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Siemens' Electric Powerplant for Hybrids Brings Vehicles of Tomorrow A Step Closer to Reality

10 December 1997

Siemens' Electric Powerplant for Hybrids Brings Vehicles of Tomorrow A Step Closer to Reality

                   Power Unit is Industry's Most Efficient

    Auburn Hills, Mich., Dec. 10 -- Siemens Automotive has
developed a maintenance-free electric power unit for hybrid electric vehicle
(HEV) applications.
    The technology -- under development by Siemens engineers in Wurzburg,
Germany -- is being refined for use on Audi's "duo" hybrid vehicle.
    "We think the vehicles of tomorrow could very well incorporate a hybrid
configuration -- and we're developing technologies accordingly," said George
Perry, president and CEO of Siemens Automotive.
    "The electric powerplant we are now working on could be one of the
enablers that brings into reality an 80 mile-per-gallon vehicle that produces
only trace emissions."
    Perry said the Siemens electric power unit is the most efficient for HEVs
to date.
    At approximately 44 pounds, the 21-kW powerplant is capable of producing
29 horsepower -- the best power/weight ratio in the industry.  Efficiency
performance of 93-percent also sets benchmarks for HEV electric powerplants.
    HEVs like the Audi duo combine a combustion engine and an electric drive
system that can draw power from an energy storage device like an advanced
battery.
    Energy from fuel powers the heat engine, and power to drive the wheels
comes from two sources -- the primary engine via the transmission and/or
energy from the electric motor and energy storage device.
    Energy for storage by the batteries is provided through two sources -- the
primary heat engine itself, and the use of regenerative braking.  Energy that
is traditionally lost as heat when a vehicle slows down is recaptured using
this technology.
    "As a result of this hybrid configuration, HEVs can offer a number of
advantages," Perry explained.  "Unlike purely electric vehicles, their range
is not dependent solely on batteries -- and emissions can be reduced because
smaller heat engines -- often a diesel -- may be used."
    The electric power unit under development by Siemens comprises:

    * A water-cooled, permanent-magnet AC electric motor that's capable of
developing more than 130 foot-pounds of torque.  Under overload conditions,
the unit can deliver as much as 35 kW (48 horsepower) for limited periods.
The motor is less than 11 inches in length -- or roughly the size of a
traditional lighting alternator;
    * An AC/DC converter with drive- and vehicle-software.  The converter
turns the DC input into a 3-phase AC frequency required for the motor.  The
software ensures smooth "change-over" to heat engine power "on the fly"; and,
    * A DC/DC converter and charger.  This converter turns the 264 V supply
from the batteries into a 12 V DC for use on the vehicle's electrical system.
Using the onboard charging unit, a HEV battery (or battery pack) can be
recharged in five to seven hours from any household electrical outlet.
    From a standstill, the Audi duo reaches 5O km/h with the Siemens electric
power unit in only 9.5 seconds.  The duo achieves a maximum speed of 100 km/h
using the power unit as its only energy source.  For more information and
artwork please see the Siemens Automotive web site at: http://www.siemensauto.com.

SOURCE  Siemens Automotive