Progress and recent trends in 48V hybridisation and e-boosting technology on passenger vehicles - a review

Electrification of the powertrain system will play an important role in reducing fuel consumption and engine-out emissions in the next few decades. Compared to the pure electric and full hybrid concept, 48V mild hybridisation and the accompanying 48V e-boosting concept, due to their superior cost-benefit performance, may become mainstream for the next generation of fuel reduction measures. The mild hybrid system can realise advanced stop-start, active and passive engine-off coasting, braking recuperation, boost assistance, e-creeping and torque vectoring functions, and is thus deemed to give approximately 10-15% fuel consumption benefits in the New European Driving Cycle (NEDC); and the e-boosting concept, due to its capability for further downsizing and down-speeding, allows the engine operating points to be shifted into a more efficient area. A strong synergy between 48V mild hybridisation and the 48V e-boosting concept has been found after reviewing both technologies, and the trends for developing such a combined electrical system are also discussed. Together with more engine and vehicle component electrification, fuel efficiency could be further improved, although the interactions between these technologies are highly complex and need to be optimised at a system level.