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Saturday, August 3, 2019

Brushless DC Motor and How Does It Work

What is a Brushless DC Motor and How Does It Work?

Brushless DC motors are common in industrial applications across the world.A brushless DC motor consists of a rotor in form of a permanent magnet and stator in form of polyphase armature windings. It differs from conventional dc motor in such that it doesn’t contains brushes and the commutation is done using electrically, using a electronic drive to feed the stator windings


Brushless DC motors typically have an efficiency of 85-90%, while brushed motors are usually only 75-80% efficient. Brushes eventually wear out, sometimes causing dangerous sparking, limiting the lifespan of a brushed motor. Brushless DC motors are quiet, lighter and have much longer lifespans. Because computers control the electrical current, brushless DC motors can achieve much more precise motion control.

Principle of Working
The principles for the working of a BLDC motors are the same as for a brushed DC motor, i.e., the internal shaft position feedback. In case of a brushed DC motor, feedback is implemented using a mechanical commutator and brushes. Within BLDC motor, it is achieved using multiple feedback sensors. In BLDC motors we mostly use Hall-effect sensor, whenever rotor magnetic poles pass near the hall sensor, they generate a HIGH or LOW level signal, which can be used to determine the position of the shaft. If the direction of the magnetic field is reversed, the voltage developed will reverse too.

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