The car generator is the main power source of the car. When the engine is running normally, all the electric energy on the car is provided by the generator. The remaining electric energy will also charge the battery. At present, most of the generators used in automobiles are silicon rectifier three-phase alternator, whose main structure is composed of rotor, stator, brush and slip ring mechanism, three-phase bridge rectifier, bearing, fan and front and rear end covers.
So how does a generator produce electricity? When the ignition switch is turned on, the battery energizes the rotor coils of the generator, creating a magnetic field in a process called "excitation." At the beginning of the generator operation, this excitation current is provided by the battery, called "other excitation"; When the generator is running properly and has produced enough electricity, this excitation current is provided by the generator itself, which is called "self-excitation". Then the rotor of the generator rotates at a high speed driven by the crankshaft of the engine, and the stator coil will cut the magnetic field lines of the rotor coil. According to Lenz's law, when the moving conductor cuts the magnetic field lines, the current will be generated in the stator coil. This is how the generator generates electricity. But the electricity from this is three-phase alternating current, is not directly used in the car, it must be rectified into direct current. The work is done by a rectifier mounted on the back cover of the generator. It is a bridge rectifier circuit consisting of six diodes that converts three-phase alternating current into a pulsating DC voltage.
