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Operation of DC motor
A DC motor in simple words is a device that converts direct current (electrical energy) into
mechanical energy
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A currentcarrying conductor generates a magnetic field and when this is then placed in an external magnetic
field, it will experience a force proportional to the current in the conductor, and to the strength of
the external magnetic field
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The internal configuration of a DC motor is designed to harness the magnetic
interaction between a current-carrying conductor and an external magnetic field to generate
rotational motion
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Every DC motor has six basic parts -- axle, rotor (a
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a
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In most common DC motors (and all that BEAMers will see), the external
magnetic field is produced by high-strength permanent magnets1
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The rotor (together with the axle and attached commutator) rotate with respect to the stator
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The geometry of the brushes, commutator contacts, and rotor windings are such that when power
is applied, the polarities of the energized winding and the stator magnet(s) are misaligned, and the
rotor will rotate until it is almost aligned with the stator's field magnets
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Given
our example two-pole motor, the rotation reverses the direction of current through the rotor
winding, leading to a "flip" of the rotor's magnetic field, driving it to continue rotating
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In particular, this avoids "dead spots" in the commutator
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Meanwhile, with a two-pole motor, there is a moment
where the commutator shorts out the power supply (i
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, both brushes touch both commutator
contacts simultaneously)
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Yet another disadvantage of such a simple motor is that it would exhibit a high
amount of torque "ripple" (the amount of torque it could produce is cyclic with the position of the
rotor)
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Applications of motor
Series Motors
The series DC motors are used where high starting torque is required, and variations in speed are
possible
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Shunt Motors
The shunt motors are used where constant speed is required and starting conditions are not severe
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Compound Motors
The compound motors are used where higher starting torque and fairly constant speed is required
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Rotation (How it is maintained)
This DC or direct current motor works on the principal, when a current carrying conductor is placed
in a magnetic field, it experiences a torque and has a tendency to move
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If the direction of current in the wire is reversed, the direction of rotation also reverses
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Reversing switch

How can one reverse the rotation of a DC motor, depends on what type of DC motor
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

For a 3-phase brushless DC motor - you'd need to change commutation order, this is slightly
more complex because how to do that depends on what kind of position sensor is being
used
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For 3-phase brushless DC motors, if it tries to commutate
in the wrong order, you can risk damaging the motor or the motor driver
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Alternatively, you can
reprogram the motor driver controller
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