Charging unit 1 for high-voltage battery AX4
When charging with alternating current, the charging voltage for the Audi e-tron GT first needs to be converted into direct-current
(DC) voltage. The high-voltage battery cannot receive AC voltage. This is done using the high-voltage charger, which has a power
rating of 11 kW (standard version). The number refers to the electric input power of the high-voltage charger. The high-voltage
charger also contains the charging management system.
The charger is fitted centrally in the front part of the vehicle.
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The input circuit (1) on the mains supply side contains mains filters to suppress interference from and in the mains supply (these
are required by law). The rectifier bridge circuit (2) after the mains filter passively converts the alternating-current voltage (AC)
from the mains supply to direct-current voltage (DC). The step-up converter (3) directly downstream from this keeps the intermedi-
ate circuit voltage in the downstream intermediate circuit capacitor (4) at a constant 400 Volts DC during the charging process in
order to provide the energy for the H-bridge driver circuit (5). The H-bridge driver circuit (5) converts the direct-current volt-
age (400 Volts) to a square-wave alternating-current voltage (AC) with 100 kHz. This is necessary so that the energy can be trans-
ferred via the isolating transformer. The isolating transformer (6) downstream from this galvanically isolates the AC mains supply
from the high-voltage electrical system of the vehicle (DC). To rectify the voltage, a full bridge rectifier (7) is positioned down-
stream of the output side of the isolating transformer (6). A capacitor (8) positioned after the rectifier serves to smooth and buffer
the current.
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