# [EVDL] Controller/Motor inductance



## EVDL List (Jul 27, 2007)

Do you know how much extra inductance this might add? 

Stephen Chapman




> storm connors wrote:
> >
> > You may be already aware of this which I just got from EVA:
> >
> ...


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## EVDL List (Jul 27, 2007)

----- Original Message ----- 
From: "enganear" <[email protected]>
To: <[email protected]>
Sent: Saturday, September 19, 2009 12:14 PM
Subject: Re: [EVDL] Controller/Motor inductance


>
> Do you know how much extra inductance this might add?
>
> Stephen Chapman
>
>


> > storm connors wrote:
> >>
> >> You may be already aware of this which I just got from EVA:
> Hi EVerybody
> ...


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## EVDL List (Jul 27, 2007)

> Bob Rice <[email protected]> wrote:
> > Hi EVerybody
> > Hmmm? Makes me wonder how the "Light Bulb " test can work for test=
> ing
> ...


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## EVDL List (Jul 27, 2007)

> storm connors wrote:
> >> Make a coil of 2/0 cable using about 10 ft of cable by wrapping it
> >> around a coffee can or PVC pipe; then wire tie the coils together.
> 
> ...


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## EVDL List (Jul 27, 2007)

10 foot of 2/0 cable should weigh about 21 pounds. That's a lot of 
weight to be secured by only two motor bolts. Does anyone have any 
experience in securing such a coil?



> Lee Hart wrote:
> > storm connors wrote:
> >
> >>> Make a coil of 2/0 cable using about 10 ft of cable by wrapping it
> ...


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## EVDL List (Jul 27, 2007)

From: Peter Eckhoff <[email protected]>

>10 foot of 2/0 cable should weigh about 21 pounds. That's a lot of 
>weight to be secured by only two motor bolts. Does anyone have any 
>experience in securing such a coil?

Wrap it around the motor? 

It might work. On the plus side, the iron core provided by the motor will significantly increase the inductance, so you need less wire. On the negative side, the coil will create a magnetic field in the motor with its North pole at one end, and South pole at the other end. Magnetizing the outer iron case shouldn't matter, but I'm not sure you want the shaft to be magnetized.

Personally, I would not use an air-core coil. It takes too much wire, and copper wire is expensive. Instead, I'd get a bunch of small transformers. Cut the windings off, and use just their E and I laminations. Get a piece of flat copper buss bar that fits in the openings in the E laminations. Wrap it with tape or heatshrink tubing, bend it into a "U", and place the E laminations around it (one side of the busbar "U" in each E opening). Put a piece of tape or fish paper on top of the stack of E's, then put the stack of I-laminations on top of that. You want an air gap between the E's and I's because you are running DC in the coil.

A 12" piece of buss bar and a 3" to 4" stack of laminations should give you all the inductance you'd ever need.

--
Those who say it cannot be done should not interrupt the one who is
doing it. -- Chinese proverb
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net

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## EVDL List (Jul 27, 2007)

Interesting point. Given the added weight, is the improvement in performance
and/or range (assuming you're not doing this to solve a problem) justified?
That is, will the extra weight be enough to neutralize any expected
improvement?

- Peter Flipsen Jr
http://www.evalbum.com/1974



> Peter Eckhoff <[email protected]> wrote:
> 
> > 10 foot of 2/0 cable should weigh about 21 pounds.
> >
> ...


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## EVDL List (Jul 27, 2007)

I think 10 feet of 2/0 cable is closer to 4 lbs.



________________________________
From: SLPinfo.org <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Tuesday, September 22, 2009 12:54:09 PM
Subject: Re: [EVDL] Controller/Motor inductance

Interesting point. Given the added weight, is the improvement in performance and/or range (assuming you're not doing this to solve a problem) justified? That is, will the extra weight be enough to neutralize any expected improvement?

- Peter Flipsen Jr
http://www.evalbum.com/1974



> Peter Eckhoff <[email protected]> wrote:
> 
> > 10 foot of 2/0 cable should weigh about 21 pounds.
> 
> ...


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## EVDL List (Jul 27, 2007)

> Personally, I would not use an air-core coil. It takes too much wire, and copper wire is expensive. Instead, I'd get a bunch of small transformers. Cut the windings off, and use just their E and I laminations. Get a piece of flat copper buss bar that fits in the openings in the E laminations. Wrap it with tape or heatshrink tubing, bend it into a "U", and place the E laminations around it (one side of the busbar "U" in each E opening). Put a piece of tape or fish paper on top of the stack of E's, then put the stack of I-laminations on top of that. You want an air gap between the E's and I's because you are running DC in the coil.


Lee,
I'm having trouble picturing it.
Has someone done this and posted a picture on the web?

Thanks
Seth

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## EVDL List (Jul 27, 2007)

>> Personally, I would not use an air-core coil. It takes too much wire, and copper wire is expensive. Instead, I'd get a bunch of small transformers. Cut the windings off, and use just their E and I laminations. Get a piece of flat copper buss bar that fits in the openings in the E laminations. Wrap it with tape or heatshrink tubing, bend it into a "U", and place the E laminations around it (one side of the busbar "U" in each E opening). Put a piece of tape or fish paper on top of the stack of E's, then put the stack of I-laminations on top of that. You want an air gap between the E's and I's because you are running DC in the coil.



> Seth Rothenberg wrote:
> > I'm having trouble picturing it.
> > Has someone done this and posted a picture on the web?
> 
> ...


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## EVDL List (Jul 27, 2007)

Picture the core iron of a smallish transformer,
say all the laminations stacked on each other are a stack of about 1"
thick
while the width of each leg of the "E" shaped laminations is 3/4
while the length of the legs are for example 1.5" and the back
of the E as well as the length of the "I" are 3".
One "E" and one "I" together form a complete magnetic circuit
(the back of the E, the three legs of the E and the I) with 2
openings of about 3/8" wide and 1.5" long between the legs.

Now take the core laminations of some 5 tranformers with the same size
laminations.
Stack all "E" shaped pieces on top of each other and stack all "I"
laminations
on top of each other.
It should be a stack of about 4-5" high each.
If they have holes in the corner then you can run a 6" thin bolt through
the stacks
to keep them together.
Take the stack of E laminations and lay it with the back down, so the
legs stick up
and you see two openings, two long channels of 1.5" deep, about 3/8"
wide and 4-5" long.
Take the copper busbar, bend it in U-shape with the legs about 1" heart
to heart,
it should fit in the two channels between the legs of the E.
Wrap it in tape or heatshrink or whatever.
Put it in the E and fix the stack of I-laminations on top of the legs
with a piece of paper
between the E and I laminations. You can use 4 metal strips if you have
bolts in the
corners of the laminations - often you can re-use the original
transformer mechanics/mounting.

If the busbar had two holes in the ends, that is where you can now
attach wires/lugs.
Hope this clarifies,

Cor van de Water
Director HW & Systems Architecture Group Proxim Wireless
Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Lee Hart
Sent: Wednesday, September 23, 2009 8:45 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Controller/Motor inductance

>> Personally, I would not use an air-core coil. It takes too much wire,
and copper wire is expensive. Instead, I'd get a bunch of small
transformers. Cut the windings off, and use just their E and I
laminations. Get a piece of flat copper buss bar that fits in the
openings in the E laminations. Wrap it with tape or heatshrink tubing,
bend it into a "U", and place the E laminations around it (one side of
the busbar "U" in each E opening). Put a piece of tape or fish paper on
top of the stack of E's, then put the stack of I-laminations on top of
that. You want an air gap between the E's and I's because you are
running DC in the coil.



> Seth Rothenberg wrote:
> > I'm having trouble picturing it.
> > Has someone done this and posted a picture on the web?
> 
> ...


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## EVDL List (Jul 27, 2007)

Well you could use that formula that was posted and it is pretty exact for an
air inductor. 10 feet air inductor might get 10-13uH. My motor is a jack
heintz g29 and it had a very low inductance of in the 23 - 26uH
microhenries. I built an inductor just to move the vehicle last year and
believe it is a good design and very simple. Lee Hart totally gave me the
idea. I plan on building one more and getting rid of one made with zinc iron
laminated sheets of metal with holes drilled through it and wire wrapped
around it. The home made one over heats and not based on any real data for
15kHz DC. I remember each one measured around 150uH using an inductance
meter got on ebay. The results were impressive, but still not perfect. Take
off changed the motor from a huge jerk to a very small one and the curtis
controller didn't blow or get too hot. 2/0 wire was too thick to wrap
around the toroids, so I split it in two. Maybe you could try that extra
flexible 2/0 cable or use flexible 1 guage and simply combine inputs and
outputs to equal 2/0. 1/0 might work too and then add 4 gauge to it. I used
the micrometals .com T650-35 toroid as it was either that or T650-34 or
T650-63. These toroids are gigantic and would have liked to use a t650-63,
but was way too expensive. They have a program to help you decide for free
called MicroR_Jan12_2008.exe. During August 2008 I paid $133.93 with
shipping to Florida included for two t650-35 and the the t650-34 were a
little more. I am hoping it is a lot cheaper now. To order you have to
give them a call since they don't have online ordering. If someone calls
about the t650-35 please post how much they want for it as I need two more.
If your motor it simply borderline, then one might be enough. First measure
the coil inductance and calculate how much more you need. I don't think the
program computes correctly over 250amps. 150uH total should be enough, but
others should chime on this as I am guessing. 
Here is a picture of the T650-35 powder iron toroid
http://img19.imageshack.us/img19/2670/1000742i.jpg
Image of a very poorly made inductor, but using good cable + clear thick
tape and the results will be great. 
http://img19.imageshack.us/img19/1100/1000751i.jpg





Do you know how much extra inductance this might add? 

Stephen Chapman



-- 
View this message in context: http://www.nabble.com/Controller-Motor-inductance-tp25522761p25531352.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

> ampaynz1 wrote:
> > I built an inductor just to move the vehicle last year and believe it
> > is a good design and very simple... Takeoff changed the motor from a
> > huge jerk to a very small one and the curtis controller didn't blow
> ...


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## EVDL List (Jul 27, 2007)

Below is the original post (with a lot of follow-up)
that explains how it can be beneficial to add inductance
to a large motor with low resistance and inductance,
which can cause excessive spikes of current during the
"ON" times of a PWM controller.
When I try to measure the resistance of my 11" GE motor
then I can't even get a reliable reading on my
multimeter, because the contact resistance of the
probes is higher than the resistance of the entire
series motor, I get a 0.2 Ohm reading no matter whether
I measure with both probes on one motor terminal or
through the entire motor...

Anyway, I have a microwave transformer that I could
repurpose the core from to wrap a few turns of
"welding" cable through and add in series with the motor.

Comments? Good idea on an EV100 (EVT15) IGBT controller
that is running at about 2kHz?

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water  XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of storm connors
Sent: Saturday, September 19, 2009 8:47 AM
To: Electric Vehicle Discussion List
Subject: [EVDL] Controller/Motor inductance

You may be already aware of this which I just got from EVA:



With the large number of systems we sold last year, now in operation,
some customers (~1%) have run into some operating problems, such as a
periodic burp in the system. Dave Mosher of Custom Electronics has
determined that these problems were due to low inductance in the system.
Inductance can be added to the system by making an inductive coil.

The instructions are:

Make a coil of 2/0 cable using about 10 ft of cable by wrapping it
around a coffee can or PVC pipe; then wire tie the coils together.
Remove the coffee can-it is metal. Connect this coil between A2 and
S2 on the motor (CCWDE), replacing the existing short cable that
connects the field and armature in series. If the motor is set up for
CWDE, then the terminals will be A1 and S2. This coil does not need to
be beside the motor, so you have some flexibility in location. Use
quality lugs and heat shrink.

The addition of an inductive coil eliminated the operating problems that
these few customers encountered. We are fine tuning the existing
system. Adding an inductive coil to the motor circuit will be beneficial
for all of our customers, because it will decrease the heat in the
controller and motor and possibly provide additional range. To date,
the inductance coil has been implemented on a few vehicles with no
negative results.

--
http://www.austinev.org/evalbum/1059
http://stormselectric.blogspot.com/
Storm

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## EVDL List (Jul 27, 2007)

From: "Cor van de Water"
>When I try to measure the resistance of my 11" GE motor
then I can't even get a reliable reading on my<


to ge the motor resistance you need to pass a known voltage through
the motor and then measure the amps. The stand still resistance will
be quite different than when the motor is turning . You'll have to use
a low voltage and keep the motor form turning . If 1 volt passes 50
amps then motor resistance 1/50 ohms but you'll have to measure the
voltage right at the motor as the cables will also have some
resistance.

This said a 9 ' motor hooked to a 12v battery will pull about 50 amp
and spin about 2000 rpm , ( this is from memory awhile back ) the 11"
as I remember doing the same test seemed to spin slower which would
kind of make one thing that its resistance is higher , and would be
easier on the controller . but resistance and inductance I believe
come from different parts of the motor. So finding the resistance may
not really tell you that much.

Steve & Audrey
Your Green Shed Team
772-971-0533
Tomorrows Ride TODAY !
Visit our shop web page at: www.Greenshedconversions.com

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## EVDL List (Jul 27, 2007)

> Lee wrote:
> > However, your controller probably switches at around 15 KHz. The core
> of the microwave transformer was designed for 50/60 Hz, so its losses at
> 15 KHz will be substantially higher. You'll lose some power in core
> ...


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