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BRUSHLESS D.C MOTORS Prepared by… FAKHRI KHALIFEH

BRUSHLESS D.C MOTORS Prepared by… FAKHRI KHALIFEH. Contents…. Abstract. Introduction. Basics of a motor. Classification. Brushed motors. BLDCM. Working procedure. Applications. Advantages. Disadvantages. Conclusion. Reference. Abstract….

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BRUSHLESS D.C MOTORS Prepared by… FAKHRI KHALIFEH

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  1. BRUSHLESS D.C MOTORS Prepared by… FAKHRI KHALIFEH

  2. Contents… • Abstract. • Introduction. • Basics of a motor. • Classification. • Brushed motors. • BLDCM. • Working procedure. • Applications. • Advantages. • Disadvantages. • Conclusion. • Reference.

  3. Abstract… • Permanent magnet (PM) brushless DC motors (BLDCM) are generated by virtually inverting the stator and rotor of PM DC motors. • These motors are actually fed by rectangular AC waveform. • The advantage is the removal of brushes, leading to eliminate many problems associated with brushes. • Another advantage is the ability to produce a larger torque because of the rectangular interaction between current and flux.

  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. MOTOR… • MOTOR… >> Converts electrical energy to mechanical energy. • ORIGIN... >> Nicola Tesla introduces electric motor in December 1889. >> He identifies the principle of rotating magnetic field.

  6. Main parts of brushed motor... • Commutator : >> Facilitate collection of current from the armature conductors. • Brush : >> Collects current from the commutator.

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

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

  9. Classification…

  10. BLDCM… • Has no brushes and commutators. • Rotation of the rotor depends on the accurate position with stator. • Detected by Hall Sensor, mounted on rotor, shifted at 60º or 120º phase shift. • Electronic commutation used to vary the PWM duty-cycle for speed control, using software.

  11. Working of BLDCM… • As there is no commutator ,the current direction of the conductor on the stator controlled electronically. • Rotor consists the permanent magnet where as stator consist a no. of windings. Current through these winding produces magnetic field and force. • Hall sensor used to determine the position during commutation.

  12. Commutation of BLDCM… • Brushless DC motor requires external commutation circuit to rotate the rotor. • Rotor position is very important. • HALL SENSOR senses the position of the coil accurately.

  13. Working Procedure… • When electric current passes through a coil in a magnetic field, the magnetic force produces a torque which turns the motor. • Force in Motor: • F=ILB • F = Force • B = Magnetic Field • L = Length of Conductor • I = Current in Conductor • Torque in Motor: • T = IBA sin θ • A = LW • L = Length of Winding • W = Width of Winding

  14. Working Procedure… • 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.

  15. Pros… • In BLDC motor PM are on the rotor & electromagnets are on the stator controlled by software. Thus the advantages are: • Because of computer control it is more precise & more efficient. • There is no sparking & less electrical noise. • Voltage and current rating is high. • High speed can be achieved. • As there is no brushes it requires no servicing. • It has longer life. • Low Radio Frequency Interference and electromagnetic Interference.

  16. Cons… • Requires Complex Drive Circuitry. • Requires additional Sensors. • Expensive. • Some designs require manual labor. (Hand wound Stator Coils)

  17. Applications… • PMBLDC motors are increasingly being used in a wide spectrum of applications: • domestic equipments, • automobiles • information technology equipment • industries • public life appliances • transportation • aerospace, defence equipments, power tools, toys, vision and sound equipments • medical and health care equipment ranging from microwatts to megawatts.

  18. Reference… http://en.wikipedia.org/wiki/Alternator http://en.wikipedia.org/wiki/Electric_motor http://www.basler.com Thompson, Sylvanus P., Dynamo-Electric Machinery, A Manual for Students of Electro techniques, Part 1, Collier and Sons, New York, 1902 White, Thomas H.,"Alternator-Transmitter Development (1891-1920)". EarlyRadioHistory.us. S.M.L.Kabir, R.Shuttle worth, “Brushless Exciter Model”.

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