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Re: (ET) Alltrax output!
On 23 Oct 2006 at 21:44, Ralph & Elaine Vogan wrote:
> The Alltrex does do field weakening (in forward only).
I was sure I recalled that it didn't. So I went back through all my old
emails from Steve Richardson. In one of our exchanges, I reacted to
something he'd said about the field map by saying that it didn't sound
like
the Alltrax did FW. Steve didn't counter that remark. But in fact at
that
point it was quite early in the development cycle and he didn't really
know.
My apologies. It turns out that I was wrong, and the Alltrax WILL perform
FW to increase top speed. However, as one person pointed out, the user
has
to explicitly turn that feature on; apparently, it's off by default.
I haven't done this on my Alltrax, and my E15's top speed is definitely a
bit slower than it was with the old GE control (which seldom bothers me).
In fact, I'd entirely forgotten about the "Turbo" button in the control
software.
FYI, here's some of what Steve wrote about how the Alltrax controls the
E15
field :
= = = = =
Fri, 27 Jun 2003
The Alltrax controller automatically adjusts the field strength to keep it
within a percentage of the armature current. The armature current and the
field current is monitored by the microprocessor and it decides, based on
programmable variables, what the percentage should be.
= = = = =
Sat, 28 Jun 2003
As I understand the "Theory discussion" I had with Damon the controller
will
weaken the field with a light load and pedal-to-the-metal. If the load
increases then the controller will increase the field current to
compensate.
This is really more to protect the armature than to control speed. If
the
field is too weak with a given load then the armature current may rise to
high.
= = = = =
Wed, 7 Apr 2004
The Alltrax controller maintains a relationship between the field current
and
the armature current that is in the motor's "sweet spot". But we have
implemented a "Turbo" mode that can be turned on/off by the user. It
lowers
the field strength a little below normal when the throttle is full on and
the
controller is not in current limit ( has a light load).
= = = = =
Hope this clears things up.
David Roden - Akron, Ohio, USA
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