Integrated Starter Generator

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INTRODUCTION

INTRODUCTION

In the last decades the automotive industry has been investigating alternatives to conventional internal combustion engine powered vehicles in order to improve their fuel efficiency and to reduce their greenhouse gas emissions. In 2002 automotive manufacturers have announced plans to improve passenger vehicle fuel economy with 25% or more by year 2005. Fuel economy improvement levels beyond current mandates are likely to be legislated during the next five years in North America. In Europe and Asia the mandates for reduced CO2 emissions are already coming into effect.

This challenge of fuel economy standards is promoting optimised and sometimes novel vehicle powertrain architectures that combine the traditional internal combustion engine (ICE) with various forms of electric drives. The different types of the hybrid electric vehicles (HEV) are real competitors of the classical ICE driven cars. Today hybridised power trains are already commercially available. In such type of cars hybrid spin-off applications, such as the integrated starter-generator (ISG) are emerging with benefits to hybrid electric vehicles, but with little or no cost/performance penalties. The ISG replaces the conventional starter motor and the alternator (generator). It provides, beside its two basic functions (starter and alternator), an auxiliary one, as a convenient automatic vehicle start-stop system for further improved fuel efficiency. The electronic control system switches off the ICE at zero load (such as when standing at a traffic light) and automatically restarts it using the ISG very rapidly when the gas pedal is pressed. The IEC is accelerated to the required cranking speed (idle speed) and only then the combustion process for instant ignition is initiated. During braking the ISG can convert the vehicle’s kinetic energy into electrical energy, and then feed this power back into the electrical system. As it fully supports the stop-and-start operation, electric drive-off and acceleration and recycling of braking energy the ISG helps to reduce both fuel consumption and emissions.

This paper presents different constructing variants, the advantages and benefits of the ISG. A part of the report deals with the comparison of different electrical machine types that could be used for ISG applications, mentioning also some typical commercial available units. In the final part of the report a switched reluctance machine (SRM) for ISG application will be presented, which was designed, built up and tested at RTWH Aachen (Germany).

HISTORY

HISTORY

In 1900, while employed at Lohner Coach Factory, developed the Mixte, a 4WD series hybrid version of “System Lohner-Porcshe” electric carriage previously appeared in 1900 Paris World Fair. The Mixte included a pair of generators driven by 2.5-HP Daimler IC engines to extend operating range and it could travel nearly 65 km on battery alone. The Mixte broke several Austrian speed records, and also won the Exelberg Rally in 1901 with Porcshe himself driving. The Mixte used gasoline engine powering a generator, which in turn powered electric hub motors with a small battery pack for reliability. It had a top speed of 50 km/hr and a power of 5.22 kW during 20 minutes. George Fischer sold hybrid buses to England in 1901; Knight Neftal produced a racing hybrid in 1902. In 1905, Henri Pieper of Germany introduced a hybrid vehicle with an electric motor/generator, batteries and a small gasoline engine. It used the electric motor to charge its batteries at cruise speed and used both motors to accelerate or climb a hill. The Pieper factory was taken over by Imperia, after Pieper died. The 1915 Dual Power, made by the Woods Motor Vehicle electric car maker, had a four-cylinder ICE and an electric motor. Below 15 mph(24 km/hr) the electric motor alone drove the vehicle, drawing power from a battery pack, and above this speed the “main” engine cut in to take the car up to its 35...
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