I01�High-voltage�Components
6.�Charging�the�High-voltage�Battery
127
For�DC�charging�the�LIM�closes�the�two�switch�contactors�in�the�KLE,�thus�enabling�the�shift�through
from�the�direct�current�voltage�from�the�DC�charging�station�to�the�high-voltage�battery.�The�LIM�tests
after�every�completed�DC�charging�procedure�the�DC�switch�contactors�so�that�a�switch�contactor
label�(switch�contactor�cannot�open�the�contacts)�is�identified.�A�switch�contactor�label�(single�or
double)�is�identified�by�the�LIM�and�sent�to�the�EME�as�a�fault�code.�If�during�the�charging�procedure
no�valid�pilot�signal�is�identified�by�the�LIM,�the�LIM�must�open�the�DC�switch�contactors�within
200 ms.
The�direct�current�voltage�applied�at�the�charging�socket�is�measured�by�the�KLE.�The�measured�value
is�then�sent�to�the�LIM�as�an�analog�signal.�The�LIM�then�sends�the�calculated�value�via�PT-CAN�to
other�control�units.
Emergency�charging
If�both�the�high-voltage�and�the�12 V�battery�are�discharged,�the�emergency�charging�of�the�12 V
battery�is�automatically�started�when�the�charging�cable�is�connected.�As�the�two�batteries�are
discharged,�there�is�also�no�voltage�supply�of�the�12 V�vehicle�electrical�system�and�the�LIM�is�in�this
case�initially�not�working.�So�that�the�LIM�can�start�communication�with�the�charging�station�and�thus
also�the�charging�procedures,�a�special�voltage�supply�of�the�LIM�is�required.�The�voltage�supply�for
the�LIM�is�effected�in�this�case�by�the�pilot�line.�The�energy�used�by�the�pilot�line�is�so�low�that�the
voltage�evaluation�for�the�EVSE�is�not�affected.
In�order�to�identify�emergency�charging�the�voltage�value�of�terminal�30F�is�evaluated.�The�evaluation
circuit�is�located�in�the�LIM.�If�the�voltage�value�of�terminal�30F�falls�below�6 V�and�the�pilot�line�is
correctly�connected,�the�evaluation�circuit�drags�the�voltage�value�on�the�pilot�line�to�a�value�of�6 V.
This�voltage�value�corresponds�to�the�message�at�the�charging�station�that�the�vehicle�is�ready�for
charging.�The�charging�station�is�thus�prompted�to�apply�the�vehicle�voltage.
6.4.4.�Convenience�charging�electronics�(KLE)
Convenience�charging�electronics�for�combo�charging�at�7.4 kW�AC�charging�power
The�KLE�version�installed�for�combo�charging�at�7.4 kW�AC�charging�power�is�responsible�for�the
contact�of�all�HV�connections�and�the�housing�of�the�two�DC�switch�contactors.
In�this�case�the�KLE�has�
no
�rectifier�switching�for�the�conversion�of�AC�voltage�to�direct�current
voltage.�The�conversion�of�the�AC�voltage�to�direct�current�voltage�takes�place�in�the�charging�station.
The�full�power�of�the�AC�network�is�used�(all�three�phases).�If�all�prerequisites�for�charging�the�high-
voltage�battery�are�satisfied,�the�LIM�switches�on�the�two�switch�contactors�in�the�KLE.�The�charging
station�then�provides�the�direct�current�voltage�at�the�output�for�charging�the�high-voltage�battery.�The
direct�current�voltage�reaches�the�KLE�via�the�charging�socket�and�the�high-voltage�cables.�The�direct
current�voltage�is�directed�via�the�high-voltage�cables�to�the�EME�and�then�finally�to�the�high-voltage
battery.�The�high-voltage�cables�and�the�switch�contactors�are�designed�for�an�electrical�power�of�up
to�50 kW.
