Working Principle of DC Generator
DC generator is an electrical machine which converts mechanical energy into electrical energy. The energy conversion is based on the principle of the production of dynamically induced emf according to Faraday’s law of Electromagnetic Induction. When a conductor is rotated in the magnetic field an emf is induced in it which is sinusoidal in nature. This emf causes a current flow to the conductor if the circuit is closed. The direction of induced emf can be found by Fleming right-hand rule.
Working of DC Generator
Magnetic Neutral Axis = Geometrical Neutral Axis
l = Active length of conductor
V = Velocity of the conductor
B = Magnetic field density
We assume from the above diagram that the coil rotates in clockwise direction. The rotating coil may be called armature and the magnets as field magnets. At position 1 & 5 maximum flux linked but the rate of change of flux is minimum thereby no emf induced in it. So that the axis which is perpendicular to magnetic field line is known as magnetical neutral axis (MNA) and the axis which bisects the center line of two adjacent poles known as geometrically neutral axis (GNA). As the coil rotates from position 1 & 3 the rate of change of flux linkages increase. At position 3, the flux link with the coil is minimum but the rate of change of flux is maximum and the induced emf also maximum. At position 3 & 5 induced emf gradually decreases with the decrease of the rate of change of flux linkages.
The direction of current reverse in every half cycle. For making the use of external circuit. We get the flow of current which is uni-direction in nature. commutator and split ring is used to convert alternating current (A.C) into direct current (D.C). Generally, we do not use split ring.