GF15.40-P-0001MCU On-Board Electrical System Power Supply, Function

GF15.40-P-0001MCU On-Board Electrical System Power Supply, Function







1 Requirement on alternator charge monitoring and warning lamp
2 Vehicle power supply voltage
3 Charging current
4 Alternator load condition
5 Engine control, request
A1 Instrument cluster
A1e5 Alternator charge monitoring and warning lamp
G1 Battery
G2 Alternator
N3/10 ME-SFI [ME] control unit
CAN Controller Area Network (data bus/CAN bus) (CAN)

General
When the engine is running, the alternator supplies the on-board electrical system with electrical energy and charges the battery. For this purpose, the alternator generates three-phase current which is rectified.

Function
The power supply for the on-board electrical system is monitored and regulated by the ME-SFI [ME] control unit.
For circuit 15 On voltage is applied to connector D+ of the alternator.
However as long as no charging voltage is recognized by the ME- SFI [ME] control unit, it requests switching on of the charge control and alternator warning lamp via the CAN.
After starting the engine, the alternator produces the preexcitation current itself. The alternator delivers current via connector B+ to the battery and to the on-board electrical system. The alternator voltage lies slightly under the gassing voltage of the battery which achieves adequate charging and prevents damage to the battery through overcharging.

The ME-SFI [ME] control unit then switches off the request to the charge control and warning lamp.
If the on-board power supply voltage is less than 11.5 V for longer than 3 minutes, a signal is sent to the instrument cluster via the CAN to switch on the charge control and warning lamp.

Control
The alternator is regulated by the integral electronics depending on the:
^ Rpm
^ Vehicle power supply voltage
^ Request from the ME-SFI [ME] control unit
^ Ambient temperature

The status of the momentary operating rate of the alternator is monitored by the ME-SFI [ME] control unit. The regulating voltage in neutral is 13.5 V and for a maximum engine speed a\\bout 14.5 V.

The alternator is connected directly with the ME-SFI [ME] control unit.

The following functions are implemented:
^ Preexcitation
^ Feedback of the alternator load
^ Voltage demand by the ME-SFI [ME] control unit