Information about PMDC motor

2. CONTENTS
 Introduction
 Working principal of DC motor
 Construction of PMDC motor
 Rotor or armature of PMDC motor
 Working

3.  A current carrying conductor is placed inside
a magnetic field, there will be mechanical
force experienced by that conductor
 When permanent magnet is used to create magnetic
field in a DC motor, the motor is referred as
permanent magnet DC motor or PMDC motor
INTRODUCTION
 A DC motor in simple words is a device that
converts direct current(electrical energy) into
mechanical energy.

4. PMDC are best solutions to motion control and
power transmission applications where compact
size, wide operating speed range, ability to adapt
to a range of power sources or the safety
considerations of low voltage are important
Motivation to choose
this topic
ElectricChairs

5.  Magnets are mounted in periphery of this cylinder.
 The stator also serves as low reluctance return path
for magnetic field.
 Sometimes field coil is used in PMDC motor because if
permanent magnet lose their strength, these lost
strengths can be compensated by field excitation
through these field coils
STATOR

6.  made of number of varnish insulated, slotted
circular lamination of steel sheets
 Varnish insulated are used to reduce eddy current
loss
ROTOR(ARMATURE)
 Similar to DC motor
 Consists of core, windings, and commutator

7.  A stator and an armature
 N – pole and S – pole of each magnet are
alternatively faced towards armature
 Cylindrical stator serves as low reluctance return
path for the magnetic flux
 Permanent magnets lose their strength, these
lost magnetic strengths can be compensated by
field excitation through these field coils
CONSTRUCTION

8. Working principal of PMDC motor
A DC motor in simple words is a
device that converts direct
current(electrical energy) into
mechanical energy.

9. FLEMING’S LEFT HAND RULE
Fleming’s left hand rule says that if we extend the index finger,
middle finger and thumb of our left hand in such a way that the
current carrying conductor is placed in a magnetic field (represented
by the index finger) is perpendicular to the direction of current
(represented by the middle finger), then the conductor experiences
a force in the direction (represented by the thumb) mutually
perpendicular to both the direction of field and the current in the
conductor.

10.  The working principal of PMDC motor is same as the
working principal of DC motor
 Direction of this force is governed by Fleming’s left
hand rule
each conductor of the armature experiences the
mechanical force F=BIL
 When a carrying conductor comes inside a magnetic
field, a mechanical force will be experienced by the
conductor
 Each conductor of the armature experiences a force
and the compilation of those forces produces a
torque, which tends to rotate the armature.
WORKING

12.  For smaller ratings, use of permanent magnets reduces
manufacturing cost.
 No need of field excitation winding, hence construction is
simpler.
 No need of electrical supply for field excitation, hence
PMDC motor is relatively more efficient.
 Relatively smaller in size
 Cheap in cost
 The permanent magnets supply the surrounding field
flux, eliminating the need for external field current. This
design yields a smaller, lighter, and energy efficient
motor.
Advantages

13.  Since the stator in PMDC motor consists of permanent
magnets, it is not possible to add extra ampere-turns to
reduce armature reaction. Thus armature reaction is more in
PMDC motors.
 Stator side field control, for controlling speed of the motor, is
not possible in permanent magnet dc motors.
Disadvantages

14. APPLICATIONS
TOYS Drilling Machine ElectricToothbrush
Automatic Door opener Gear motor Coveyors

15. REFERENCE
 http://www.electrical4u.com
 http://www.completepowerelectronics.com/
 www.learnengineering.org

16. THANK YOU