Working principle of automobile generator

The automobile generator is an important part of the car's power system. The automobile generator not only provides electric energy for the automobiles but also charges the car battery. Most of the current car generators are alternators.

Ⅰ.Introduction to the working principle of automobile generator

The working principle of a car alternator is similar to that of a traditional electric motor. The automobile generator is composed of a rotor and a stator. The rotor has permanent magnets or electromagnets inside, and the stator has stator windings inside. When a car engine starts, the crankshaft begins to rotate, which in turn drives the rotor of the car's generator. At this time, the magnetic poles of the permanent magnets or electromagnets inside the rotor interact with the magnetic field of the stator winding to form a magnetic field. Due to the changing effect of the magnetic field, an induced current with varying magnitude and direction will be generated in the coil, and the current will be delivered by the stator coil.

Ⅱ. Structural Principles of Automotive Generators

An alternator generally consists of a rotor, a stator, a rectifier, front and rear bearing caps, etc. Here we mainly introduce the automobile generator rotor, automobile generator stator, and rectifier.

1. Car generator rotor

The function of the car generator rotor is to generate a rotating magnetic field.

The rotor is the magnetic field component of the generator. The rotor consists of claw poles, a magnetic yoke, magnetic field winding, a collector ring, and a rotor shaft.

Two claw poles are mounted on the rotor shaft. Each of the two claw poles has six beak-shaped magnetic poles. The cavity of the claw pole is equipped with a magnetic field winding and a magnetic yoke. The collector ring consists of two copper rings that are insulated from each other. The collector ring is press-fitted on the rotor shaft and insulated from the shaft. The two collector rings are connected to both ends of the magnetic field winding respectively.

When DC is supplied to the two collector rings (through the brush), current passes through the magnetic field winding, and axial magnetic flux is generated, causing one claw pole to be magnetized to the N pole and the other to the S pole, thus forming Six pairs of interlaced magnetic poles. When the rotor rotates, a rotating magnetic field is formed.

2. Car generator stator

The function of the car generator stator is to generate alternating current.

The car generator stator consists of a stator core and a three-phase stator winding, which is fixed between the front and rear end covers.

The stator core of the generator is made of ring-shaped silicon steel sheets, which are insulated from each other. There are slots in the inner circle of the stator, and three-phase stator windings are embedded in the slots. For a rotor with 6 pairs of magnetic poles, each set of windings has 6 coils connected in series, forming a three-phase winding. Due to changes in the magnetic field, the potential difference inside the stator winding also begins to change. This potential difference causes current to flow inside the stator windings, producing electrical energy.

3. Automotive generator rectifier

The output current of the car generator needs to be converted by a rectifier before it can be used to charge the battery and drive the car's electrical equipment. The rectifier converts the alternating current output from the generator into direct current, which is then transferred to the battery. In this way, the battery can be charged.

In the actual car generator motor, some control circuits are also involved to better control the power output and battery charging. These control circuits can adjust the current of the excitation winding by monitoring the output voltage and current of the generator, thereby controlling the power output of the generator. In addition, the battery's charge status can be monitored through the battery management system to avoid overcharging or discharging.

Ⅲ. Principle of automobile generator testing

The car generator is an integral part of the car's power system, so the quality of the car generator is very important.

Generally, car companies have relatively high-quality requirements for car engines. In response to this demand, based on the above working principles of car generators, the car generator motor testing system developed by AIP tests the complete generator and stator and specifically tests the car. Generator DC resistance, surge, AC hi-pot, no-load/load output voltage, and other items are tested.