Seth Murray wrote:
>
> Peter VanDerWal wrote:
>
> > the resistance through the brushes on a moving comutator is different
> > than on a stationary one
>
> I have been wondering about this. Lets say I am driving in second
> gear. When I first start my EV moving, the motor wants lots of amps.
> Once it gets up to 4,000 rpms or so, the motor seems to have a limit on
> its current draw, even if I put my foot on the floor (current well
> under the current my batteries and controller can deliver). As soon as
> I shift into 3rd, though, the motor will take all the current my poor
> batteries and controller dish out. The only thing I could thing of was
> that the resistance through the motor must change depending on rpms,
> which because of Ohm's law would allow the motor greater current at
> lower speeds. I know there are other factors involved, but do I have
> any clue of what's going on? =)
>
> Seth
>
> --
> QUESTION INTERNAL COMBUSTION
>
> My electric truck page, with lots of photos and a 25 page conversion
> journal. Check it out!
> http://www.wpi.edu/~sethm (NO MORE POPUPS!!)
>
> My EV Album page
> http://www.austinev.org/evalbum/387.html
HOooooH ha ha HHHHEEEE! Yea rather obvious is the BACK EMF of the motor.
As it spins up it becomes a generator, you need to over come this with
more volts or your motor will spin up to a certain speed and then wind
out no futrther!!!!
Basic V/F ratio. volts to Frequency or RPM same thing.
All motors have rpm and torque curves. You are just seeing them .
Us racers swear at them and try to manipulate them to our best uses.
Check the motor curves from Advanced DC and from Rod at EVparts, and Ken
Koch at KTA.
--
Rich Rudman
Manzanita Micro
www.manzanitamicro.com
1-360-297-7383,Cell 1-360-620-6266
