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-   -   best motor type (https://www.bikeforums.net/electric-bikes/861461-best-motor-type.html)

Kevin Harvey 12-07-12 11:55 AM

best motor type
 
I was reading a web site about Electric car motor convertions (which i'd like to do one day) & on this site they said that Dc motors were nowhere near as efficient as AC as the torque was greater all the way up the revs , the controller they call an inverter & they charge the battery etc. I had a 500 w not geared hub motor & am sure it was AC as the electric wire to motor were single copper & small for 500w.It was the one that was no good for the hills to which i then went to cyclone.
Which is DC ----seems they have different conclusions to me I wonder what the TESLA motor is.--does any one know?

FMB42 12-07-12 06:09 PM

As far as I know, all common electric bicycle conversion hubmotors are of the DC type. Nearly all of these are BLDC or "Brush-Less DC (older brushed DC hubmotors are pretty much obsolescent these days).

Unless I'm mistaken, all automotive hybrids are also driven by BLDC motors (including "plug in" vehicles).


The Tesla Roadster, the General Motors EV-1, and AC Propulsion's Tzero, etc, (as "pure electric vehicles") use 3-phase AC Induction motors (in part, for the reasons listed by the website you mention).


The lack of "hill climbing" power that you experienced with your previous e-bike power system could have been due to other reasons (including a lack of gears).

graywolf 12-08-12 01:13 PM

Actually, most of the brushless motors are AC. The controller consists of an inverter and a phase converter. The inverter changes the DC from the battery to AC, then the phase converter converts it (usually) to 3-phase. The throttle control changes the frequency to control the speed. Why do you think the wires from the controller to the motor are called phase wires?

Since the controller takes the same type input as a DC motor the brushless motor looks like a DC motor from that viewpoint.

In fact DC motors produce infinite (mathematical definition of infinite) torque at zero rpm. That means real DC motors move off at start up much more smoothly than the AC ones and need no controller other than a reostat. The AC motors (brushless) however are typically smaller and lighter.

There are always tradeoffs, in engineering you chose the ones that work best for your specific application.

Kevin Harvey 12-10-12 11:57 AM

I did know that a brushless motor was 3 phase but with what i had seen up until now was that it was 3phase but still DC(which has always had me puzzeled) -as DC for brushless motors is not stated-& as that hub motor from china (E Bay) the copper wires to motor were one single thick wire & it did state somewhere that it used AC -- thanks you two guys for for your info -

cerewa 12-10-12 08:20 PM


Originally Posted by Kevin Harvey (Post 15034846)
I did know that a brushless motor was 3 phase but with what i had seen up until now was that it was 3phase but still DC(which has always had me puzzeled) -as DC for brushless motors is not stated-& as that hub motor from china (E Bay) the copper wires to motor were one single thick wire & it did state somewhere that it used AC -- thanks you two guys for for your info -

When people say "Alternating Current" they usually mean current that alternates at a specific frequency such as 60Hz. The current received by a "brushless DC" ebike motor is essentially alternating current but it doesn't have a specific frequency, and the power output from the battery is DC (so it makes sense to call it a brushless DC motor) even though the electronic controller puts out "AC" power.

powell 12-11-12 03:55 PM

Not just three phase
All number of phases
3 phase on Eplus
7 phase on Tidal Force
5 phase on FALCO
Just examples

Kevin Harvey 12-17-12 03:42 AM

Thank you we never stop learning--sure is a lot for me with electrics. i just had a Battery pack up need to start another thread as different suject.


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