48-Volt Electrical System.
1. Introduction.
The BMW Group has for years been developing a variety of technologies to reduce the overall CO2 fleet consumption. Among these technologies are micro-hybrids, in which the measures of EfficientDynamics are implemented. Another important milestone was the development of plug-in hybrids (PHEVs) and battery electric vehicles (BEVs). Now we are witnessing the development of mild hybrid technology.
The 48-Volt System is being introduced in the G30 with the BMW 540i and 540ix as of July 2020 tobe followed by G20 with the BMW 340i and 340ix. The 48-Volt System will be included on all future vehicles equipped with a B58 engine. The new 48-Volt system will also deliver new functions whichserve to increase comfort, efficiency and dynamics.
The introduction of mild hybrid technology produces new functions with noticeable customer benefits:
• Reduced CO2 emissions
Braking energy is not lost, but instead electrically recuperated. The combustion engine is supported in driving mode and operated in more efficient operating conditions. This results in consumption reductions in customer operation of around 0.3 l/100 km.
• Improved automatic engine start/stop function (MSA)
The powerful 48-volt starter motor generator produces a noticeable improvement in starting time of approximately 20% faster to improved comfort in terms of acoustics and vibrations during the starting procedure. The starting procedures are now barely noticeable. The first engine start of the day is done by the conventional 12 volt pinion starter motor. If the engine temperature is greater than 60 °C (140°F), the engine will be started by the 48-volt starter motor generator.
• Engine off coasting
In so-called "coasting" the combustion engine in normal situations no longer continues to run at idle in mild hybrid vehicles, but is instead switched off completely and the drivetrain is decoupled in order to utilize the vehicle's kinetic energy for motion. Compared with the idle coasting function the consumption advantage can be further increased by switching the combustion engine off. Restarting is virtually delay-free thanks to the powerful 48-volt starter motor generator.
• Dynamics advantage thanks to eBOOST function
In partial load operation the starter motor generator supports the combustion engine as an electricalmachine. Thanks to its delay-free power output, the electrical machine improves the acceleration build-up, i.e. the spontaneity of the drive. In response to full load demand the electrical machine can incertain operating ranges briefly increase the drive's overall power by 8 kW (10 hp).