Tesla drag power analysis

Discussion in 'Tesla' started by bwilson4web, Jul 27, 2018.

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  1. bwilson4web

    bwilson4web Well-Known Member Subscriber

    I was happy to discover the EPA includes entries for EVs in the "Test Car Database" including the roll-down coefficients. This means we can plot the rolling drag power metrics as a function of mph. Using 500 W as the overhead electric load, here are the plots:

    Each Y-axis value is equivalent of 5 hp.

    These are parametric, loss-less, drag power curves at the wheel-to-road interface. I need the kW consumption at 30 mph and 60-75 mph for each model Tesla to correct the fixed overhead and efficiency loss of these curves. Normally we use benchmarks at two, different speeds to adjust for losses:
    • tire flex losses
      • there can be shock absorber losses on poor roads
    • wheel bearing and CVT joint losses
    • differential gear losses
    • reduction gear losses from motor to differential
    • motor losses (better for PM versus cheaper induction)
    • inverter losses (better for silicon carbide versus silicon)
    • typical metrics are at the input to the inverter electronics
    Bob Wilson
    Last edited: Jul 27, 2018
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