Automotive supplier Continental has been working with Renault since 2013 on a mild hybrid system that operates at 48 volts, instead of the 300-400 volts usually used in hybrid vehicles. The new Hybrid Assist system is slated to go into production in Renault’s new Scénic and Grand Scénic models.
Instead of a conventional starter generator, the system uses an electric motor with a continuous output of 6 kW (10 kW temporary). The motor is also used to recapture braking energy, which is stored in a small battery. The combustion engine can be switched off at speeds below 20 km/h, and restarted with the 48-volt drive within 0.2 seconds – half the time required by a conventional starter.
In test vehicles, Continental’s 48-volt technology has demonstrated fuel savings of up to 21 percent.
The 48-volt solution is designed to be easy to combine with existing ICEs, and requires no more room than a conventional starter generator. The water-cooled induction motor can be connected directly to the engine’s cooling circuit. The inverter is integrated into the housing lid of the motor, and the modular system also includes a DC/DC converter, which enables the 48-volt system to be connected to the vehicle’s on-board power supply.
Continental anticipates rapid market penetration. It predicts that, in 2020, four million vehicles with low-voltage hybrid drives will be produced worldwide, and that by 2025, one in five new vehicles will be equipped with a 48-volt drive.