BMW:The first fully electric BMW xDrive system in the BMW iX and the BMW i4 M50
Faster, more precise, more efficient: The first fully electric
BMW xDrive system in the BMW iX and the BMW i4 M50.
Two engines, four driven wheels and a globally unique drive torque
control system ensure optimal traction, driving stability and dynamics
in every situation.
Munich. More than 35 years ago, all-wheel drive
provided a new form of driving pleasure for the first time in a BMW,
and the intelligent distribution of power between the front and rear
axles has been known as BMW xDrive for almost two decades. The
fascination of four driven wheels now reaches an additional,
particularly sustainable dimension. The first fully electric BMW
xDrive system can now be experienced on the road. It makes its debut
in the BMW iX and the BMW i4 M50 (combined power consumption:
22.5 – 18.0 kWh/100 km according to WLTP; combined CO2
emissions: 0 g/km).
Like all BMW iX vehicle types, the fully electric Gran Coupé from BMW
M GmbH is powered by an engine on both the front and rear axles. This
creates an axle-parallel all-wheel drive without a mechanical
connection between the front and rear wheels. The interaction of the
two engines is optimised by an innovative and globally unique drive
torque control system. The electric BMW xDrive system thus ensures the
ideal form of power transmission in every driving situation – combined
with a typical BMW driving experience.
Intelligent networking of driving stability control, actuator
contiguous wheel slip limitation and drive control.
The fully electric BMW xDrive system makes it possible to transform
outstanding drive power, expressed for example in the BMW i4 M50 with
a system output of up to 400 kW/544 hp and a maximum torque of 795 Nm,
into superior driving dynamics. This requires precise distribution of
the drive torque. This is ensured by linking the DSC (driving
stability control) system with the all-wheel drive-specific version of
the actuator contiguous wheel slip limitation and the Combined
Charging Unit (CCU), whose highly integrated range of functions for
the first time includes both charging and drive electronics.
The intelligent networking of all systems makes it possible to
distribute the drive torque requested by the driver between the two
engines in such a way that traction and driving stability, dynamics
and efficiency are guaranteed to an optimum extent in the respective
driving situation. DSC defines the general conditions under which the
electric BMW xDrive system can operate. It permanently analyses the
vehicle’s wheel speeds, steering angle, driving speed, longitudinal
and lateral acceleration and yaw rate. Based on these parameters, a
speed corridor is determined in which the two drive units may be
active to ensure a stable driving condition. The My Mode selected by
the driver and whether the DTC (Dynamic Traction Control) is activated
are also taken into account. This mode is a special DSC mode in which,
in interaction with actuator contiguous wheel slip limitation and
other control functions, an even sportier driving style is possible on
normal surfaces without interventions, among other things through
increased intervention thresholds. In addition, a maximum drive is
achieved on loose ground such as snow, sand or gravel.
From the data supplied by DSC and the drive torque requested by the
driver, the CCU calculates the ideal distribution between front and
rear-wheel drive. The fully electric xDrive system can react
noticeably faster and with significantly higher control quality to any
change in driving situation than would be possible with a transfer box
between the axles familiar from BMW models with combustion engines.
The drive control of the CCU, actuator contiguous wheel slip
limitation and the driving stability control system interact flexibly
and precisely. If required, the data supplied by DSC about the driving
situation can already proactively include an all-wheel drive request.
In many driving situations, a change in the distribution of drive
torque between the front and rear engines alone can increase driving
stability without requiring any further intervention. If one wheel
threatens to lose grip with the road surface, actuator contiguous
wheel slip limitation with its particularly fast and precise reactions
comes into play first. Only in critical situations does DSC also
assist with wheel-specific braking interventions.
Optimal traction, perfect directional stability, maximum efficiency.
During driving off and accelerating, the desired drive torque is
distributed between both engines by the CCU to provide optimised
traction. In addition to the road friction values and the driver’s
choice, the electric BMW xDrive and actuator contiguous wheel slip
limitation also take into account environmental parameters such as
wind, uphill or downhill gradients, the vehicle settings of the My
Modes and the DTC, as well as the dynamic axle-load distribution,
which provides more weight and better power transmission to the rear
axle during acceleration. Due to the direct integration of actuator
contiguous wheel slip limitation into the drive torque control system
of the CCU, long signal paths to the driving stability control system
are eliminated, meaning that interventions can be performed at a speed
that is up to 10 times higher and in a particularly precise dosage.
This ensures unwavering directional stability of the vehicle even
during extremely dynamic acceleration manoeuvres.
When the accelerator pedal is pressed moderately, a continuously
higher proportion of drive torque is provided by the rear electric
drive unit as the speed increases. In phases of constant driving, the
drive is finally provided solely by the engine acting on the rear
wheels. This creates the traditional BMW driving experience. At the
same time, the efficiency of the drive system and, with it, the range
of the vehicle is optimised.
Full all-wheel drive functionality is available at all times. For
example, even when driving in My Mode Efficient, any spontaneous load
demand is immediately met with a significant increase in drive torque
on the front axle. When cornering dynamically, on the other hand, the
proportion of rear-wheel drive is increased. The front wheels can
therefore absorb higher cornering forces due to the reduced drive
torque. In this way, the vehicle’s driving stability and agility are
increased in equal measure. Depending on the driving situation, the
fully variable electric BMW xDrive system can implement any form of
power transmission: traction-optimised all-wheel drive with variable
torque distribution as well as pure front or rear-wheel drive.
Precisely controlled energy recovery optimises driving stability and efficiency.
In coasting and braking phases, both engines can feed energy back
into the high-voltage battery by means of a generator function. This
makes a significantly higher recuperation performance possible than
just one motor. The fully electric BMW xDrive system also makes it
possible to control these energy recovery processes in such a way as
to ensure maximum driving stability and efficiency at all times. The
system is designed so that the more powerful engine on the rear axle
also takes on the main role in recovering energy. In curves and in
adverse road conditions, on the other hand, a higher proportion of
energy recovery performance is provided by the front engine.
Just like the drive torque, the energy recovery torque can also be
divided quickly and precisely between the two engines. In addition,
the intelligently networked drive torque control system ensures that a
stable driving condition is also guaranteed during deceleration
processes. The slip control set by DSC helps to prevent unstable
driving conditions caused by excessive braking recovery. The
transition from deceleration through recovery to the intervention of
the hydraulic braking system is not perceptible to the driver. The
integrated braking system also contributes to this, providing a
constant pedal feel at all times.
The figures for fuel consumption, CO2 emissions, power
consumption and range are measured using the methods required
according to Regulation (EC) 2007/715 as amended. These figures refer
to vehicles on the automotive market in Germany. For span widths, the
specifications take into account the effects of any optional equipment.
All values were calculated based on the new WLTP test cycle. WLTP
values are taken as the basis for determining vehicle-related taxes or
other duties based (at least inter alia) on CO2 emissions
as well as eligibility for any applicable vehicle-specific subsidies.
Further information on the WLTP and NEDC measurement procedures can
also be found at www.bmw.de/wltp.
More information about the official fuel consumption figures and the
official specific CO2 emissions of new passenger cars can
be obtained from the “Guideline on fuel consumption,
CO2 emissions and power consumption of new passenger
cars”, available free of charge from all outlets, from Deutschen
Automobil Treuhand GmbH (DAT), Hellmuth-Hirth-Str. 1, 73760
Ostfildern-Scharnhausen, and at https://www.dat.de/co2/.
Please address any queries to:
Corporate Communications and Policies
Bernhard Ederer, BMW Group Innovations and Design
Communications
Tel.: +49 (0) 176 601 28556, Email: Bernhard.Ederer@bmwgroup.com
Dieter Falkensteiner, BMW Group Innovations and Design Communications
Tel: +49 (0) 151 601 51813, Email: Dieter.Falkensteiner@bmwgroup.com
Almut. Stollberg, Head of Communication Innovation, Design, Technology
Tel: +49 (0) 151 601 96543, Email: Almut.Stollberg@bmwgroup.com
Internet: www.press.bmwgroup.com/deutschland
E-mail: presse@bmw.de
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Original Press Release