High-voltage system energy management in charge mode, function

P08.00-2038-81

Function requirements, general

 Charging cable inserted and locked

 The status charging cable inserted is recognized over the "Proximity contact" on the charger feed socket and the associated "Proximity line" in the charging cable. If both connectors (on the vehicle and on the charge socket) are inserted correctly the onboard charger recognizes the "Proximity contact" and transmits the signal "Proximity recognized" over the electric vehicle CAN. All involved control units are awakened and the charging cable is locked. Actuation for locking or unlocking of the charging cable takes place over a direct line by the onboard charger. The onboard charger reads in the status charging cable locked over a direct line.

High-voltage system energy management in charging mode, general points

The high-voltage system energy management in charging mode secures charging of the high-voltage battery (G5). A charging process for the high-voltage battery which is as sparingly as possible but at the same time quicker is sought.

The whole charging process takes place monitored. The onboard charger and the energy source (charging station) communicate over a data line in the charging cable (Control Pilot). For charging processes at a conventional household socket the communication occurs between the onboard charger and a control box installed in the charging cable. The performance data about the charging infrastructure is sent in the process and the power consumption of the onboard charger is adapted appropriately. Furthermore the signals "ready", "not ready" and "charge" are transmitted. The indicator lamps on the charger feed socket are actuated according to the respectively transmitted signal. As first the onboard charger initiates the charging process.

 During charging at a household socket the charging current must be limited if necessary so as not to overload the internal power network in the house. The maximum permissible charging current can therefore be set over the respective menu in the IC (A1) or the control box in the charging cable.

The following control units and components are involved in the charging process and in the monitoring:

 Battery management system control unit

 3kW onboard charger (without code (908) 22KW onboard charger)

 Powerline Gateway control unit (without code (908) 22KW onboard charger)

 22kW onboard charger (for code (908) 22KW onboard charger)

 Electric vehicle communications module control unit (for code (B54) COM-MODULE (traffic data and condition of the battery))

 Drivetrain control unit

 Power electronics control unit

 Charger feed-in socket

 The Powerline Gateway control unit is only installed in 3kW onboard charger (without code (908) 22KW onboard charger). This function of the Powerline Gateway control unit is integrated into the electronics 22kW onboard charger for the 22kW onboard charger (for code (908) onboard charger 22KW).

The high-voltage system energy management charging mode function comprises the following partial functions:

 Function sequence for determination of the charge level and chargeability

 Function sequence for charging over the charging cable

 Function sequence for communication with the charging station

Function sequence for determination of the charge level and chargeability

In order to keep the charging time of the high-voltage battery as low as possible the charge level and the chargeability are determined. The chargeability of the high-voltage battery is primarily dependent on the respective temperature of the high-voltage battery.

 Information for thermal management of the high-voltage battery is received in the separate function "thermal management function".

The charge level of the high-voltage battery is crucial for the charging time. For complete use of the capacity of the respective onboard charger the charging time is:

 3kW onboard charger (without code (908) 22KW onboard charger):

Charging period 8 h from 0 to 100% high-voltage battery charge status and 4 h from 20 to 80% high-voltage battery charge status.

 22kW onboard charger (for code (908) 22KW onboard charger)

1 h from 0 to 100% high-voltage battery charge status and 0.5 h from 20 to 80% high-voltage battery charge status.

The following control units are involved in determination of the charge level and the chargeability:

 Battery management system control unit

 onboard charger

 Drivetrain control unit

The following signals from the battery management system control unit are read in by the drivetrain control unit via the electric vehicle CAN:

 high-voltage battery voltage

 high-voltage battery current

 temperature of high-voltage battery

 high-voltage battery charge level

 High-voltage battery, status

The following signals from the onboard charger are read in by the drivetrain control unit via the electric vehicle CAN:

 proximity recognition

 Control pilot, status

Function sequence for charging over the charging cable

In charging mode AC voltage is fed to the onboard charger over the charger feed power outlet. The AC voltage for the 3kW onboard charger is 100 to 240 V and for the 22kW onboard charger is 3  400 V. The respective onboard charger converts the incoming AC voltage into a direct voltage and leads this over the safety box high voltage adapter plate for the high-voltage battery. The output voltage at the respective onboard charger is about 380 V.

The following control units are involved in monitoring and controlling the charging process:

 Battery management system control unit

 onboard charger

 Electric vehicle communications module control unit

 Drivetrain control unit

The following signals from the onboard charger are read in over the electric vehicle CAN by the battery management system control unit:

 charging voltage

 Charging current

 onboard charger, status

The following signals from the battery management system control unit are read in by the drivetrain control unit via the electric vehicle CAN:

 charging voltage

 charging current

The following signals from the onboard charger are read in by the drivetrain control unit via the electric vehicle CAN:

 charging voltage

 charging current

 onboard charger, status

 onboard charger input voltage

 onboard charger input current

 maximum possible charging current

 number of input phases

Function sequence for communication with the charging station

The whole charging process takes place monitored. The onboard charger and the energy source (charging station) communicate over a data line in the charging cable (Control Pilot).

For intelligent charging stations there is also digital communication over the powerline (Powerline Communication) on the lines L1 and N. Data are transmitted according to the record specified in ISO/IEC 15118 to do this. For vehicles without code (908) 22KW onboard charger this communication takes place over the Powerline Gateway control unit. This function of the des Powerline Gateway control unit for the 22KW (for code (908) 22KW ) onboard charger is integrated into the electronics of the 22kW onboard charger.

The communication with the charging station serves:

 reciprocal authentication of the vehicle and charging station

 checking the contract data

 automatic cost settlement of the power costs

The charging station supplies data about the availability of power as well as tariff information. This information is evaluated by the vehicle and used for optimal charging of the high-voltage battery. The power costs are calculated/invoiced automatically just as soon as the charging process has stopped.

Apart from communication with the intelligent charging station it is also possible for a connection to be made with internet on the "Vehicle Homepage". This is possible over the power supply network (Powerline Communication) and for vehicles with code (B54) COM-MODULE (traffic data and battery status) over the mobile telephone network. Establishment of the connection and the communication over the mobile telephone network takes place by the electric vehicle communications module control unit. The electric vehicle communications module control unit uses GSM (Global System Mobile) and transmits all necessary data over radio. The vehicle automatically recognizes whether a connection is possible with the internet over the electric vehicle communications module control unit or not.

Access can be gained to the following functions over the "Vehicle Homepage":

 inquiry of the current charge level

 programming the departure time

 activation of the preclimatization function

The electric vehicle communications module control unit reads in the following data for this over the electric vehicle-CAN which are transmitted from the drivetrain control unit:

 status information concerning the preclimatization

 period up to departure

 relative time up to full charging

 information concerning the charging process

 information concerning the range

The electric vehicle communications module control unit transmits the following data via the electr. vehicle-CAN to the drivetrain control unit:

 internet connection is available

 default settings for the preclimatization

 point in time of departure