DC motors are used for applications requiring variable speed control and are inexpensive and easy to operate. A DC motor consists of a stator with magnets that produces a stationary magnetic field, a rotor or armature made of windings that rotates when power is applied, a commutator that changes the current direction in the windings, and brushes that conduct current from the commutator to an external circuit. When current passes through the rotor windings in the magnetic field, it produces a torque due to the Lorentz force, causing the rotor to rotate. DC motors are classified as permanent magnet, series wound, shunt wound, compound wound, and brushless types depending on how the field windings are connected.

1. DC Motors
MECHATRONICS MODULE – 02 - ACTUATORS

2. Introduction to DC motors
DC MOTORS
 DC motors are used for
 Wide range of torques
 Constant & controlled speed
 Variable input supply.
 DC motors are widely used in applications ranging from
toys to push-button adjustable car seats.
 DC motors are inexpensive, easy to drive, and are readily
available in all sizes and shapes.
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3. Construction of DC motor
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4. Construction
MAGNETIC FRAME OR COVER
 Protective Cover for a system.
 Protects motor from any outside disturbance.
 Supports Armature through bearings.
 Houses field system.
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MAGNETIC
FRAME

5. Construction
STATOR MAGNETS
 Generates a stationary magnetic field that
surrounds the rotor.
 Magnetic field in generated by
 Permanent magnet
 electromagnets
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STATOR
MAGNETS

6. Construction
ROTOR
 Also called as ARMATURE
 made up of one or more windings.
 Free to rotate on supported bearings.
 the windings are constantly being
energized in a different sequence
 Number of windings – made of copper
wires
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ROTOR
WINDINGS

7. Construction
COMMUTATOR
 Cylindrical shape
 Made of copper
 Functions of commutator
 Collecting current from armature conductor.
 Constant contact with the brushes
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COMMUTATOR

8. Construction
BRUSHES
 Made of Carbon or GRAPHAITE
 Main function is to collect current for
battery and transfer to commutator
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BRUSHES

9. Construction
SHAFT
 Rotating part from with mechanical energy
is obtained.
 Armature is mounted over a shaft.
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SHAFT

10. ASSEMBLY OF DC MOTOR
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11. WORKING OF DC MOTORS
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12. Principle of operation
 Flemings left hand rule
“Magnetic field, Current and Force experienced are mutually perpendicular
to each other.”
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14. Working of DC Motor
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15. Working of DC Motor
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16. Advantages of DC motors
 Efficient and reliable.
 Quick response since high ratio of torque to rotor inertia.
 Controlled speed and reversible.
 More sturdy and Compact.
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17. Disadvantages of DC motors
 Brush wear: Since they need brushes to connect the rotor winding. Brush
wear occurs, and it increases dramatically in low‐pressure environment. So
they cannot be used in artificial hearts. If used on aircraft, the brushes
would need replacement after one hour of operation.
 Sparks from the brushes may cause explosion if the environment contains
explosive materials.
 RF noise from the brushes may interfere with nearby t.v. sets, or electronic
devices.
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18. Classification of DC motors
DCMOTORS
Brushed DC Motors
Permanent magnet
Series wound
Shunt wound
Compound
(Series + Shunt)Brushless DC motors
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19. Permanent Magnet
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The permanent magnet DC motor
consists of an armature winding as in
case of an usual motor, but does not
necessarily contain the field windings.
The construction of these types of DC
motor are such that, radially
magnetized permanent magnets are
mounted on the inner periphery of the
stator core to produce the field flux.
The rotor on the other hand has a
conventional dc armature with
commutator segments and brushes.
S1-S2 series field applied to the armature A1-
A2.

20. Series DC MOTORS
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S1-S2 series field applied to the armature A1-
A2.
In case of a series wound self excited
dc motor or simply series wound dc
motor, the entire armature current
flows through the field winding as its
connected in series to the armature
winding.

21. Shunt DC MOTORS
SHUNT FIELD IS PARALLEL TO ARMATURE
FIELD
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In case of a shunt wound dc motor or
more specifically shunt wound self
excited dc motor, the field windings are
exposed to the entire terminal voltage
as they are connected in parallel to the
armature winding

22. Compound DC MOTORS
The compound excitation characteristic
in a dc motor can be obtained by
combining the operational
characteristic of both the shunt and
series excited dc motor. The compound
wound self excited dc motor or simply
compound wound dc motor
essentially contains the field winding
connected both in series and in parallel
to the armature winding.
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23. Brushless DC motors (BLDC)
In order to make the operation more
reliable, more efficient, and less noisy
the recent trend has been to use
brushless D.C (BLDC) motors. They
are also lighter compared to brushed
motors with the same power output.
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24. Comparison of Dc motors
TYPE OF DC
MOTOR
COIL
RESISTANCE
SPEED
CONTROL
STARTING
TORQUE
SERIES LOW POOR HIGH
SHUNT HIGH GOOD AVERAGE
CONPOUND
PARALLE HIGH
+
SERIES LOW
AVERAGE AVERAGE
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25. THANK YOU….!!!