What is the composition principle of automobile generator?

1, the working principle of the generator is that when the AC electromotive force induced in the armature coil is led out from the brush end, it becomes DC electromotive force.

2. When there is no DC voltage on the brush, use the prime mover to drag the armature to rotate counterclockwise at a uniform speed, so that the magnetic lines of force under different polarity poles are cut on both sides of the coil, and the electromotive force is induced in it, and the direction of the electromotive force is determined according to the right-hand rule. This electromagnetic situation is shown in the figure.

3. Because the armature rotates continuously, it is necessary to make the coil sides ab and cd of the current-carrying conductor alternately cut the magnetic lines under the N pole and the S pole in the magnetic field, although the directions of the induced electromotive force in each coil side and the whole coil are alternating. The induced electromotive force in the coil is AC electromotive force, but the electromotive force at both ends of brushes A and B is DC electromotive force (more accurately, it is pulse electromotive force in the same direction). Because, in the process of armature rotation, no matter where the armature turns, the electromotive force drawn by the brush A through the commutator is always the electromotive force of the coil side cutting the N-pole magnetic field lines, so the brush A is always positive.

4. In the same way, the brush B is always negative, so the brush end can draw out the pulse electromotive force with the same direction but variable size. If the number of coils under each pole is increased, the degree of pulse vibration can be reduced and DC electromotive force can be obtained. This is the working principle of DC generator. At the same time, it also shows that DC generator is essentially an alternator with commutator.