Development work for the 48 V electrical system for electric vehicles (EV) and hybrid electric vehicles (HEV) has been ongoing since 2010. The 48 V on-board network is not intended to replace the 12 V on-board network, but to supplement it, as many proven 12 V components are also used in the combined on-board networks
. On-board networks with 48 V supply voltage are more cost-efficient than the classic 12 V on-board networks. Thanks to the higher supply voltage, electric drive units, motors, seat heaters, air-conditioning compressors and other powerful components with outputs of several kilowatts can be supplied. The 48 V supply voltage reduces the high currents of
a 12 V supply inrelation to a 12 V supply, thus reducing the cable cross-section and the weight of the cables
. Since this concept also relies on proven 12 V components, the 48 V architecture uses bidirectionalDC/DC converters that convert the 48 V of the lithium-ion battery to 12 V and the 12 V of the lead-acid battery to 48 V. The 48 V supply voltage is also used for the power supply of a hybrid electric vehicle. In hybrid electric vehicles, the 48 V on-board voltage that drives the electric motor can be generated by a generator connected downstream of the combustion engine or by energy recovery, recuperation, during braking. The battery charge is controlled by a battery management system (BMS). Especially for electric vehicles, there are high-voltage electrical systems with supply voltages of 400 V for electric drive units with outputs of several hundred kilowatts and with currents of several hundred amperes.