speed control of dc motor

1. • Presenter…
-Sumeet Patel (99)
DC MOTORS

2. TOPICS TO DISCUSS
 Introduction to DC MOTORS.
 Principle.
 Construction.
 Working.
 Types.
 Applications.

3. • A DC motor or Direct
Current Motor converts
electrical energy into
mechanical energy.
• A direct current (DC) motor is a fairly simple electric
motor that uses electricity and a magnetic field to
produce torque, which turns the rotor and hence give
mechanical work.
DC MOTOR

4. PRINCIPLE OF DC MOTORS
• In any electric motor, operation is
based on simple
electromagnetism.
• When a current-carrying
conductor is placed in an external
magnetic field, it will experience a
force i.e. Lorentz force.
• Due to this force torque is
produced which rotates the rotor
of motor and hence a motor runs.

5. • DC motor consist of 2 windings…
1. Field winding.
2. Armature winding.
• Field winding is stationary and
armature winding can rotate
freely.
• Field windings when given DC
supply, magnetic field is produced.
• Armature winding when
connected to DC source, shaft
connected to it rotates due to
Lorentz force.
CONSTRUCTION

7. WORKING OF DC MOTORS

8. TYPES OF DC MOTORS
• DC motor are of 3 types they are…..
1. DC SHUNT MOTOR
2. DC SERIES MOTOR
3. DC COMPOUND MOTOR

9. 1. DC SHUNT MOTOR
Armature
• The parallel combination of two
windings is connected across a
common dc power supply.
• The resistance of shunt field
winding (Rsh) is always higher
than that is armature winding.
• This is because the number of
turns for the field winding is more
than that of armature winding.
• The cross-sectional area of the
wire used for field winding is
smaller than that of the wire used
for armature winding.

10. 2. DC SERIES MOTOR
• The field winding is connected in
series with the armature.
• The current passing through the
series winding is same as the
armature current .
• Therefore the series field winding
has fewer turns of thick wire than
the shunt field winding.
• Also therefore the field winding
will posses a low resistance then
the armature winding.

11. 3. DC COMPOUND MOTOR
DC
COMPOUND
MOTOR
LONG SHUNT
COMPOUND
MOTOR
SHORT SHUNT
COMPOUND
MOTOR
CUMULATIVE
COMPOUND
MOTOR
DIFFERENTIAL
COMPOUND
MOTOR

12. I. LONG SHUNT COMPOUND MOTOR
• In this the series winding is
connected in series with the
armature winding and the
shunt winding is connected in
parallel with the armature
connection.

13. II. SHORT SHUNT COMPUND MOTOR
• In short shunt compound
motor the series winding is
connected in series to the
parallel combination of
armature and the shunt
winding
• This is done to get good
starting torque and constant
speed characteristics.

14. a) CUMULATIVE COMPOUND DC MOTORS
b) DIFFERENTIAL COMPOUND DC MOTORS
• If the two field windings i.e. series and
shunt are wounded in such a way that the
fluxes produced by them add or assist
each other
• If the two field winding i.e. series and
shunt are wounded in such a way that the
fluxes produced by them always try to
oppose and try to cancel each other.

15. APPLICATIONS OF DC MOTORS
MOTORS.. APPLICATIONS…
D.C. SHUNT MOTOR
LATHES , FANS, PUMPS DISC AND
BAND SAW DRIVE REQUIRING
MODERATE TORQUES.
D.C. SERIES MOTOR ELECTRIC TRACTION, HIGH SPEED
TOOLS
D.C. COMPOUND MOTOR
ROLLING MILLS AND OTHER LOADS
REQUIRING LARGE MOMENTARY
TORQUES.

16. BIBLIOGRAPHY
www.google.com
en.wikipedia.org
Electrical technology
–B.L. Theraja
–A.K. Theraja

18. ANY QUESTIONS ???