The total power drawn by electric loads on top-class vehicles today is settled around 2 kW, but it will soon overcome, the threshold of 5 kW with the scheduled massive introduction of active suspension and drive-by-wire systems, as well as of several electric and electromechanical devices devoted to engine control and drive safety. Any action aimed to reduce fuel consumption and pollution emission on next-generation vehicles will require more electric power. Specifically, noticeable reductions of fuel consumption and pollution will be obtained by electrification of auxiliary mechanical drives that today are directly or indirectly powered by the engine shaft. Electrification will increase the efficiency of such systems that, when disconnected from the engine shaft can be more rationally housed in the vehicle but not necessarily placed close to the engine. In addition, their operation can be made independent from the engine speed, achieving a greater flexibility. Some pioneering high-efficiency vehicles that have recently been introduced into the market feature a small electric propulsion system connected in "parallel to the conventional internal combustion engine according to the so-called mild hybrid vehicle approach. Such an auxiliary propulsion system acts as an integrated starter generator (ISG) and supports or replaces the internal combustion engine in low efficiency operational conditions (stop-and-go driving, accelerations, light loads, load peaks, etc.) while allowing regenerative braking 1-5.
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