BLDC (BRUSLESS DC MOTOR)
BLDC (BRUSLESS DC MOTOR)
BRUSHLESS PERMANENT MAGNET DC MOTOR
BRUSHLESS DC ELECTRIC MOTOR ALSO KNOWN AS ELECTRONICALLY COMMUTATED MOTORS (ECMs, EC MOTORS) ARE SYNCHRONOUS MOTORS THAT ARE POWERED BY A DC ELECTRIC SOURCE VIA AN INTEGRATED INVERTER/SWITCHING POWER SUPPLY, WHICH PRODUCES AN AC ELECTRIC SIGNAL TO DRIVE THE MOTOR.
-MAGNETIC FIELDS GENERATED BY THE STATOR AND ROTOR ROTATE AT THE SAME FREQUENCY
-NO SLIP
-THE STATOR CONSISTS OF SEVERAL COILS WHICH CURRENT IS LED THROUGH CREATING A MAGNETIC FIELD THAT MAKES THE ROTAR TURNS.
CONSTRUCTION OF BLDC
1. IT CONSIST OF TWO PARTS MAINLY STATOR AND ROTOR STATOR
2. STATOR IS MADE UP OF SILICON STEEL STAMPINGS WITH SLOTS
3. THE SLOTS ARE ACCOMMODATED ARMATURE WINDINGS.
4. THIS WINDING IS WOUND WITH SPECIFIED NUMBER OF POLES (EVEN NUMBER)
5. THIS WINDING CONNECTED TO A DC SUPPLY THROUGH A POWER ELECTRONIC SWITCHING CIRCUITS (INVERTER CIRCUITS)
ROTOR
1.ROTOR IS OF PERMANENT MAGNET
2. NUMBER OF POLES ON ROTOR IS SAME AS THAT OF STATOR
3. ROTOR SHAFT CARRIES A RPS (ROTOR POSITION SENSOR) AND IT PROVIDES INFORMATION ABOUT THE POSITION OF SHAFT AT ANY INSTANT TO THE CONTROLLER WHICH SENDS SIGNAL TO THE ELECTRONIC COMMUTATOR.
4. THE ELECTRONIC COMMUTATOR FUNCTION IS SAME AS THAT OF MECHANICAL COMMUTATOR IN DC MOTOR.
BLDC MOTOR ROTORS
WORKING OF BLDC MOTOR
THE STATOR HAS A COIL ARRANGEMENT, AS ILLUSTRATED. THE INTERNAL WINDING OF THE ROTOR IS ILLUSTRATED. THE CORE HAS 3 COILS NAMED A, B, AND C.
OUT OF THESE 3 COILS, ONLY ONE COIL IS ILLUSTRATED. BY APPLYING DC POWER TO THE COIL, THE COIL WILL ENERGIZE AND BECOME AND ELECTROMAGNET.
THE OPERATION OF A BLDC IS BASED ON THE SIMPLE FORCE INTERACTION BETWEEN THE PERMANENT MAGNET AND THE ELECTROMAGNET. IN THIS CONDITION, WHEN COIL A IS ENERGIZED, THE OPPOSITE POLES OF THE ROTOR STATOR ARE ATTRACTED TO EACH OTHER. AS A RESULT, THE ROTOR POLES MOVE NEAR TO ENERGIZED STATOR.
AS THE ROTOR NEARS COIL A, COIL B IS ENERGIZED. AS THE ROTOR NEARS COIL B, COIL C IS ENERGIZED. AFTER THAT COIL A IS ENERGIZED WITH THE OPPOSITE POLARITY. THIS PROCESS IS REPEATED, AND THE ROTOR CONTINUES TO ROTATE. THE DC CURRENT REQUIRED IN EACH COIL.
ADVANTAGES
1. INCREASED RELIABILITY AND EFFICIENCY
2. LONGER LIFE
3. ELIMINATION OF SPARKS FROM COMMUTATOR
4. REDUCED FRICTION
DISADVANTAGES
1. REQUIRE COMPLEX DRIVE CIRCUITRY
2. REQUIRES ADDITIONAL SENSORS
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