Separate Operation Of Secondary 12 V On-Board Electrical System, Basic Function - GF54.10-P-1017A
Model All (CAR)
Overview
This document contains information on:
- General
- Function
- Normal mode
- Separate operation
General
The functions of the highly automated parking or driving system automatically take over the driving tasks of the driver. This increases the demands on the electrical energy supply in terms of safety and availability. Single errors must not result in uncontrollable system failure. To achieve this objective, the regular 12 V on-board electrical system is extended to include a secondary 12 V on-board electrical system. Electrical components which are relevant for driving safety are connected in parallel to both networks. In normal operation, these system-relevant consumers are supplied from the 12 V on-board electrical system. The secondary 12 V on-board electrical system is kept operational as a standby system.
If the 12 V on-board electrical system fails, the system-relevant consumers are supplied via the secondary 12 V on-board electrical system. This is supplied from the auxiliary battery of the secondary 12 V on-board electrical system. Thus, functions that are required for highly automated parking or driving are maintained for a defined period of time. The vehicle can be secured either automatically or by means of a driver intervention.
Function
Normal mode
In normal operation, the DC/DC converter for the secondary 12 V onboard electrical system sets up the connection between the 12 V onboard electrical system and the secondary 12 V on-board electrical system. It ensures that the charge of the auxiliary battery for the secondary 12 V on-board electrical system is maintained. A current flow from the 12 V on-board electrical system to the secondary 12 V on-board electrical system is permitted. However, a current flow in the other direction is blocked because the secondary 12 V on-board electrical system is provided at an increased voltage.
Separate operation
If the following events occur, the DC/DC converter disconnects the connection between the 12 V on-board electrical system and the secondary 12 V on-board electrical system by means of an internal separator:
- The voltage at circuit 30t drops below a minimum value.
- A serious fault occurs in the 12 V on-board electrical system.
- Failure of the 12 V on-board electrical system.
During disconnected operation, the secondary 12 V on-board electrical system is fully operational. The system-relevant consumers are further supplied by the auxiliary battery of the secondary 12 V on-board electrical system for approx. 1 minute.
The system-relevant consumers include:
- the Electronic Stability Program control unit,
- the power steering control unit,
- the parking system control unit,
- control units used for position determination.
| Additional basic functions | |||
|---|---|---|---|
| Secondary 12 V on-board electrical system DC/DC converter control unit, basic function | GF54.10-P-2019A | ||
| Secondary 12 V on-board electrical system battery, basic function | GF54.10-P-2020A | ||
| Component descriptions | |||
| Component description for on-board electrical system battery | Model 223 | GF54.10-P-2007A | |
| Component description for DC/DC converter control unit | Model 223 | GF54.10-P-3006A |