Author Topic: excel tool for calculating axial flux generators  (Read 65457 times)

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ChrisOlson

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Re: excel tool for calculating axial flux generators
« Reply #33 on: April 22, 2010, 04:16:56 PM »
I just started experimenting with the spreadsheet - I will agree, it's a great quick reference, but I wouldn't stake money on it.  The CP is always a slippery figure.  In my measurements (flawed as they are) I see TSR go up and down, CP go up and down, and plotting TSR versus CP makes a wild scatter of points through which no line may pas

Stephen, try the version of the sheet I attached.  I made some changes because there's several things wrong with it.  Firstly, the output of a generator is based solely on it's rpm/open AC volt, how many rpm it's turning, and what the resistance is it has to push against.  The rpm the generator is turning at depends on the Cp and actual TSR of the engine (blades) that's driving it.  This sheet doesn't take that into account anywhere.  However, Max's calculations seem to come out pretty close regardless, so I didn't mess with that part.

The things I did:
  • changed the entries so people who use English units of measure can enter in feet, inches, mph, etc.
  • changed how the stator and coil dimensions are figured. This took a bit of trial and error but I finally decided to go back to the coil winder dimensions because that's what determines the size of the coils and the subsequent size of the stator/mag rotors
  • added an entry for the resistance of the wire run
  • on sheet 2 there's a now a column called "Cp factor" - if you put 1 in every field the sheet will use a constant Cp. However, you can now change it to fit how your blades perform by entering the decimal equivalent of the percentage of max efficiency of the blade profile.
Too many other little changes to mention, but I played with it awhile last night and I think it's closer than it was (assuming you know how your blades perform)
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Menelaos

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Re: excel tool for calculating axial flux generators
« Reply #34 on: April 22, 2010, 06:20:38 PM »
Hello Again,

I was busy with my messed up stator the days...sorry for not replying.

Thanx for editing the tool. I might change the power section but I think this is not very important. Important for me is to figure out the right number of turns and the resistance and to have an idea of how big the whole machine will turn out.

U might be able to give me advice on another topic I will open a threat for...

LG

Max

DanielCV

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Re: excel tool for calculating axial flux generators
« Reply #35 on: April 30, 2010, 05:13:00 PM »
Hello Chris Olson,

I was trying to register in this forum for several days, but only now that registration is open, I think the admins have had some problems here.

I have seen your modifications and like them very much.

Only a pitty that you didn´t use our last version to make your own modifications, as we have imporved many things already, before you made your modifications.

You can download our latest version here: http://www.nadaparasiempre.com/hobbies/wind-energy/generator/index.html

Maybe if you could then again make your modifications on our latest version 1.3 and so we could then upload version 1.4 German and English again, as both have improved then a lot ?

But I think, it would be better to make two English version separatley: 1 for metric version and one for inches, it is much easier to handle then.

Best regards, and thanks for help !
Daniel


ChrisOlson

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Re: excel tool for calculating axial flux generators
« Reply #36 on: April 30, 2010, 05:43:28 PM »
Only a pitty that you didn´t use our last version to make your own modifications, as we have imporved many things already, before you made your modifications.

Hi Daniel.  I have downloaded your latest version and will switch it to English units of measure when I get time.  I will re-upload it back to this thread.

Thanks for a great tool!
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Chris

DanielCV

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Re: excel tool for calculating axial flux generators
« Reply #37 on: May 01, 2010, 04:45:08 AM »
Hello,

making a second version for inches is not a big deal I think - it´s just changing labels and voila !? I wil just do it now and upload it also.

The most important would be to get the extra calculations to be added to our latest version, as I like very much the following things you added:

- open voltage calculation
- changes made to efficiency calculation and graphs inlcuding the cp factor on sheet 2 and 3
- entries for resistance of wire run - are they better calculations then before ? could you please explain why ?

Not needed:
- maximum that will fit for coil thickness, as in our latest version we have added a visual function for the results to be displayed red when it does not fit, inlcuding 2 more variables as you will see.

Thanks for your productive colaboration !

Best regards,
Daniel

DanielCV

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Re: excel tool for calculating axial flux generators
« Reply #38 on: May 01, 2010, 05:26:18 AM »
Now I uploaded also the english units version - just need stil to adjust the calculations for the weight of wire in oz instead of grams...

DamonHD

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Re: excel tool for calculating axial flux generators
« Reply #39 on: May 01, 2010, 06:59:52 AM »
Except that "English" units are usually "US" units; and in England we mainly use metric anyway...  %-P

Rgds

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bob golding

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Re: excel tool for calculating axial flux generators
« Reply #40 on: May 01, 2010, 02:45:34 PM »
Except that "English" units are usually "US" units; and in England we mainly use metric anyway...  %-P

without sounding too pedantic i would  venture that the correct terminology is imperial.

Rgds


bob golding
if i cant fix it i can fix it so it cant be fixed.

DamonHD

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Re: excel tool for calculating axial flux generators
« Reply #41 on: May 01, 2010, 02:59:00 PM »
Well, even that "Imperial" would be the "British" Empire as was...  Those units are as English as Chicken Tikka Masala is Indian!  B^>

Rgds

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ChgDiv

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Re: excel tool for calculating axial flux generators
« Reply #42 on: July 26, 2010, 11:10:57 AM »
Max,

I've downloaded your excel workbook.  It looks like a great tool.  I am currently in the process of building an axial flux and there are a few items in reference to the coil dimensions that I am not clear on.  Do you have any kind of go-by for the input parameters?  I have attached a pdf of my design FYI.  End product has so far been the same as the design with the exception of the number of turns on my coils.  I'm at 260 instead of 389. Due to lack of foresight i did not allow extra space to facilitate 'random' winding of coils.  As a result i slowly wound the coils to optimal density.  The actually coils really look like the design. I did not know what to enter into the density factor for my coils on your spreadsheet. The magnets are 50.8mm X 25.4mm X 12.7 mm N42 grade.  I do not have a prop design as I have not decided exactly what the alternator will be used for.  Considering hydro power.  Anyway can you explain the dimensions in section 2 and also the density factor and wires in hand in section 5.  Any thoughts or suggestions are welcome as well.

Thanks

ChgDiv

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Re: excel tool for calculating axial flux generators
« Reply #43 on: July 26, 2010, 11:28:08 AM »
Max, 

My apologies for the SI units.  Its what i grew up with...Trying to change my ways haha.

awk

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Re: excel tool for calculating axial flux generators
« Reply #44 on: August 01, 2010, 01:34:18 AM »
   
        @Menelaos
 
       
            does your caculator work on round shape magnets?
         
             i have round shape magnets i am working an axial flux but don`t know about what gauge and # of turns i have exp many wires but no result.

thanks

XXLRay

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Re: excel tool for calculating axial flux generators
« Reply #45 on: August 03, 2010, 04:15:15 AM »
Menelaos is on vacation (and without internet) for the next weeks. Thus his answers might take a while.

joseba1

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Re: excel tool for calculating axial flux generators
« Reply #46 on: October 13, 2010, 07:05:23 PM »
Thanks Menelaos,  I've been strugling with this stuff for a couple of months, reading things way over my head and was hoping for something that I could use so I wouldn't have to re-learn calculus.  I'm likely to make mistakes but at least I'll have a good starting point.  Many thanks.

 

Spotnz

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Re: excel tool for calculating axial flux generators
« Reply #47 on: February 11, 2014, 09:17:04 PM »
hi,

I've just downloaded & translated V1.7 into english. With a copy ( hopefully ) attached

david
windy wannabe

lifer

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Re: excel tool for calculating axial flux generators
« Reply #48 on: March 16, 2014, 04:06:55 PM »
I need some help in the designing process of a PMG (for a VAWT wind turbine) so here's my questions:

1. I'm gonna use a transmission system so I want to run the generator at higher speed (rpm). Basically, I want to run it at least at 600rpm. I'm using this (great) tool to do some calculations but I'm not sure what values to enter for this specific situation. If I choose a wind speed of 20m/s, a TSR of 6 (it will be a VAWT turbine) and a diameter of 3.5m (HAWT blades diameter correspondence) I get 650 RPM. Are this calculations correct for further dimenssioning steps?

2. How to calculate the maximum rated power for the generator? Is it dictated by the rated current of the coils wire size? In this case, what "current before/after rectifier" means? Total output current or the single phase current (for a 3-phase generator)?

Any answer will be greatly appreciated.

StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #49 on: August 31, 2015, 03:40:43 PM »
Hello,

I am tranlating the excel sheet to a C# application with addtional documentation about the used formula's.

I would like to know what the formula is behind the calculation of the magnetic flux density? is there a referece?

=magnet grade-((magnet grade*(air gap/(2*magnet thickness)))*0,5)

The problem is I've found multiple sources for calculating the magnetic density (http://www.supermagnete.de/eng/faq/How-do-you-calculate-the-magnetic-flux-density (with excel file)):

http://www.supermagnete.de/docs/supermagnete_flux_density_eng.xls

Hopefully I can post an beta soon (with documentation).

With best regards,

JR.


« Last Edit: August 31, 2015, 03:48:31 PM by StirlingEngine »

SparWeb

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Re: excel tool for calculating axial flux generators
« Reply #50 on: August 31, 2015, 10:22:09 PM »
Hello Stirling,
Welcome to the forum.

I looked at the site you linked (thank you for that!) and it seems to be a detailed calculation of the average flux density at any point near the face of the magnet, given the geometry of the magnet and the remanance in the material.  The formulas can be derived from the basic magnetic principles found in a university physics textbook, and a bit of calculus.  The other formula attempts to give you the same result, but skips many details about the magnet's properties and geometry, by making a lot of empirical assumptions.  It is an approximation, and there are many other approximations in the spreadsheet besides it.  Most of them are OK for the hobbyist's needs.  If you don't need the exact formula, the approximate one is OK.

Here's another site with on-line calculations:  http://www.kjmagnetics.com/calculator.asp

You only need a reference for each formula if this project becomes your graduate physics thesis, in which case, you should probably do better than we can!
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #51 on: September 02, 2015, 02:48:34 AM »
Hello SparWeb,

Thanks for the reply!

The Excel sheet is indeed intresting. However, the outcome does not match the outcome of the axial flux calculator excel sheet?

I don't really need a reference for the formulas. I only would like to know if there is a (scientific) explenation for the formula (just me being curious and wanting an explenation for everything in life ;)).

JR.

Mary B

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Re: excel tool for calculating axial flux generators
« Reply #52 on: September 02, 2015, 06:22:38 PM »
read here http://www.fieldlines.com/index.php?topic=143174.0 there was also an earlier post with a spreadsheet called number of turns but I can't find it.

StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #53 on: September 10, 2015, 03:41:55 PM »
Hello,

I've converted all the code to C#. I used a lot of formulas from an article and the following book: "Axial flux permanent magnet brushless machines".

Now I am in the proces of writing unit tests ( to check the calculations) and creating a GUI. I still have to add several things like coil resistance and coil inductance. I will also add an graphical view of the coil dimensions, rotor and stator layout. I will also add an iterator so one variable can be chaged within a range (100 steps) to see (graphical) the influence.

Any other features?

If people are intresten I can post an beta version of the program and host the code on github?

I am also making a tutorial on how to use the designer and the background of the formulas (with examples).
« Last Edit: September 10, 2015, 03:48:59 PM by StirlingEngine »

SparWeb

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Re: excel tool for calculating axial flux generators
« Reply #54 on: September 15, 2015, 02:53:59 PM »
I would definitely take an interest in your results.  Running iterations would also be a big plus!

You should declare that your analysis is designed to expect a MPPT controller at the turbine output, or so it seems looking at your parameters list. 
You may also add the transmission line from turbine to controller, as the distance of wire can add a significant voltage drop on the line.

You should ask someone who knows more about MPPT controllers than me, but I believe they can be programmed to vary the load on the turbine so that the TSR varies.  It looks like you may be accounting for this already in your input parameters, but there are details about the way different controllers work that may change the effect.

I would like to see a summary of resistance losses at the target wind speed & power.  This would help when considering the amount of heat that must be dissipated.
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #55 on: September 15, 2015, 04:44:11 PM »
Good to hear :)

First of all I would like to say that the Excel tool is great. However, I am in the process of designing an axial flux PM generator to be driven by my beta stirling engine. I usually do a litrature study before I start building stuff. In this process I usually write a design tool to make designing and checking of the data more easy and also to learn about the subject.

My starting point is an article I've found on the internet:

Axial Flux Permanent Magnet Generator Design for Low Cost Manufacturing of Small Wind Turbines by
K.C. Latoufis, G.M. Messinis, P.C. Kotsampopoulos and N.D. Hatziargyriou.

This article describes the calculations pretty good!

For the tool I will also include the use of a turbine. This because I would like to contribute to the community.

I also think that the output source should be configurable (inverter, battery, etc..). The problem is that I just started on this subject an will need input of the community!

Anyway I will make a new forum post for the designer with a link to the executable, github repositry and documentation.

I this way the community can discuss the program and calculations and propose changes.

rsskarthikeyan

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Re: excel tool for calculating axial flux generators
« Reply #56 on: September 18, 2015, 09:58:18 AM »
Axial Flux Permanent Magnet Generator Design for Low Cost Manufacturing of Small Wind Turbines by
K.C. Latoufis, G.M. Messinis, P.C. Kotsampopoulos and N.D. Hatziargyriou.

Hello sir,
              I started with same article , but i have found some mistakes on it. Kindly tell me their calculations are right ? i have some doubts on calculation of "Maximum current density"




Thank you
               
               

StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #57 on: September 18, 2015, 05:31:03 PM »
Hello rsskarthikeyan,

The article contains a few mistakes... However, the calcuations are done right. What are your doubts on the calculation of the current density?


SparWeb

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Re: excel tool for calculating axial flux generators
« Reply #58 on: September 19, 2015, 07:45:01 PM »
I look forward to it, Stirling.  Thanks.

Thanks, also for the reference.  I'll look that up now!
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
www.sparweb.ca

rsskarthikeyan

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Re: excel tool for calculating axial flux generators
« Reply #59 on: September 23, 2015, 12:08:16 AM »
Hello rsskarthikeyan,

The article contains a few mistakes... However, the calcuations are done right. What are your doubts on the calculation of the current density?

I cannot get the values as stated on this article. I'm getting the maximum current density values around 48 A/mm2. I think its 10 times higher than the actual. Can you check my calculation if i send here

StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #60 on: September 23, 2015, 03:08:00 AM »
This post is about the Excel tool and has nothing to do with the article I used for my tool!

Maybe it is better to continue this conversation here:

http://www.fieldlines.com/index.php/topic,148812.0.html

Anyway, what values did you use for:

Iacmax
Sc
Kf
Wc
Tw
Nc

Regards


rsskarthikeyan

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Re: excel tool for calculating axial flux generators
« Reply #61 on: September 23, 2015, 06:53:07 AM »
This post is about the Excel tool and has nothing to do with the article I used for my tool!

Maybe it is better to continue this conversation here:

http://www.fieldlines.com/index.php/topic,148812.0.html

Anyway, what values did you use for:

Iacmax
Sc
Kf
Wc
Tw
Nc

Regards

 I'm getting the following values,
1.1*P-nominal/(3*Ef-nominal)*ἠ=  Iacmax= 48 A/mm2
Sc=7.16941E-07
Kf=0.55
Wc=0.313786028m  actually 31.54mm in that article
Tw=0.014m
Nc=337

StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #62 on: September 23, 2015, 07:27:56 AM »
Iacmax = (3000*1.1)/(3*286*0.9)
Iacmax = 4.27

Sc = ((0.55 *(0.03137*1000)*(0.014*1000))/337
Sc = 0.7167

Jmax = (Iacmax / Sc) = 4.27/0.7167 = 5.95

Dc = 0.955

Can you give me more data about the calculation of Wc (0.313786028)? I get 27 mm? What values do you use?

And yes, there seems to be a calculation error in Wc (factor 10)!

Regards

rsskarthikeyan

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Re: excel tool for calculating axial flux generators
« Reply #63 on: September 23, 2015, 07:34:17 AM »
Iacmax = (3000*1.1)/(3*286*0.9)
Iacmax = 4.27

Sc = ((0.55 *(0.03137*1000)*(0.014*1000))/337
Sc = 0.7167

Jmax = (Iacmax / Sc) = 4.27/0.7167 = 5.95

Dc = 0.955

Can you give me more data about the calculation of Wc (0.313786028)? I get 27 mm? What values do you use?

And yes, there seems to be a calculation error in Wc (factor 10)!

Regards

Here i have attached the calculation of AFPM generator using the following article..

Axial Flux Permanent Magnet Generator Design for Low Cost Manufacturing of Small Wind Turbines by
K.C. Latoufis, G.M. Messinis, P.C. Kotsampopoulos and N.D. Hatziargyriou.

StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #64 on: September 23, 2015, 08:22:37 AM »
.

StirlingEngine

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Re: excel tool for calculating axial flux generators
« Reply #65 on: September 23, 2015, 08:23:35 AM »
Hello,

I have checked your sheet and there are some incorrect values in it (efficiency 0.4 instead of 0.9, Coils per phase = 2 instead of 5).Hopefully I will post some documentation of my Axial Flux designer online:

http://www.fieldlines.com/index.php/topic,148812.0.html

There will be example calculations included explaining these formulas.  Hopefully you can work from there.

Any oter question ask in that post please (http://www.fieldlines.com/index.php/topic,148812.0.html)!! This post is (again) not about his subject.

Regards.