The alternator is the main power source of the car. Its function is to supply power to all electrical equipment (except the starter) when the engine is running normally, and to charge the battery at the same time. The performance of generators is in many ways superior to that of DC generators, which have been eliminated.
At present, the car uses a three-phase alternator with a diode rectifier circuit inside to rectify the alternating current into direct current. Therefore, the output of the automobile alternator is direct current. The alternator must be equipped with a voltage regulator, which controls the output voltage of the generator to keep it basically constant to meet the needs of automotive electrical appliances.
How Alternators Work？
Using the principle of electromagnetic induction to induce electric potential by cutting the magnetic lines of force, the mechanical energy of the prime mover is converted into electrical energy output. A synchronous generator consists of two parts, a stator and a rotor. The stator is the armature that generates the electricity and the rotor is the magnetic poles. The stator is composed of armature iron core, uniformly discharged three-phase winding, machine base and end cover. The rotor is usually hidden pole type, which is composed of excitation winding, iron core and shaft, guard ring, center ring and so on. The excitation winding of the rotor is fed with DC current to generate a magnetic field close to the sinusoidal distribution (called the rotor magnetic field), and its effective excitation flux intersects with the stationary armature winding. When the rotor rotates, the rotor magnetic field rotates together with it. Every time a revolution is made, the magnetic lines of force cut each phase winding of the stator in sequence, and a three-phase AC potential is induced in the three-phase stator winding. When the generator is running with a symmetrical load, the three-phase armature current is synthesized to generate a rotating magnetic field with synchronous speed. The stator and rotor fields interact to generate braking torque. From the steam turbine/water turbine/gas turbine, the input mechanical torque overcomes the braking torque to produce work.