# Re: [EVDL] Controlling a SepEx motor



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

You can download the Curtis Sepex manual from their web page. The manual explains how to tune the controller. If anything, you want to err on the side of a stronger field. Too weak a field can lead to major arcing and damage.




________________________________
From: AMPhibian <[email protected]>
To: [email protected]
Sent: Thursday, May 28, 2009 7:19:13 PM
Subject: [EVDL] Controlling a SepEx motor


I'm trying to help a friend find a controller for an 11 inch GE Sepex motor.
http://toddperkinsdesign.com/images/inhaler/forums/ge%2001.jpg GE motor 
http://toddperkinsdesign.com/images/inhaler/forums/ge%2002.jpg GE motor2 
http://toddperkinsdesign.com/images/inhaler/forums/ge03.jpg GE motor3 
He's trying to find a 48 volt setup for now, and I thought he could use an
Alltrax DCX, but apparently they are setup for specific motors: 
"I am sorry to say that the DCX line of controller are built to a known
motors. Each motor has a unique field map or the controller will overheat
the motor or burn itself out from sourcing too much current. If you can find
a graph for your motor I might be able to match it to an Alltrax existing
map."
Anyone have a field map, or other ideas? Trying to keep this on the cheap,
but that may not be possible. Kelly, Curtis, Sevcon?

John
-- 
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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

You can also run a fixed voltage to the field, and use a series motor
controller on the armature. This reduces alot of the benefits of a SepEx
motor (regen, wider speed range), but does work -- there's a few cars on the
EV album using aircraft generators (similar to SepEx motors) with a fixed 24
or 36 volts to the field.

Z

On Thu, May 28, 2009 at 11:18 PM, David Dymaxion


> <[email protected]>wrote:
> 
> > You can download the Curtis Sepex manual from their web page. The manual
> > explains how to tune the controller. If anything, you want to err on the
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

I realize that Curtis and others are able to be programmed but was hoping to
find a field map for that motor so he might be able to use a less expensive
Alltrax DCX controller. It seems like a long shot but I thought I'd check. 
I guess the only Sepex options are Curtis, Kelly and Sevcon, and max out at
84-120 volts?
John




> David Dymaxion wrote:
> >
> > You can download the Curtis Sepex manual from their web page. The manual
> > explains how to tune the controller. If anything, you want to err on the
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

Interesting, is there some ratio to use in selecting the field voltage, as in
some percentage of the main voltage?
John



> Zeke Yewdall wrote:
> >
> > You can also run a fixed voltage to the field, and use a series motor
> > controller on the armature. This reduces alot of the benefits of a SepEx
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

I'm not sure. I think it was trial and error. If you have too high, it
will be low rpm, and high torque, but might overheat the field. If you have
too low, it will be high rpm, but have little torque. Some, like the big
13" GE SepEx that I have are designed for the field voltage to be as high as
the armature voltage -- both are rated at 96 volts. However, I think that
alot of them are designed for the field voltage being a bit lower than the
armature voltage. I never found a countroller for mine.... 

Z



> AMPhibian <[email protected]> wrote:
> 
> >
> > Interesting, is there some ratio to use in selecting the field voltage, as
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

My Military Starter/Generator uses the same voltage as the armature 
but the field is limited to 20 amps. So far the motor works good. The 
military Starter/Generator style motors are unique in that one of the 
field windings is common with the armature. So only three usable 
external connections for power. One connection is for monitoring 
voltage output.

Pete

Yes, the higher the amps in the field the slower it will go overall 
but the higher the torque.





> Zeke Yewdall wrote:
> 
> > I'm not sure. I think it was trial and error. If you have too
> > high, it
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*



> Jeff Major wrote:
> > I don't know what the field was designed for in this motor. I had a
> > smaller (6.6 inch) GE SepEx motor which I did not have any data on
> > and wanted to use it with a Curtis SepEx controller. It took some
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

So we can try running it with a series controller on the armature and a
rheostat on the field to adjust it. What sort of current does the field
draw, and what type of rheostat can deliver what is needed?

John




> Lee Hart wrote:
> >
> >
> > Remember that the "controller" for a shunt/sepex motor is pretty simple.
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*



> AMPhibian wrote:
> > So we can try running it with a series controller on the armature and a
> > rheostat on the field to adjust it. What sort of current does the field
> > draw, and what type of rheostat can deliver what is needed?
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

Great stuff! Thanks.

John




> Lee Hart wrote:
> >
> > AMPhibian wrote:
> >> So we can try running it with a series controller on the armature and a
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*

Wait, if in this example we have a field measurement of 5 ohms, why did you
use 10 ohms in the calculation?

John



> Lee Hart wrote:
> >
> >
> > For example, suppose the field measures 5 ohms.
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Controlling a SepEx motor*



> AMPhibian wrote:
> > Great stuff! Thanks.
> 
> Except for a typo...
> ...


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