Siemens Automotive’s Integrated Starter Generator (ISG) technology is poised to play a leading role in helping Sport Utility Vehicle (SUV) makers reach their stated fuel economy improvement goals of up to 25 percent by 2005.”In real-world driving conditions, Siemens ISG-equipped test vehicles have demonstrated significant fuel economy gains,” said Kregg Wiggins, Siemens Automotive vice president of Powertrain, North America.
“Siemens’ ISG represents a substantial step toward realizing our customers’ fuel economy gains with technology that soon will be introduced into the market place.”The first of its kind to reach production, the Siemens ISG system will be a supplemental power plant application on a European small car platform, beginning in the next model year. Siemens’ ISG is on display this week in the company’s exhibit (booth #437) during the Convergence 2000 Conference on automotive electronics.
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The Siemens ISG replaces the conventional starter, generator and flywheel of the engine and provides an auxiliary function as a convenient automatic vehicle start-stop system for further improved fuel efficiency. The system switches off the combustion engine at zero load — such as when standing at a traffic light — and automatically restarts it in less than one hundred milliseconds when 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 for instant ignition, a feature that helps reduce both fuel consumption and emissions. ISG also optimizes the use of electric energy, further reducing fuel consumption and emissions.The components of the ISG system are not subject to wear and tear and are maintenance-free because of the system’s brushless stator and rotor design.ISG’s extremely compact dimensions allow it to 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.
These include the air conditioner, seat heater or rear- window defroster.ISG is just as versatile when it comes to other disciplines. In the boost mode, for example, 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 ISG and battery.
In the “retarder” mode, the ISG demonstrates yet another strength with its ability to convert kinetic energy to storable electric energy.Driveability is improved significantly by the torsional-vibration damping provided by the Siemens ISG. Without active damping, load reversals and/or abrupt acceleration could cause low-frequency vibration in the powertrain that, in turn, might cause the vehicle to jerk.
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By GlobalDataThe introduction of the Siemens ISG 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, driven largely by the increasing content of electronics solutions in vehicles.”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, Siemens Automotive system engineer for Electronic/Electrical Distribution Systems.
“The increasing demand for electrical power during low engine speed or cold starting will no longer overburden a vehicle’s power supply with ISG.”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.The Siemens ISG reaches a peak generator output of 8 kW with an efficiency of more than 80 percent across the entire speed range. In 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.
Siemens Automotive is a tier-one supplier of automotive and electrical- electronic systems and components with applications covering gasoline and diesel powertrain systems, safety and chassis systems, body electronics, electric motor drives and driver information systems. Worldwide sales in fiscal year 1998/1999 totaled $3.6 billion.
