Siemens to Begin Production of First 42-Volt Starter-Generator System by Spring of 2001
6 March 2000
Siemens to Begin Production of First 42-Volt Starter-Generator System by Spring of 2001
DETROIT, March 6 In approximately one year, Siemens
Automotive will begin the supply a new vehicle supplemental power plant called
a starter-generator, which will be offered as standard equipment on vehicles
in Europe.
The introduction of the starter-generator also will bring about the
transition from a 14 to a 42-volt vehicle electrical system, a development
that has been generating enormous interest in the automotive industry as the
average content of vehicle electrical/electronic components and systems
continues to escalate.
"With the advent of starter-generator and a supporting 42-volt vehicle
architecture, power struggles will soon become a thing of the past," said Ted
Vartabedian, system engineer for Electronic/Electrical Distribution Systems,
Siemens Automotive.
"The increasing demand for electrical power during low engine speed or
cold starting will no longer overburden a vehicle's power supply with starter-
generator," said Vartabedian.
An increasing number of energy consuming technologies, such as electrical
power assisted steering and electromechanical valve train, for example,
require generator outputs from 4 to 8 kilowatts across the entire engine speed
range -- more power than conventional generators can provide. A solution
emerging in this new millennium is an innovative system with an integrated
induction machine that generates and distributes energy under the hood.
The starter-generator, developed by Siemens Automotive, reaches a peak
generator output of 8 kW with an efficiency of more than 80 percent across the
entire speed range. For comparison: a conventional generator puts out 1.5 kW
with a maximum efficiency of 70 percent, which drops to a meager 30 percent at
high speeds.
With starter-generator, the engineers at Siemens intend to replace the
starter, the generator and the flywheel. This technology is linked to a
number of beneficial applications, for example, an automatic start-stop system
or pulse start. This results in synergy effects -- the use of electric energy
can be optimized resulting in reduced fuel consumption and emissions.
Due to its extremely compact dimensions, the starter-generator can be
placed directly on the crankshaft between the engine and the transmission.
High electric power output, even at low speeds enhances the performance of
comfort and convenience features, such as the air conditioner, seat heater or
rear-window defroster. Perhaps, the most noteworthy feature of the starter-
generator is its inherent wear-free, maintenance-free design, due to the
contactless transmission of power.
The Siemens starter-generator provides an auxiliary function as a
convenient automatic vehicle start-stop system for further fuel efficiency
gains. Once more, in this mode of operation the components of the starter-
generator are not subject to any wear because of the system's brushless
design. This system switches off the combustion engine at zero load -- at
traffic lights, for example -- and automatically restarts it in less than one
hundred milliseconds the next time the gas pedal is pressed. The pulse-start
technology accelerates the combustion engine to the required cranking speed
(idle speed) and only then initiates the combustion process, another feature
that helps reduce both fuel consumption and emissions.
The starter-generator is just as versatile when it comes to other
disciplines. In the boost mode, the starter briefly serves as a second engine
to drive the vehicle or provide acceleration in the low-speed range. This
provides a short-term power boost of 15kW, depending on the configuration of
the starter-generator and battery. In the "retarder" mode, the starter-
generator demonstrates yet another strength in its ability to convert kinetic
energy to storable electric energy.
Driveability is improved significantly by the torsional-vibration damping
provided by the starter-generator. Without active damping, load reversals
and/or abrupt acceleration could cause low-frequency vibration in the
powertrain that, in turn, might cause vehicle jolting.
In parallel with starter-generator development, Siemens Automotive is
developing a production-ready 42-volt vehicle electric system in order to
supply the energy required by starter-generator and other power-hungry
functions in the car of the future. For example, the electromechanical valve
train (EVT) and the electrically controlled air-conditioning system will have
power requirements of about 3 kW each. Brake-by-wire and electrical steering
systems also will add to the demand for a more powerful electric system.
Siemens Automotive plans to introduce the new, more powerful electrical
system in progressive stages over the next five years. Vehicles with dual
electric systems are conceivable during a transitional phase; which might
promote the use of new features for increased safety and comfort in vehicles.