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As mentioned in the main article, Electric motorsmotor, in a DC motor the magnetic field is created by the current through the field winding (coils) in the stator. This field is always at right angles to the field created by the armature winding or the permanent magnet. This condition, known as field orientation, is needed to generate maximum torque. The commutator and brush assembly ensures that the condition is maintained regardless of the rotors position. Once field orientation is active, the DC motor’s torque is easily controlled by altering the armature current and by keeping the magnetising current constant. The advantage of the DC drive is that speed and torque are controlled directly through armature current. By this definition any device which controls the armature current or the magnetic field is a drive.
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