Re: EVLN(1-O-X revolutionary digital EV motor)

["Peter VanDerWal" <peterv@peoplepc.com>]

> And, it stands to reason that this effect would be most
> obvious in modes of operation that force the motor to
> operate over the widest range of operating points.  Such
> as urban stop and go traffic.  Efficiency must therefore
> range from 0 at 0 RPM to something no greater than the

Actually you could also say that efficiency is at infinitee at zero rpm.
Efficiency is power out divided by power in.  0/0 is technically zero but
the result of any number divided by zero can also be said to be infinite.

It's a moot point.  The only time the motor is running at such low
efficiency is when it's drawing very little power.  On a full size EV using
100 watts instead of 150 watts at 2 mph isn't going to have much effect on
your range.

> peak efficiency of the motor, and so the average could
> believably be much lower than more steady-state operation
> over a narrower speed (and load?) range that lies in a
> more favourable region of the efficiency map.

Ignoring the fact that there is at least three different ways to figure
"Average" (Mean, mode, & median)...
If you are concerned about range (that's the real point right?)  you have to
consider how much power is spent at each unit of time (pick small units)
add it all up and you'll find that getting better efficiency at super low
power levels (relatively speaking) isn't going to amount to a hill of beans.

It's the over-all power that matters, i.e. can we go further on less power.



> Also, one should expect an EV with a fixed drivetrain
> ratio to exhibit a greater difference between steady-
> state operation and urban traffic conditions than would
> an identical vehicle with a multi-speed transmission.
>

Why?  Realistically it all depends on the torque map of the motor.  Many AC
motor/controllers have nearly flat efficiency over a wide range of
torque/rpm, for these motors a multi-speed transmission might actually
decrease efficiency (due to their higher friction).

> It will be interesting to see if the 1-O-X folks come up
> with anything of practical application as there may
> certainly be some gains realisable, especially given the
> OEM preference for the simplicity of a single ratio
> drivetrain.

It would be interesting, but given the fact that the best thing they have to
brag about so far is an obscure plug-n-play Mr. Microphone, I'm not holding
my breath.