How does a car generator work?

The power supply of the car is composed of the car generator and the battery in parallel. The battery provides electric energy for the vehicle electric appliances in the state of engine flameout, and at the same time provides electric energy for the starter when the vehicle starts, so that the engine starts. When the engine starts successfully, it drives a generator to generate electricity. The generator charges the battery and supplies power to the vehicle.

A Diagram Of The Working Principle Of An Automobile Generator

The car generator is a three-phase ac generator, and the electricity it generates is three-phase ac. The generator consists of several key components, such as the stator and rotor, which are wound by coils, and the rectifier bridge, which is made of silicon diodes.

Apply an electric current to the rotor and it forms a magnetic field. If the rotor of the generator rotates with the engine, the magnetic field is a rotating magnetic field.

The corresponding coil installed outside the rotor is a stator coil, the stator coil is composed of three groups of coils, they stagger 120 degrees each other, the three groups of coils in accordance with the triangle connection method leads to three taps. As the rotor rotates, the three taps of the stator coil can sense an ALTERNATING current with a phase difference of 120 degrees. This alternating current passes through the bridge rectifier circuit and becomes 14V direct current to power the vehicle.

The rotor of the generator rotates with the engine. The higher the engine speed, the higher the output voltage of the generator, and the lower the engine speed, the lower the output voltage of the generator. But we need a constant 14V output from the generator at all times. This requires a device that can adjust the output voltage.

Principle Of Auto Generator Adjusting Voltage

To adjust the voltage of the car generator, it is only necessary to adjust the excitation current of the rotor. The device that adjusts the output voltage according to the excitation current is called the voltage regulator, and the voltage regulator can be divided into built-in regulator and external regulator according to the installation position.

Now you can't see the external regulator on the car, so I won't introduce it. A built-in voltage regulator is shown mounted at the rear of the generator. There are two brushes on the voltage regulator, which press directly on the rotor to provide excitation current to the rotor. The power supply of the voltage regulator varies according to the circuit structure of different models. Specifically, see the control logic of the generator circuit of each model.