Alternator: Description and Operation

Generator

OVERVIEW
A single self-exciting generator is located at the front of the engine on the LH (left-hand) side of the cylinder block. There is one generator available for the petrol engines. The generator is rated at 180 amps.
The generator pulley incorporates a one-way clutch that reduces NVH (noise, vibration and harshness), and improves the life of the accessory drive belt. The one-way clutch allows the belt to drive the pulley without slip occurring, but prevents the generator from driving the belt during transients in engine speed ('belt whip') due to the high rotational inertia of the generator internal components.
The generator comprises the following major components:
- Stator
- Rotor
- Rectifier pack
- Regulator.
The stator consists of a flat core pack into which the stator wires are pressed.
The rotor comprises a field winding, wound around an iron core and mounted on a shaft. The rotor is housed within the stator and mounted on bearings to provide smooth running and support, due to the side loading applied by the drive belt tension.
The rectifier contains 6 pairs of diodes (six on the positive plate and six on the negative plate) mounted on a heat sink. The heat sink dissipates the resultant heat created in the electrical conversion process. The rectifier converts the AC (alternating current) produced in the stator coils into DC (direct current) that is required by the vehicle electrical system.
The regulator provides a controlled variable voltage output from the generator. Two electrical terminals are provided on the outer casing of the generator. B+ terminal supplies the rectified and regulated DC (direct current) from the generator, via a large diameter cable to the battery positive terminal. The second terminal provides the LIN (local interconnect network) bus connection between the regulator and the ECM (engine control module).
The regulator is connected via LIN (local interconnect network) bus to the ECM (engine control module), the ECM (engine control module) is also connected via the high speed CAN (controller area network) bus to the BCM (Body Control Module). The BCM receives information from the BMS regarding battery conditions. The BCM uses the information from the BMS to set the target voltage via high speed CAN (controller area network) to the ECM (engine control module), then the ECM (engine control module) sends it via LIN (local interconnect network) to the alternator.
The LIN (local interconnect network) bus is also used to communicate a mechanical failure, or fault in the wiring and connections from the generator to the ECM (engine control module). A DTC (diagnostic trouble code) is stored in the ECM (engine control module) and if necessary, the charge warning indicator lamp is illuminated in the instrument cluster after a short delay.
During engine starting the charge warning indicator lamp is illuminated in the instrument cluster when the ignition is energized, and is extinguished when the engine starts and the ECM (engine control module) detects a generator output voltage.