Risparmiare Energia

BMW Introduces Intelligent Alternator Control with Regenerative Braking; Reduces Fuel Consumption by About 4%
29 September 2006

At the Paris Auto Show, BMW introduced a system it calls Intelligent Alternator Control (IAC) to generate electric power for a car’s on-board network exclusively in overrun and during braking—IAC thus also incorporates a system for regenerating brake energy.

The system is part of a larger BMW initiative to improve the overall efficiency of a vehicle by decreasing ancillary loads on the engine and recuperating more of the waste heat energy. (BMW is currently involved in one of several projects tackling the development of a thermoelectric waste heat recovery system targeted to deliver a 10% improvement in fuel economy. More on this below.)
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A mid-size car currently has an electric power requirement of about 3.5kW for all its systems. (See chart at right.) Hence, the generation of electricity for the car’s on-board network consumes an increasing share of the power generated by the engine.

With the IAC system, the alternator will operate primarily when the engine has no need for power—i.e., in overrun or during braking. The alternator remains passive while the car is under power, with needed electrical power provided by the battery.
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The battery is charged to only about 80% of its capacity whenever the engine is pulling the vehicle, always maintaining an adequate reserve for the consumption of energy at a standstill and for starting the vehicle.
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La Brake Energy Regeneration.

Togliere il piede dall’acceleratore finora significava lasciare dell’energia inutilizzata. Brake energy regeneration cambia la situazione: il generatore trasforma l’energia cinetica dell’albero motore che si libera durante la frenata in energia elettrica. La batteria viene quindi, per così dire, ricaricata “gratuitamente”. Durante il viaggio la batteria deve quindi ricaricarsi meno, alleggerendo così il motore e riducendo il consumo di carburante.