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Brushless DC Motors. Sohaib Hasan. Motor Basics. What is a motor Converts electrical energy into kinetic energy Where did it come from Identification of rotating magnetic field principle by Nicola Tesla in 1882
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Brushless DC Motors Sohaib Hasan
Motor Basics • What is a motor • Converts electrical energy into kinetic energy • Where did it come from • Identification of rotating magnetic field principle by Nicola Tesla in 1882 • Introduction of Electric Motor by Nicola Tesla in December 1889 (U.S. Patent 0416194)
End Bell Fastners Shaft Key & Keyways Bearing & Brushings End Ball Flanges Identification Plates Wire Warnish Commutators Brush Holders Laminations Conduit Connection Box Magnets (Ferrites) Parts of a Motor Brushless Motor Components Brush Type Motor Components Images courtesy of Hernon Adhesives & Sealents (http://www.hernonmfg.com/electricmotor.htm)
Parts of a Motor Images courtesy of How Stuff Works (http://electronics.howstuffworks.com/motor3.htm)
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 How It Works Images courtesy of Wikipedia (http://en.wikipedia.org/wiki/Electric_motor)
Brushless DC Motor • No Commutators • Position of Coils with respect to the magnetic field is sensed electronically. • Current is commutated through electronic switches to appropriate phases.
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 Images courtesy of Servo Magnetics (http://www.servomag.com/flash/2-pole/2pole-bldc-motor.html)
Advantages • Increased Reliablilty & Efficiency • Longer Life • Elimination of Sparks from Commutator • Reduced Friction • Faster Rate of Voltage & Current • Precision Voltage & Current Applied to Field Coils
Applications • Low Power • Consumer Electronics • Medical Field • High Power • Industrial Machinery • Vehicles • Airplanes
Disadvantages • Requires Complex Drive Circuitry • Requires additional Sensors • Higher Cost • Some designs require manual labor (Hand wound Stator Coils)
Useful Links • http://en.wikipedia.org/wiki/Electric_motor • http://electronics.howstuffworks.com/motor3.htm • http://www.hernonmfg.com/electricmotor.htm • http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html • http://www.servomag.com/flash/2-pole/2pole-bldc-motor.html • http://www.engineersedge.com/motors/brushless_dc_motor.htm • http://www.freescale.com/webapp/sps/site/application.jsp?nodeId=02nQXGrrlPY7r803B5