[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: (ET) Controllers and inverters
A couple of things. Building pure sine inverters can be tricky, it's not the
sine wave generation that's the problem, you can do that very well with a
chip. It's getting that sine wave to drive, at high power, inductive loads
at high efficiency.
I'm sure the Alltrax is a wonderful controller and for those without the
ends and the ability to design those circuits it's a great way to go. With
that said, I don't expect their giving out the circuit any time soon,
they've encased it in epoxy. Manufacturers do this often to protect their
design. Think about it, the circuits from the ETs are 40 years old and
working without being encased, most car computers aren't encased either.
Encasing holds in heat too. I've built lots of circuits that work in harsh
environments without encasing them in epoxy. In fact I'm working on an
alternator circuit for my microhydro that won't be encased. Sure I'll make a
case (IP65) for it that will cost more than if I epoxy it but I have the
added advantage of being able to 'tweak' the circuit at a later date.
As for controllers blowing up. Back in the early 90's when a the 'new' SMPS
(switch mode power supply) were replacing clunky transformers in VCRs they
were popping like balloons at a carnival! We've learned a lto since then
about things like 'shoot thru' and the miller effect on high side 'N' type
MOSFETs so MOSFET break down isn't as big a problem as it once was. Now
bring in some of the new stuff from IR and others and you start getting
MOSFETS in the very low milliohms that can carry a lot of current. Check out
this honey, IRF3805PBF at 3.3mOhms and 220 amps!
Also when I design this controller I'm going to be very careful about the uC
algorithm. I'll ramp the controller up slowly and down slowly, I'll also
watch the shoot thru timing and I'll limit motor current electronically with
sensors.
I'm also going to measure, empirically, using a very accurate meter (HP
34410A 6-1/2 digital meter) using the 4 wire resistance method. This will
give me the exact resistance of the windings and I'll do it on more than one
motor.
Again thanks for all your inputs, they have been helpful.
Rob
-----Original Message-----
From: elec-trak-request cosmos phy tufts edu
Sent: Sunday, December 30, 2012 10:23 PM
To: elec-trak cosmos phy tufts edu
Subject: Elec-trak Digest, Vol 10, Issue 203
Send Elec-trak mailing list submissions to
elec-trak cosmos phy tufts edu
To subscribe or unsubscribe via the World Wide Web, visit
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak
or, via email, send a message with subject or body 'help' to
elec-trak-request cosmos phy tufts edu
You can reach the person managing the list at
elec-trak-owner cosmos phy tufts edu
When replying, please edit your Subject line so it is more specific
than "Re: Contents of Elec-trak digest..."
Today's Topics:
1. Re: Controller current capacity (was Elec-trak Digest, Vol
10, Issue 201) (harry landis)
2. Re: Controller current capacity (was Elec-trak Digest, Vol
10, Issue 201) (The CZ Unit)
3. Re: Controller current capacity (Robert Troll)
4. Re: Elec-trak Digest, Vol 10, Issue 201 (The CZ Unit)
5. Re: Elec-trak Digest, Vol 10, Issue 201 (RJ Kanary)
6. Re: motor ratings (Konstanty, Walter (GE Energy Management ))
----------------------------------------------------------------------
Message: 1
Date: Sun, 30 Dec 2012 19:38:54 +0000
From: harry landis <hlandis hotmail com>
To: elec-trak <elec-trak cosmos phy tufts edu>
Subject: Re: (ET) Controller current capacity (was Elec-trak Digest,
Vol 10, Issue 201)
Message-ID: <BLU173-W994C95F971CEA43837983BA3D0 phx gbl>
Content-Type: text/plain; charset="iso-8859-1"
Hi all,
Looks like it's already sold.
Harry Landis
From: hlandis hotmail com
To: elec-trak cosmos phy tufts edu
Date: Sun, 30 Dec 2012 18:28:11 +0000
Subject: Re: (ET) Controller current capacity (was Elec-trak Digest, Vol 10,
Issue 201)
All this talk of controllers reminds me that I have a 1204X-4407 controller
(data sheet and manual here:
http://curtisinstruments.com/?fuseaction=cProducts.dspProductCategory&catID=11
I connected it to 36V through a 250 ohm resistor and the B+ and B- came up
as advertised. I haven't done anything else. And I'm not likely to use it,
so the first $125 gets it, shipping in the US included. And I'll give it a 2
month warranty in case there is something wrong with it. I believe it came
out of a forklift that was scrapped.
Harry Landis
From: etpost drmm net
To: elec-trak cosmos phy tufts edu
Date: Sun, 30 Dec 2012 11:24:36 -0500
Subject: (ET) Controller current capacity (was Elec-trak Digest, Vol 10,
Issue 201)
On 30 Dec 2012 at 10:09, Robert wrote:
> What I will have to do is figure the maximum current just before the
> breaker pops and add 50% to this to make the circuit durable.
I'm no expert, but I'd say youi'll need at least that much and probably
more. IIRC, when Alltrax was designing the ET controller, they started
with
a 200 amp (peak) current limit and after some testing increased it to 300
amps.
FWIW, most folks who design controllers have large piles of silicon that's
given its life in the design process. It seems to involve a lot of loud
bangs and, now and then, smoke and flames.
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://cosmos.phy.tufts.edu/mhonarc/elec-trak/attachments/20121230/1f09bb8f/attachment.html>
------------------------------
Message: 2
Date: Sun, 30 Dec 2012 14:48:41 -0500
From: The CZ Unit <cz alembic crystel com>
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) Controller current capacity (was Elec-trak Digest,
Vol 10, Issue 201)
Message-ID: <50E09A99 70307 alembic crystel com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 12/30/2012 11:24 AM, David Roden (Akron OH USA) wrote:
I'm no expert, but I'd say youi'll need at least that much and probably
more. IIRC, when Alltrax was designing the ET controller, they started
with
a 200 amp (peak) current limit and after some testing increased it to 300
amps.
For the drive motor? Not quite sure if 200a will do it, but I have seen
well over 300 amps at the battery when blowing heavy snow, uphill, in
D1. Closer to 400 if I recall correctly. Granted the snowblower was
pulling a lot, but I was also forcing it into the chute with the E20's
drive motor. So 200a is not unbelievable.
FWIW, most folks who design controllers have large piles of silicon that's
given its life in the design process. It seems to involve a lot of loud
bangs and, now and then, smoke and flames.
These things do happen. :-) Fortunately I have the controller that
doesn't seem to be too concerned about the details of the motor. See, it
uses these things called contactors..... :-)
C
------------------------------
Message: 3
Date: Sun, 30 Dec 2012 20:01:01 +0000
From: Robert Troll <roberttroll hotmail com>
To: <elec-trak cosmos phy tufts edu>
Subject: Re: (ET) Controller current capacity
Message-ID: <BLU157-W17CA2D8CF1D85DE59277A1BA3D0 phx gbl>
Content-Type: text/plain; charset="iso-8859-1"
On 12/30/2012 10:09 AM, Robert wrote:
> Yes, Thanks. I'm surprised at the HP, I thought it would be higher
> as GE advertised the E20 as having the power of a 16 HP tractor.
> Back then ICE garden tractors had much lower HP, usually in the
> range of 5 to 8 HP. Of course, as many of you know electric motor HP
> and ICE HP are two quite different animals and this is where
> electric motors shine. Also torque curves are much broader for
> electrics.
The E20 motors have the TORQUE of a vintage Kohler 16hp tractor. ICE
tractors of that vintage generally have less HP, but more torque. I own a 72
JD140 which was the equivalent tractor of the day. My Deere is hydro. That
is power lost. The ET's of course are gear drive. Power wise they are
comparable as i have pulled equivalent loads with each.
I'm no expert, but I'd say youi'll need at least that much and probably
more. IIRC, when Alltrax was designing the ET controller, they started
with
a 200 amp (peak) current limit and after some testing increased it to 300
amps.
FWIW, most folks who design controllers have large piles of silicon that's
given its life in the design process. It seems to involve a lot of loud
bangs and, now and then, smoke and flames.
I just did a controller design and this is a little of that i learned
through lots of digging:
The Alltrax AXE/NPX series are direct replacements for the Curtis 1204.
Alltrax designed them to be more durable, and cheaper, then the Curtis.
Alltrax encases their controllers in epoxy to add vibration and weather
resistance. Think golf cart bouncing around a course all day in all kinds of
weather.
The Alltrax ET controller is an AXE series with the addition of field
programmable wiring CKT. The Alltrax/Curtis designs are made to work with
series wound or permanent magnet motors. That is why they work. Specifically
the Alltrax/Curtis do not freak out when they see voltage from the motor, as
you will see on the ET shunt motor, because they were designed to handle a
PM motor.
When i did my Curtis 1204 design, i mulled through the fuse requirements.
The reason why the controllers use a 250a fuse is because they are
automotive fuses that are not rated for 36v+. So the fuse is larger then
what would normally be required.
The standard ET power meter is rated for 100a. While i understand they are
inaccurate, every time i have had the occasion to "peg the meter" i loose
traction shortly thereafter. Even if you were to jam the tractor and lock
the rear wheels, the belts will eventually slip.
I just pushed 9 inches of snow with the Curtis and neither the controller,
nor the motor was warm. I have come to the conclusion that the "golf cart"
controllers are overrated for these machines. Any controller that can put
out 100a continuous should be more then enough to handle anything you can
throw at it.
I would start with a PM controller design of 100a continuous, and then add a
separate CKT to handle the tractors with the field. Which is basically what
i am running now. That would cover all the models. However to do it at a
price point that is lower then what is currently available i would think
would be a feat.
The Alltrax that Jim C currently sells i consider dirt cheap. I would also
not hesitate to install another Curtis or Jims Alltrax in my next
restoration.
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://cosmos.phy.tufts.edu/mhonarc/elec-trak/attachments/20121230/cb7a3e30/attachment.html>
------------------------------
Message: 4
Date: Sun, 30 Dec 2012 15:01:56 -0500
From: The CZ Unit <cz alembic crystel com>
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) Elec-trak Digest, Vol 10, Issue 201
Message-ID: <50E09DB4 8090102 alembic crystel com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 12/30/2012 10:17 AM, RJ Kanary wrote:
The big Klixon? mounted on the traction motor has all the loads
with the exception of lighting and the lift in series with it. It kills
everything, not just the traction motor.Additionally the thermal limiter
in the field windings protects the motor only by opening the RTN
circuit.With that thought in mind,that Klixon's rating may not reflect
what the traction motor can safely draw.The E-20 tractor has a 125A
Klixon? the lesser tractors use a 100A model.
Does it? I think the big accessory system is driven off the battery,
although the klixon controls power for the contactor coil.
Chris
------------------------------
Message: 5
Date: Sun, 30 Dec 2012 15:47:44 -0500
From: RJ Kanary <rjkanary consolidated net>
To: The CZ Unit <cz alembic crystel com>, et
<Elec-trak cosmos phy tufts edu>
Subject: Re: (ET) Elec-trak Digest, Vol 10, Issue 201
Message-ID: <50E0A870 3090307 consolidated net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I really should look at the diagram before depending on a 58
year old brain. I repent in sack cloth and ashes. I was less correct
than usual. <VBG>
Every thing else dying is a result of being a very large OPEN
in the positive side of the control circuit, since it it tapped off at
the armature circuitry.
RJ
On 12/30/2012 3:01 PM, The CZ Unit wrote:
On 12/30/2012 10:17 AM, RJ Kanary wrote:
The big Klixon? mounted on the traction motor has all the loads
with the exception of lighting and the lift in series with it. It
kills
everything, not just the traction motor.Additionally the thermal
limiter
in the field windings protects the motor only by opening the RTN
circuit.With that thought in mind,that Klixon's rating may not reflect
what the traction motor can safely draw.The E-20 tractor has a 125A
Klixon? the lesser tractors use a 100A model.
Does it? I think the big accessory system is driven off the battery,
although the klixon controls power for the contactor coil.
Chris
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak
------------------------------
Message: 6
Date: Mon, 31 Dec 2012 03:23:12 +0000
From: "Konstanty, Walter (GE Energy Management )"
<Walter Konstanty ge com>
To: "Brian E. Haines" <bhaines nycap rr com>,
"elec-trak cosmos phy tufts edu" <elec-trak cosmos phy tufts edu>
Subject: Re: (ET) motor ratings
Message-ID:
<001DBB9ACA41D24DBF8D6AB7D09197DD18D1B033 ALPURAPA04 e2k ad ge com>
Content-Type: text/plain; charset="us-ascii"
Interesting comments and thoughts..... figured I'd add some more.
When METI designed and built the "modern" Elec-Trak a few years ago we
used a programmable GE golf cart controller from FSIP (Flight Systems in
Reading PA). It was designed by a friend of mine and I was able, with his
help, to program the E-20 motor into it and it worked well. METI sold some
repower kits which were ready to go at the time. METI closed down due to
the 8 founders all being remotely located and the cost of trying to
manufacture a great machine cheap enough for a limited market. It may be
starting up again by one of the founders in Minneapolis.
At any rate, it is a good controller but did not regenerate but would
field pulse to hold the tractor on a hill at standstill. Once you hit the
accelerator you were at the mercy of the gas pedal and brakes.... I've
learned to deal with mine and have not had a single issue in 4 years of
using it. I can hook my laptop to it and watch volts/amps/field... etc.....
but, to use it "wisely" you need a tach on the motor and be able to program
it and I'm not sure that (programming capability) is available to the
general public. Remember, it is a high amp golf cart controller (36/48 volt
too). They program golf carts for hills or flat courses by varying current
ramp slopes and limits. GE/FSIP also makes EV controllers and a
regenerating one but it is also high amp capability and overkill for an ET.
On the METI tractor we used a motor which was larger and had much more
torque but we also had a locking differential if you wanted to impress your
friends with wheel stands or trac
tor pulls.
Series motors lack finesse and control that shunt or compound motors
have. You get more use of a shunt/compound motor because of field control
and field weakening for higher speed. Controllers are different too for
that reason.
The simplicity of the original ET control to regenerate is harder to
duplicate with a solid state control because you need a reverse bridge also.
FSIP has a ton of experience in EV controls and is a good source of
information - www.fsip.biz
...Walt
-----Original Message-----
From: Brian E. Haines [mailto:bhaines nycap rr com]
Sent: Saturday, December 29, 2012 9:56 PM
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) motor ratings
Yeah, I too would agree with David's post. An all around controller, that
would work with any ET motor would be a bear to create.
If I were to make a few suggestions:
1) Design a PWM controller for E15, and E20 class motors. The
controller would be identical between E15 / E20, and would cover a large
subset of tractors.
2) Integrate a 36VDC->12VDC circuity for the lights/lift/misc.
Besides being really handy it would also help issues with taping mid string
that could cause power to flow back into the controller in strange ways.
3) Integrate a second PWM circuit for 36VDC-> 120VAC . It wouldn't
have to be that robust, a modified sine wave, with a max of 10a....That
would be MIGHTY handy.
There have been posts of using expressPCB to create the first two (above).
I can find a link to a pure sine inverter design document(If anyone wants
it). It had the theory and design notes. Sadly my skills don't go quite
that far.
Someone with more chops may blast me out of the water on this one, but
I wonder if it might be possible to design a microprocessor controlled
controller for which the firmware was user-uploadable. Then all the
manufacturer would have to do is develop a new field map or control
algorithm for each motor the users wanted.
A NAND flash could do that.
http://www.micron.com/products/nand-flash
Run a tiny embedded linux core and read/write the settings to your heart's
content. :) But that's the programmer in me talking.
B
On 12/29/2012 1:31 PM, David Roden wrote:
On 29 Dec 2012 at 11:23, Bill Alburty wrote:
We need a controller which will work on all types of DC motors;
namely, series wound, shunt wound, compound wound, and all the other
combinations.
I'm not an engineer, but my impression is that this is a pretty tall
order.
Pairing a motor and controller is not a trivial process.
In particular, separately excited motors need a customized field
current profile, different for each motor. You may be able to find a
compromise that will work with several similar motors from the same
manufacturer (the Alltrax ET controller works OK with most ET
wound-field drive motors, AFAIK). But I think that once you get into
more dissimilar motors, the controller's designer has to consider each
motor's behavior separately.
Series motors seem to be more forgiving, but you can still run into
compatibilty problems, even beyond whether the controller can handle
enough current to run the motor in its intended use.
For example, certain Curtis controllers need more inductance than some
Advanced DC motors provide. Their current limiting doesn't work right
with those motors unless you add a series inductor. This is why more
recent Curtis road EV controllers reduce their chopping frequency to
the audible range at low duty cycles - it gives the current limiting
circuitry more time to respond.
Someone with more chops may blast me out of the water on this one, but
I wonder if it might be possible to design a microprocessor controlled
controller for which the firmware was user-uploadable. Then all the
manufacturer would have to do is develop a new field map or control
algorithm for each motor the users wanted.
However (here I am attacking my own idea), doing somethng like this in
a timely manner - so you weren't waiting months or years for your
firmware - would, again, be a nontrivial process. It'd require a long
term commitment from the designers. And at engineers' salaries, I
don't think it would be too compatible with a price that most of us would
want to pay.
It would be great to have someone design such a controller as a
volunteer, but would he want to support it long term, generating yet
another profile for yet another user for years to come? I think the
best chance for such an enterprise would be if we could find a large
community of qualified developers to work on the project, something
like some of the Linux variants have. Maybe with open specs, we could
develop a user community to support such a controller.
I question whether we have enough EEs in the ET world to make such a
project fly. Ffor this to work, I think the controller would have to
also be applicable to other machines more common than the ET. Maybe golf
cars?
NEVs? What else?
The market size is an ongoing problem with ETs, just as it is with
hobbyist road EVs. I suspect that the reason we have the Alltrax ET
controller at all is that Steve Richardson owned an ET, worked for
Alltrax, and wanted a modern, customized controller for his tractor.
Given the market size, I can't imagine Damon making it a priority
otherwise.
While it would be great to have a DIY / open source option, I would be
very impressed if a controller of any kind, DIY or otherwise, could be
made to support "all types of DC motors" - especially while costing in
the hundreds rather than the thousands of dollars.
David Roden - Akron, Ohio, USA
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Note: mail sent to the "etpost" address will not reach me. To send me
a private message, please use the address shown at the bottom of this
page : http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = =
= = = = = = = = = = = = = =
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak
------------------------------
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak
End of Elec-trak Digest, Vol 10, Issue 203
******************************************