This document is a seminar paper on brushless DC motors submitted for a bachelor's degree. It includes sections on motor basics, the principles of BLDC motors, their construction including hall sensors, how BLDC motors work, torque/speed characteristics, advantages like increased efficiency over brushed DC motors, disadvantages like more complex circuitry, and applications in devices like hard drives, medical tools, and vehicles.

1. A
Seminar
on
BRUSHLESS DC MOTOR
Submitted in partial fulfillment of the Requirements for the award of
BACHELOR OF TECHNOLOGY
In
ELECTRICAL AND ELECTRONICS ENGINEERING
By
V.VINAY (167 05A0248)
II B.Tech EEE
Under the esteemed guidance of
Mr. C. GANESH, M.Tech ,
Associate Professor
DEPARTMENT OF ELECTRICALAND ELECTRONICS ENGINEERING
ANNAMACHARYA INSTITUTE OF TECHNOLOGY AND SCIENCES, RAJAMPET
(An Autonomous Institution)
2016-17

2. Brushless DC Motors

3. Contents…
• Introduction
• Motor basics
• Principles of BLDC motor
• Construction
• Hall sensors
• How it works
• Torque/speed characteristics
• Advantages
• Disadvantages
• Applications
• Conclusion

4. Introduction…
• Classical DC motors are no doubt good and
simple but inefficient in some ways.
• Although dc motors possess good control
characteristics and ruggedness, their performance
and applications are inhibited due to sparking and
commutation problems.
• The Permanent Magnet Brushless DC
(PMBLDC) motor is able to overcome the
limitations mentioned above and satisfy the
requirements of a variable speed drive.

5. • What is a motor
Converts electrical energy into kinetic energy
• How it works
Motor Basics

6. Brushless DC Motor(BLDC)
Principles
• A BLDC is simply a normal dc motor turned inside out,
that means the coil is on the out side and the magnets
are inside
• The stator consists of several
coils which current is led through
Creating a magnetic field that
makes the rotor turns

7. Construction
• Stator consists of stacked steel
laminations with windings placed in
the slots that are axially cut along the
inner periphery
• Rotor is made of permanent magnet and can vary from two to
eight pole pairs with alternate North (N) and South (S) poles.
Ferrite magnets and Rare earth alloy magnets are used in rotor

8. Unlike a brushed DC motor, the commutation
of a BLDC motor is controlled electronically.
It is important to know the rotor position in order
to understand which winding will be energized
following the energizing sequence.
Rotor position is sensed by different ways some
of them are
1) Hall sensors
2) Optical encoders

9. Hall Sensors
When a magnetic field applied to a system with electric current a
hall voltage Perpendicular to the field and to current is generated.
This was discovered by Edwin Hall in 1879.

10. How it works
• Halls Sensors
sense the position of
the coils
• The Decoder Circuit
turns appropriate
switches on and off
• The voltage
through the specific
coils turns the motor

11. TORQUE/SPEED CHARACTERISTICS

12. Advantages
• Increased Reliability & Efficiency
• Longer Life
• Elimination of Sparks from Commutator
• Reduced Friction
• Faster Rate of Voltage & Current

13. Disadvantages
• Requires Complex Drive Circuitry
• Requires additional Sensors
• Higher Cost
• Some designs require manual labor
(Hand wound Stator Coils)

14. Applications
Consumer: Hard Drives, CD/DVD
Drives, PC Cooling Fans, toys, RC
airplanes, air conditioners

15. Medical: Artificial heart,
Microscopes, centrifuges,
Arthroscopic surgical tools, Dental
surgical tools and Organ transport
pump system.

16. Vehicles: electronic power steering,
personal electric vehicles
Airplanes: an electric self launching
sailplane, flies with a 42kW DC/DC
brushless motor and Li-Ion batteries and
can climb up to 3000m with fully charged
cells

17. Conclusion
• Although Brushless DC Motors are more expensive of
the same kW rating than conventional DC Motor but
there are many advantages.
• Brushless DC Motors can run when submerged in
fluids.
• Brushless DC Motor does not produce brush or
commutator particles or gases as by-products of
operation.