Brushless DC Motors - EEERulez.BlogSpot.in

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Brushless DC Motor(BLDC)

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

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Brushless DC Motors - EEERulez.BlogSpot.in

  1. 1. Brushless DC Motors EEERulez.BlogSpot.in
  2. 2. Motor Basics• What is a motor Converts electrical energy into kinetic energy• How it works
  3. 3. 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 magnetsare inside• The stator consists of severalcoils which current is led throughCreating a magnetic field thatmakes the rotor turns
  4. 4. Construction• Stator consists of stacked steellaminations with windings placed in the slots that are axially cut along theinner periphery• Rotor is made of permanent magnet and can vary from two toeight pole pairs with alternate North (N) and South (S) poles. Ferrite magnets and Rare earth alloy magnets are used in rotor
  5. 5. Unlike a brushed DC motor, the commutationof a BLDC motor is controlled electronically.It is important to know the rotor position in orderto understand which winding will be energizedfollowing the energizing sequence.Rotor position is sensed by different ways someof them are1) Hall sensors2) Optical encoders
  6. 6. Hall SensorsWhen a magnetic field applied to a system with electric current ahall voltage Perpendicular to the field and to current is generated.This was discovered by Edwin Hall in 1879.
  7. 7. 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
  8. 8. Torque generation Fig 2 Fig 1 Fig 3
  9. 9. TORQUE/SPEED CHARACTERISTICS
  10. 10. Advantages• Increased Reliability & Efficiency• Longer Life• Elimination of Sparks from Commutator• Reduced Friction• Faster Rate of Voltage & Current
  11. 11. Disadvantages• Requires Complex Drive Circuitry• Requires additional Sensors• Higher Cost• Some designs require manual labor(Hand wound Stator Coils)
  12. 12. ApplicationsConsumer: Hard Drives, CD/DVDDrives, PC Cooling Fans, toys, RCairplanes, air conditioners
  13. 13. Medical: Artificial heart,Microscopes, centrifuges,Arthroscopic surgical tools, Dentalsurgical tools and Organ transportpump system.
  14. 14. Vehicles: electronic power steering, personal electric vehiclesAirplanes: 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
  15. 15. Closing thoughts Given the existing availability and firstcost penalty, BLDC technology will find greatest acceptance wherever its performance advantage over a wide speed range can be combined with its excellent variable-speed capabilities. we can expect this combination to yield an efficiency improvement of at least 30 percent over single-speed AC induction motors EEERulez.BlogSpot.in

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