The powertrain industry is now driven by regulations on emissions and CO_2 with challenging targets for 2020-2025 timeframe. Despite huge progresses still expected on Internal Combustion Engines, there is no chance to reach the global targets without several levels of hybridization, which allows energy recovery from braking. Hybrid vehicles demonstrated significant CO_2 emissions reduction but remain complex and expensive, mostly due to batteries cost and high voltage network. Lowering hybrids cost is a necessity and mild hybrid 48 volts is an interesting compromise in terms of cost/benefits ratio. Among the various hybridization levels, the 12+12 volts affordable architecture represents the basic architecture allowing the benefits of hybridization, thanks to the energy recovery during braking. The 12+12volts electrical architecture is based on 2 batteries which are supplied or could supply electric power in 12V voltage. This architecture should be also modular in order to address different functionalities with various components. 12V systems have lowest cost for first hybrid functions and make a sense on B/C segment. 48V systems are opportunity to address more CO_2 reduction through well known hybrid functions. From this point of view, a continuous road map seems to appear between 12V Stop&Start systems, 48V hybrids and beyond. As a matter of fact, extended Stop&Start thanks to regenerative braking and coasting functions can be managed under 12V while 48V systems appears with a real potential of further evolution with complementary functions and higher power components. A focus on 48V world identifies this new path for hybridization and alternative hybrid systems due to the power level achievable and the energy capacity storage. This new system extends the 48V hybrid road map and allows addressing CO_2 gains similar as Full hybrid systems which are usually high voltage systems. The communalities between the 12V+12V and 48V electrical architecture will be presented to identify the similar functions repartition and plug & play opportunities. In addition, 48V electrical architecture can be an opportunity to raise current limit in board net components and allows the electrification of high power functions with optimization and power on demand facilities. By this way, comfort and safety features can be electrified. Linked to the hybrid architecture, this opens the way to beltless engines and to enhance hybridization CO_2 reduction and powertrain efficiency.
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