Working Principle of DC Motor

Working Principle of DC Motor Points : Working Principle of DC Motor The principle upon which a dc motor works is very simple. If a current carrying conductor is placed in a magnetic field, mechanical force is experienced on the conductor, the direction of which is given by Fleming’s left hand rule (also called motor rule) and hence the conductor moves in the direction of force. The magnitude of the mechanical force experienced on the conductor is given by
F = BI_C 1_c newtons

Where B is the field strength in teslas (Wb/m₂), I is the current flowing through the conductor in amperes and i is the length of conductor in meters.

When the motor is connected to the dc supply mains, a directed current passes through the brushes and commutator to the armature winding; while it passes through the commutator it is converted into ac so that the group of conductors under successive field poles carry currents in the opposite direction. Also the direction of current in the individual conductors reverses as they pass away from the influence of one pole to that of the next.

When the field and armature circuits are connected across dc supply mains. Let the current in armature conductors be outwards under the N-poles (shown by dots) and inwards under S-poles (shown by crosses). By applying Fleming’s left hand rule, the direction of force on each conductor can be determined, which has been illustrated into 3-2 from 3-2 it is observed each conductor experiences a force which tends to rotate the motor armature in clock-wise direction. These force collectively produce a driving torque.