Re: Shunt field motors

["Mander, Art" <amander@tristategt.org>]

My February 26th post about shunt field motors and Interpoles brought out
some good responses (as I hoped it would).

Kevin Zak of WarP Series Motors, NetGain Technologies and also Paul Compton
pointed out that there is no room in an ADC or WarP 8 or 9 inch motor to add
interpoles  I looked through the Netgain web site at  http://www.go-ev.com/
and they are right - I stand corrected. (really informative site).  The only
disassembled motor I had seen is my 6.8" GE, which has plenty of room, and
my 9" Kostov, which has interpoles.  Lee Hart mentioned that his 6.7" ADC
has maybe ¾" space for interpoles.  That isn't enough.  As Tom Shay said,
there needs to be at least 2" and in the Kostov it's more like 3".

So if interpoles can't be added into the motors most popular with U.S. EV
conversions, could the brushes be adjusted to allow for regen?  Kevin, does
NetGain advance the brushes for improved performance?  The solution may be
an add-on adjustable brush advance mechanism, as suggested by Andre
Blanchard and Paul G. Neon.  Ideally the advance or retard would be
activated by the DSP or microcontroller in the motor controller.  It would
need to be strong enough to overcome the stiffness of the wiring to the
brush holders and work in a dusty and hot environment.  And the system may
still need one extra brush, small and narrow, for sensing 

Regenerative braking is a worthy goal with at least three benefits:

*	Improved safety (coasting is not good)
*	Increased range (though often debated - Victor have you been able to
quantify this with the AC drive regen engaged and disabled?)
*	Increased battery capacity (according to Nawaz Qureshi at US
Battery, who once said "Blasting AGM's with 2C to 3C rate at the start of
the charge, if you can do it, just for a few seconds, tends to break up the
grid-active material barrier layer in the positive plates resulting in the
prevention of loss of capacity owing to this layer that is peculiar to the
AGM's if you deep cycle them").
   
Art Mander, Denver