48 V on-board power

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. The higher supply voltage means that 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 in relation to a 12 V supply, thus reducing the cable cross-section and the weight of the cables.

Because this concept also relies on proven 12-V components, the 48-V architecture uses bidirectional DC/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. 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. Battery charging is controlled by a battery management system( BMS). Specifically for electric vehicles, there are high-voltage vehicle 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.