thyristor Speed Control of a Se-
ries D.C. Motor
➣ Necessity of a Starter
➣ Shunt Motor Starter
➣ Three-point Starter
➣ Four-point Starter
➣ Starting and Speed Control of
Series Motors
➣ Grading of Starting Resistance
➣ Shunt Motors
➣ Series Motor Starters
➣ Thyristor Controller Starters

Often we want to control the speed of a DC motor on demand. This intentional change of drive speed is known as speed control of a DC motor.
Speed control of a DC motor is either done manually by the operator or by means of an automatic control device. This is different to speed regulation – where the speed is trying to be maintained (or ‘regulated’) against the natural change in speed due to a change in the load on the shaft.

Speed control of a DC motor is either done manually by the operator or by means of an automatic control device. This is different to speed regulation – where the speed is trying to be maintained (or ‘regulated’) against the natural change in speed due to a change in the load on the shaft

Therefore speed of the 3 types of DC motors – shunt, series and compound – can be controlled by changing the quantities on the right-hand side of the equation above.

Hence the speed can be varied by changing:
The terminal voltage of the armature, V.
The external resistance in armature circuit, Ra.
The flux per pole, φ.