Generator Principle Diagram The working principle and structure of the generator
1 The composition of the alternator:
It is generally composed of rotor assembly, stator assembly, rectifier assembly, end cover, pulley, fan, etc.
1 – Rear end cover 2, 3, 4 – Carbon brush and carbon brush holder 5 – Rectifier plate 6 – Diode
7 – Rotor 8 – Stator assembly 9 – front end cover 10 – fan 11 – pulley
(1) Rotor assembly: The function of the rotor is to generate a rotating magnetic field.
The rotor consists of claw poles, magnetic yokes, magnetic field windings, conductive slip rings, and rotor shafts:
1 – conductive slip rings 2 – rotor shaft 3 – claw poles 4 – magnetic yoke 5-Field winding
Two claw poles are press-fitted on the rotor shaft, and each of the two claw poles has six bird’s beak-shaped magnetic poles. There are field windings (rotor coils) and yokes.
The conductive slip ring is composed of two copper rings insulated from each other. The conductive slip ring is press-fitted on the rotor shaft and insulated from the shaft. The two conductive slip rings are respectively connected to both ends of the field winding.
When the two-conductor slip ring is fed with direct current through the carbon brush, current flows through the magnetic field winding, and an axial magnetic field is generated. When the rotor shaft of the generator rotates under the drive of the engine, the magnetic field is synchronized. rotate.
(2) Stator: The function of the stator is to generate three-phase alternating current.
The stator consists of a stator core and stator windings:
The stator core consists of silicon steel with grooves in the inner ring The sheets are stacked, and the conductors of the stator windings are embedded in the slots of the iron core.
The stator winding has three coils, also known as three-phase windings. The three coils are connected in star connection (Y connection) or delta connection, which can generate three-phase alternating current.
Three-phase winding star connection:
star Connection method
The star connection method is used in most of the generators of the car. The common end of the three coils is called the neutral point, which is represented by N. The neutral point N is often used to control the charging indication system.
Delta connection of three-phase windings:
Delta connection
For delta connection It is beneficial to improve the output power of the generator.
The three-phase windings must be wound according to certain requirements, in order to obtain the three-phase electromotive force with the same frequency, the same amplitude and the phase difference of 120°.
(3) Rectifier: The output of the three-phase winding of the generator is three-phase alternating current, while the direct current used in the automobile power system has a rectifier inside the generator to convert the alternating current into direct current output . The principle and structure of the rectifier will be introduced in detail in the following chapters.
2 How an alternator produces three-phase alternating current:
Stator and rotor diagram of generator
(1) The rotor coil must be energized to generate a magnetic field: the rotor coil is powered by the F and E terminals, and the rotor coil is energized to generate a magnetic field;
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(2) The engine works to drive the rotor to rotate: that is, the magnetic field rotates, the stator coil cuts the magnetic field lines, and alternating current is generated in the stator coil. Due to the arrangement of the three stator coils, the phases of the alternating current generated by the three coils are staggered by 120 degrees, which is called three-phase alternating current.
(3) The amplitude of the AC voltage output by the stator coil increases in proportion to the speed of the generator. The regulator regulates the magnitude of the energized current of the rotor coil to control the output voltage of the generator.
