ISSUE 012 Winter 2021 Sigma Powertrain EMAX transmission dossier l In conversation: David Hudson l 48 V systems focus l 2021 Battery Show North America and Cenex-LCV reports l Everrati Porsche 911 digest l Switching insight l Motor laminations focus

Moving to power distribution networks running on 48 V looks set to confer a range of bene its to battery-electric vehicles. Nick Flaherty reports Potential di erence T echnology based on 48 V has been adopted for electric motors and battery packs to reduce emissions in mild hybrid vehicles, but changing regulations are seeing even those being banned from as early as 2030. This leaves mild hybrids with a limited window for development, which is driving a more modular approach to the development of the powertrain technology for use in wider applications, from two- and three-wheelers to off- road construction equipment. At the same time, the high volume of hybrid production has driven down the cost of 48 V motors and battery packs, opening up the other applications. Moving some parts of the powertrain to 48 V is also highlighting the advantages in other parts of the vehicle of direct 48 V operation, such as heating and air conditioning. This in turn has driven the development of local DC-DC converters and passive components such as capacitors and inductors suitable for 48 V designs that could see the technology being adopted in full battery-electric designs, converting the 400 or 800 V output of the battery pack to 48 V for distribution around the vehicle. The advantage of a 48 V power distribution network to replace legacy 12 V systems is more significant when much higher currents are flowing. Supported by DC-DC converters that can provide the 48 V supply, the move to 48 V can cut the size and weight of the cable harness dramatically, as a 48 V cable is half the diameter of a 12 V one. This supports existing 48 V DC-DC converter designs that will drive 12 V subsystems, and also opens up point-of-load (PoL) designs for supplying increasingly power-hungry ECUs handling ADAS safety systems and even the central controllers for autonomous driving in full battery- electric vehicles. Mild hybrid designs Mild hybrids make conventional IC engines much more efficient thanks to a relatively simple upgrade that can include recovering kinetic energy from braking. This energy is stored in a relatively small 48 V battery, typically up to 1 kWh, and used to support a 48 V motor that handles start-stop operation. This cuts fuel consumption by 15% or more, and thus reduces CO 2 emissions accordingly. In the simplest arrangement, called P0, the conventional 12 V generator is replaced directly by a 48 V machine, This 48 V battery system from Varta is powering an electric scooter (Courtesy of Continental) 32 Winter 2021 | E-Mobility Engineering