Speed control of DC motor, dc motor speed control

In this article we will learn about how to speed control of dc motor. we will also discuss different type dc motor speed control , different method of speed control of dc motor.

Speed  control of   DC   motor 

speed control of DC series motor

Dc series motor speed can varies by changes in supply voltage and armature current

N = Back EMF / Flux

Back EMF =  Supply voltage(V) - Armature voltage drop 

N = Supply voltage - Armature voltage drop / Flux


from above equation Speed(N) is inversely  proportional to Armature current and directly proportional to supply voltage .  we can also  change of speed by flux control because flux is inversely proportional to speed from above equation.

Methods which are used to vary in speed

1. Field diverter method

2. Armature diverter method

3. Field tapped control method 

4. paralleling field winding method

Speed control of dc motor, speed control of dc series motor ,speed control of dc shunt motor

1. Field diverter method

it is common type of speed control of dc motor.
In this method a variable resistance (which called divert er)is connect across(parallel) the series field winding  . In this type some series field current  flow through diverter and less current flow through field winding which cause flux become less and  motor will increase.


2. Armature diverter method

Speed control of dc motor, speed control of dc series motor ,speed control of dc shunt motor
Add caption
 it is simple way of speed control of dc motor.
In this method a variable resistance (diverter) connect  across(parallel) the armature.
In this method supply current will increase and flux will also increase from these cause motor speed become less. By this method we can reduced the speed of motor.

Speed control of dc motor, speed control of dc series motor ,speed control of dc shunt motor

3. Field tapped control method





In this method provide tapping on field winding of DC series motor. this type according to no. of turn of field winding we can varies the speed of motor by change of taping position.


4. Paralleling field winding method 

In this method field coils connect in parallel in each other which cause supply current divided in two part . from this method motor speed will increase
Speed control of dc motor, speed control of dc series motor ,speed control of dc shunt motor By using this method we can increase speed of DC series motor






Speed control  of DC (shunt) motor


Back EMF = Flux * Z*N*P/60A 

where Z is no. of conductor

N speed of motor in RPM

P is no. of poles in motor

A is no. of parallel path in Armature

N is directly proportional to EMF and inversely proportional to flux

Back EMF = V -  Armature voltage drop 

DC shunt motor speed can change by use of different method

A. Flux/Pole control

B. Armature current or Armature Resistance

C. Control of Supply voltage
Speed control of dc motor, speed control of dc series motor ,speed control of dc shunt motor

A. Flux/ Pole method


N is inversely proportional to flux
so we can change the speed of motor by change in flux . In this method a rheostats (Resistance) connected with field winding . which cause field current value become less and flux is also less so speed of motor increase.
By using this method motor speed only can be increase.

B. Armature control method 

Speed control of DC motor , speed control of dc series motor , speed control of dc shunt motor
Speed is inversely proportional to Armature current
In this method a variable resistance connect with Armature series which cause Armature voltage drop increase hence speed become less.
So by using this method motor speed being less.

C. Voltage control 

It is divided in two part
1. Multiple voltage control method
2. Ward Leonard method

1. Multiple voltage control method 

In this method field winding connect to directly  from line and given supply to Armature by help of varrier.
Supply voltage is directly proportional to motor Speed

2. Ward Leonard method 


In this method , motor and generator set are used to speed control of motor
Speed control of dc motor, speed control of dc series motor ,speed control of dc shunt motor



Hence from above method we can get variation in speed of DC  motor

so it is the basic type of speed control of dc motor. it is the main speed control method of dc motor if you fined any incorrect in this article please comment below.


For knowing more about speed control of dc motor please sea this video.

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