Brushless DC motor CIIT Abbottabad

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BRUSHLESS DC MOTOR

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Brushless DC motor CIIT Abbottabad

  1. 1. BRUSH-LESS DC MOTOR • Group Members • SYED AHMED SHAH SP12-BCE-052 • M.UMAR IFTIKHAR SP12-BCE-034 • FAREEHA AZAM SP12-BCE-033 • AHSAN RAZA SP12-BCE-009
  2. 2. INTRODUCTION: • What is Brushless DC motor? • Why we use brushless DC motor? • Structure • Components of BLDC • Working of BLDC • Uses • Advantages • Disadvantages
  3. 3. WHAT IS BLDC MOTOR? • As its name indicates, it runs on DC power source but don’t have commutator and Brushes. • Brushes and commutator are removed in BLDC motor.
  4. 4. WHY WE USE BLDC? • When our power source is DC like that of automobiles and aircraft we use DC motor. • For e.g. in aircraft, on high altitude, we experience low air pressure, which cause brush wear that is very bad which results in maintenance of brushes even after less than one hour. • superior efficiency, long life, smooth torque delivery, and high speed operation
  5. 5. DIFFERENCE B/W BLDC AND DC • Excessive sparking and brush wear. • Small in size so compensating poles cannot be placed to minimize armature reaction which causes sparking which is dangerous. • High speed DC motors causes increased brush wear. • No brushes in BLDC so no Sparking and no brush wear and no replacement of brushes.
  6. 6. COMPONENTS OF BLDC • A permanent magnet rotor. • A stator with a three-four or more phase windings. • A rotor position sensor. • An electronic circuit to control the phases of the rotor winding.
  7. 7. STRUCTURE OF BRUSHLESS MOTOR
  8. 8. DIAGRAM:
  9. 9. WORKING OF BLDC • A BLDC motor functions by energizing one stator coil at a time with a constant dc voltage. • When a coil is turned on it produces a stator magnetic field Bs and a torque is produced on the rotor given by • T(ind)=kBr x Bs • Which tends to align the rotor with the stator magnetic field. The stator magnetic field Br points up producing a counter clockwise torque on the rotor. As a result the rotor will turn to the left.
  10. 10. WORKING PRINCIPLE:
  11. 11. WORKING PRINCIPLE
  12. 12. WORKING PRINCIPLE:
  13. 13. WORKING OF BLDC • If the coil a remained energized all the time , the rotor would turn until the two magnetic field were aligned, then it would stop , just like a stepper motor. • The key to the operation of a brushless dc motor is that it includes a position sensor , so that the control will know when rotor is almost aligned with the stator magnetic field.
  14. 14. WORKING OF BLDC • The position sensor is used to switch the energized stator coil whenever the rotor is almost aligned with it , keeping the rotor rotating a speed set by the control electronics.  Electronic control controls speed and direction of the motor.
  15. 15. WORKING OF BLDC • Salient pole rotors are used in application with speeds from 100 to 1500rpm. They are alternative known as "projected pole" type of rotors. • Non-salient pole rotors are generally used in application which operate at higher speeds, 1500rpm and above. The prime movers in these • applications are generally gas or steam turbines.
  16. 16. USES • Because a computer controls the motor instead of mechanical brushes, it's more precise. The computer can also factor the speed of the motor. This makes brushless motors more efficient. • There is no sparking and much less electrical noise. • There are no brushes to wear out. • With the electromagnets on the stator, they are very easy to cool. • You can have a lot of electromagnets on the stator for more precise control.
  17. 17. ADVANTAGES • Relatively high efficiency. • Long life and high reliability. • Little or no maintenance . • Less RF noise as compare with the dc motor. • Very high speeds are possible (greater than 50,000 rpm)
  18. 18. DISADVANTAGES • The only disadvantage of a brushless motor is its higher initial cost as compare with the brush dc motor but you can often recover that cost through the greater efficiency over the life of the motor • Blushless DC motor are available only in small size ,up to 20W.
  19. 19. RELATION B/W SPEED AND TORQUE

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