Brushless DC Motors Sohaib Hasan Motor Basics What
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)
Parts of a Motor Brushless Motor Components Brush Type Motor Components 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. End Bell Fastners Shaft Key & Keyways Bearing & Brushings End Ball Flanges Identification Plates Wire Warnish Commutators Brush Holders Laminations Conduit Connection Box Magnets (Ferrites) 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/motor 3. htm)
How It Works • 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 Images courtesy of Wikipedia (http: //en. wikipedia. org/wiki/Electric_motor)
Motor Types
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/2 pole-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 wound Stator Coils) (Hand
Useful Links • http: //en. wikipedia. org/wiki/Electric_motor • http: //electronics. howstuffworks. com/motor 3. htm • http: //www. hernonmfg. com/electricmotor. htm • http: //hyperphysics. phy-astr. gsu. edu/hbase/hframe. html • http: //www. servomag. com/flash/2 -pole/2 pole-bldc-motor. html • http: //www. engineersedge. com/motors/brushless_dc_motor. htm • http: //www. freescale. com/webapp/sps/site/application. jsp? node. Id=02 n. QX Grrl. PY 7 r 803 B 5
- Slides: 12