Research on the Fault and Detection of Automobile Generators Abstract: The AC generator is an important power source for automobiles, and it works in conjunction with the generator regulator. Its main task is to supply power to all electrical equipment (excluding starters) and charge the battery during normal operation of the generator. As an important part of automobiles, the importance of automotive generators is constantly increasing with the increasing level of electrification. So the detection of the generator voltage regulator is particularly important This article introduces the working principle of generators, focusing on common faults and maintenance of generators, and proposes simple and feasible detection methods based on the characteristics and current development status of electrical systems

Keywords: Automotive Generators, Working Principles of Alternators, Fault Detection

First, Working Principles of Alternators

(1) Power Generation Principle E=C n (E is proportional to n and)

(2) Rectification Principle

(1) At any moment, only one positive diode and one negative diode are conductive, and the positive and negative diodes will not be two in the same bridge

(III) Excitation method

(1) Other excitation

(2) Self excitation

(II) Working characteristics of the AC generator

(I) No-load characteristics can determine whether the low-speed charging performance of the generator is good from the no-load characteristics.

(2) Output characteristics

2. It has the ability to limit the output current (3) External characteristics

(1) The voltage of the generator is greatly affected by changes in speed and load, and a voltage regulator must be equipped (2) When the generator is rotating at high speed, avoid significant load reduction

III. Fault Analysis and Detection of Generators

(1) The main reasons for generator failure to generate electricity are: rectifier diodes, short circuits or open circuits; Excitation winding open circuit or open circuit; Short circuit or grounding between three-phase stator windings; The rotor slip ring is severely oxidized and dirty, the carbon brush holder is damaged, or the carbon brush is stuck in the brush holder When it is suspected that the generator has a malfunction, preliminary testing can be carried out on the vehicle, and further testing can be carried out without disassembling the generator. The tools used for testing can be a multimeter, a general DC voltmeter, a DC ammeter, and an oscilloscope. They can also use car bulbs, flashlight bulbs, and homemade small test lights. They can also be tested by changing the working state of the car

On vehicle detection method: When it is suspected that the generator does not generate electricity, it can be tested on the vehicle without disassembling it to roughly determine whether there is a fault

(1) Multimeter voltage range detection

(2) External ammeter detection When there is no ammeter on the car dashboard, an external DC ammeter can be used for detection.

. First, remove the generator's "armature" terminal wire, and then connect the positive pole of the DC ammeter with a measuring range of about 20A to the generator's "armature", and the negative pole wire to the above removed connector. When the engine is running at medium speed or above and no other electrical equipment is used, the ammeter has a 3A~5A charging indication, indicating that the generator is working normally. Otherwise, the generator will not generate electricity (3) When there is no multimeter or DC meter available, a car light bulb can be used as a test light to detect. Weld the appropriate length of wire at both ends of the light bulb and connect a fish clip at both ends. Before testing, first remove the wire of the generator's "armature" terminal, and then clamp one end of the test light onto the generator's "armature" terminal, while the other end is grounded. When the engine is running at medium speed, the brightness of the test light indicates that the generator is working normally, otherwise the generator will not generate electricity