In what two ways can the speed of a dc motor be varied?

speed of a dc motor can be varied by mainly two methods:-

1)field control method

2)armature control method

further ,

field control method can be divided in 3 parts:-

1)field rhestat control method---speed variation is acomplished by means of a variable resistance inserted in series with shunt field

2)reluctance control method---by changing the reluctance of magnetic circuit by choosing right material..

3) field voltage control method-requires variable field voltage supply.

and armature control method can be divided in 3 parts :-

1)armature resistance control---variable resisitance connected in series with armature

2)shunted armature control.

3)armature voltage control.

------------mrityunjay pandey

(kiit university ,btech 2nd year)