The working principle of a BLDC motor is _____.

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SSC JE Electrical 14 Nov 2022 Shift 3 Official Paper

Answer 1

Brushless DC motor (BLDC) motor

F1 Jai 13.3.21 Madhu D1

A brushless DC motor is an electronically commuted DC motor that does not have brushes like conventional DC motors.
The controller provides pulses of current to the motor windings which control the speed and torque of this motor.
The working principle of a BLDC motor is based on Lorentz force law.
The Lorentz force law states that whenever a current-carrying conductor is placed in a magnetic field it experiences a force. As a consequence of reaction force, the magnet will experience an equal and opposite force.
With the brushed motor, rotation is achieved by controlling the magnetic fields generated by the coils on the rotor, while the magnetic field generated by the stationary magnets remains fixed.
To change the rotation speed, you change the voltage for the coils.
With a BLDC motor, it is the permanent magnet that rotates ( N and S ); rotation is achieved by changing the direction of the magnetic fields generated by the surrounding stationary coils. To control the rotation, you adjust the magnitude and direction of the current into these coils.