VS - Electrical Systems From Stop-Start to Hybridization

Electrical energy Electrical energy is about supplying a certain electrical power level for a time duration, the unit is the Wh (watt-hour) or the Joule (watt-second). ●● Alternators convert fuel to electrical energy via the combustion engine crankshaft rotation. ●● Batteries are able to store energy; they are specified among others by their energy capability in Wh defining their ability to supply a continuous power for a certain time after a storage phase.

Converts kinetic energy to electrical energy Similarity to a bike that is able to generate green energy in a coasting phase via its dynamo, vehicles charging systems are able to convert kinetic energy to electrical energy, either in early coasting phases or better in braking phases.

Conversion from kinetic to electrical energy

E = 1 x M x V 2 2

E = W x t

Deceleration

Energy recovery slope

Energy flowback to the drive train

Energy flowback to the engine belt drive

Energy conversion to electricity

Energy storage in batteries

Regenerative braking In deceleration phases, the vehicle braking system converts a portion of kinetic energy to heat in the brake discs and drums through a friction process, this conversion leads to pure energy losses and inevitably to wear of braking components, but it is not the unique source for braking. Considering a certain braking demand, it can be split in multiple braking sources: ●● The engine natural braking, a load that relates to internal friction, engine pumping losses (pistons)

●● Load on the engine via belt and chain drives (auxiliary and distribution drives)  Torque demand for the timing components  Torque demand for oil pump  Torque demand for water pump  Torque demand for A/C compressor  Torque demand for energy conversion by the alternator

l Other losses relating to aerodynamics and miscellaneous rolling frictions ( tyres etc..).

and drivetrain efficiency ●● The conventional brakes

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