ALTERNATOR ASSEMBLY W23601.08100.01W

When the external circuit passes through the brushes to supply current to the excitation winding, a magnetic field is generated, causing the pawl poles to be magnetized as N poles and S poles. When the rotor rotates, the magnetic flux alternates in the stator windings. According to the principle of electromagnetic induction, an alternating induced electromotive force is generated in the three-phase stator windings. This is the principle of generating electricity in an alternator.

The synchronous generator rotor driven by the prime mover (i.e., the engine) rotates at a speed of n (rpm), and the three-phase stator windings induce an alternating electric potential. If the stator windings are connected to an electrical load, the motor can output alternating electrical energy, and the alternating current is converted into direct current by the rectifier bridge inside the generator and is output from the output terminals.

The alternator is composed of two parts: the stator winding and the rotor winding. The three-phase stator winding is evenly distributed on the housing at an electrical angle of 120 degrees from each other. The rotor winding consists of two pole claws. When the rotor winding is connected to a direct current, it is excited. The two pole claws form the N pole and the S pole. The magnetic lines of force start from the N pole, pass through the air gap, enter the stator core, and return to the adjacent S pole. Once the rotor rotates, the rotor winding will cut the magnetic lines of force, generating a sinusoidal electromotive force with an electrical angle difference of 120 degrees in the stator winding. This is the three-phase alternating current. It is then converted into direct current through a rectifier element composed of diodes.

Battery positive terminal → Charging indicator light → Regulator contact → Excitation winding → Ground → Battery negative terminal. At this time, the charging indicator light will be on because there is current passing through it.

However, after the engine starts, as the generator speed increases, the output voltage of the generator also continuously rises. When the output voltage of the generator is equal to the voltage of the battery, the potential at the "B" and "D" terminals of the generator is the same. At this point, the charging indicator light will go out because the potential difference between the two ends is zero. This indicates that the generator is working normally, and the excitation current is supplied by the generator itself. The three-phase alternating current generated by the three-phase windings in the generator is rectified by the diodes, and then output as direct current, which supplies power to the load and charges the battery.