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Ksterr

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I've been a long time lurker on this forum and finally just made an account.

My final year project is in the design of a regenerative braking system for a EV. I'm reading a Modern electric vehicle design Book and came across an equation that I don't quite understand.

This equation finds power at the drive wheels:

Pd = V/1000 (Mgfr + 1/2*ρa*CD*A*V2 +M*δ*dV/dt) (kW),

The book says to integrate this equation w.r.t driving time over a given driving cycle. This will than yield energy in traction and energy in braking.

What I don't get is, aren't all these constants except for dV/dt

M = mass

g = 9.81

fr = tire rolling resistance

ρa = air density

Cd = coeffificent of drag

A = frontal area

v = speed

δ = rotational inertia factor