Basics of Electric vehicle design

[omnitech]

Just some notes based on 4 electric reverse trike builds:

Series-wound motors are very current hungry in the upper half of their rpm's.

Try to keep your motor as cool as possible. More  current draw equates to more heat. As motor temperature rises above 70 degrees fahrenheit, it takes more and more current to develop the same amount of power (look up "peak cool horsepower"). The additional required current and the heat soaking of the electrical and electronic drive systems reduces  component service life AND range.

Even with the parasitic losses of a transmission, they pale in comparison to the range limitations, the loss of peak cool horsepower and the current penalty of single-speed drives.

Don't take my word for it, do your own research. It's all about efficiency.  If you can get the same performance with greater range from the same amount of stored energy, why not?
 
Let's start a dialogue!


Nick















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[worldpax]

How about the AC induction motors? I was planning an HPEVS AC-35 at 72 volt and 550 amps. That is until the wife saw the price and now I get to use a bike engine.

[captainamerica]

Not to be "that guy" but can we put this in the "Tech" page, it seems like it would be more at home there.

-Andrew

[omnitech]

AC motors are a good alternative to series-wound DC motors, if you can get past the price.  I prefer the latter, because when they are coupled with a well designed controller (Synkromotive, Zilla) it becomes a potent package at a decent cost.  The trick is to manage current draw across the lower 50% of the rpm range, and keep motor rpm below 3500. A transmission accomplishes this quite nicely at reasonable cost.