Magnetics Business & Technology - September/October 2023 - 17

FEATURE ARTICLE
phase design with a dual inverter. This forms the basis for a very
substantial increase in peak output that remains on tap up to high
speeds. The motor's power density of 2.41 kW/kg represents an
increase of 25.5% over the unit that drives the rear axle of the
BMW i7 xDrive60 and means that the BMW i7 M70 xDrive is fitted
with what is currently the company's most powerful electric motor.
This new standard-setting figure can be attributed to a BMW
Group-patented innovation developed under the umbrella of BMW
EfficientDynamics, which uses six excitation windings in the motor's
stator instead of the customary three. The resulting " double
excitation " compared with conventional units allows the electric
motor to generate an extremely high output, despite its exceptionally
light and compact design, and to maintain it continuously into
the higher echelons of the speed range. This solution is also far
superior to a drive configuration using two motors at the rear axle
in terms of both power density and efficiency.
The first series-produced vehicles of the new BMW 7 Series have
already rolled off the production lines of BMW Group Plant Dingolfing.
According to Milan Nedeljković, BMW AG Board Member for Production,
" Our new BMW 7 Series is the first luxury sedan in the world to
offer customers a choice between three types of drive. Whether fully
electric, combustion-powered or, soon, plug-in hybrid, we have the
flexible production structures and outstanding integration skills we
need to manufacture such a diverse range of drives efficiently. "
i7 M70 xDrive's rear-axle motor, in particular, to achieve unprecedented
levels of power density. The drive unit has a sixThe
motor powering the rear axle generates peak output of 360
kW/489 hp. Its precisely coordinated interaction with the 190
kW/258 hp motor at the front axle creates an electric all-wheeldrive
set-up generating system torque of 1,015 Nm (748 lb-ft) in
Sport mode and as much as 1,100 Nm (811 lb-ft) when M Launch
Control or the M Sport Boost function is activated, also offering
outstanding pulling power.
With the M Launch Control function, both drive and traction control
are integrated into the engine control unit. This ensures the power
generated by the electric motors is metered extremely precisely,
allowing the drive system's M-typical performance characteristics
to be instantly converted into stunning acceleration without any
loss of traction. For more info, see www.bmw.com.
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September/October 2023 * Magnetics Business & Technology 17
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Magnetics Business & Technology - September/October 2023

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