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Forum Index : Electronics : inverter build inductor sizing

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stockleys
Regular Member

Joined: 21/06/2019
Location: United Kingdom
Posts: 54
Posted: 09:13pm 17 Mar 2022
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hi all

its beena while since i last posted on here.


i am looking to build a low frequency inverter  24v 3kw 230v.

i already have the aerosharp 3kw transformer and re wound it for 13v,

i have a board coming from aliexpress.

now the inductor recomended for the board is 47uh, but the diagram on the listing shows 48v, also, i cant seam to find an inductor of 47uh.      

i have found one that says its for 24v 3kw but is 25uh
or a 48v 3kw at 45uh,

which size would you recomend i get?


many thanks in advance
 
Godoh
Guru

Joined: 26/09/2020
Location: Australia
Posts: 372
Posted: 01:20am 18 Mar 2022
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Inductane doesn't have much to do with voltage from what i know.
I have a couple of inverters that are 24 volt and 3kw. I used a 65mm E core ferrite inductor core and wound 4 turns of heavy cable through it.
Not totally scientific but they inverters work well and don't draw much idle current.
Unfortunately the man to ask no longer comes to the site.
If you are getting a chinese 8010 based board there are a couple of modifications that help make them blow up proof.
I am not sure where they are on the site but they involve stopping the over current circuit from working. The boards have two different overcurrent protection circuits that can fight each other and cause them to blow up.
The easiest way I know of is to bend pin 1 of the 8010 board out so it does not make a connection at all.
Otherwise there are a couple of resistors and a small chip (LM393 I think) to remove.
Hopefully someone more knowledgeable will let you know more.
Pete
 
Revlac

Guru

Joined: 31/12/2016
Location: Australia
Posts: 960
Posted: 01:58am 18 Mar 2022
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stockleys, If you have the spare time to dig around through the forum you can find several examples about making your own choke with  aerosharp choke cores, if you have an inductance tester on hand it will make the job a lot Easier learning experience and be happy with the DIY result.

  Quote  i have found one that says its for 24v 3kw but is 25uh
or a 48v 3kw at 45uh,

It has been said that more is better, but better to have some than none at all,
Also check the current rating on the advertised chokes, see if they are up to the task.
Cheers Aaron
Off The Grid
 
noneyabussiness
Guru

Joined: 31/07/2017
Location: Australia
Posts: 506
Posted: 06:26am 18 Mar 2022
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don't touch the eg8010's pins, oztules rigorously tested it and it works fantastic... you will need to jump pins 7 to 8 and 1 to 4 on the 393 op amp.. also put a 18v tvs diode on the gates of the mosfets,  at least 1 on each " bank " of mosfets..

as for the inductor, at least 3 turns on a ferrite toroidal core is sufficient,  if warp was around he could talk you through a " proper " one..

as has been stated,  there is plenty of info if you search up setting these boards up, once set up they are almost indestructible...
I think it works !!
 
nickskethisniks
Guru

Joined: 17/10/2017
Location: Belgium
Posts: 405
Posted: 09:59am 26 Mar 2022
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The best advice I got in the past was something like this:

Use the biggest core you can find/afford and put on as many turns you can, make sure you use wire that can carry the current.
After this you can adjust the airgap until you reach your desired inductance.

I think many of us used around 50uH as a good value, more is possible and some did. But in my case, the higher I went the more the waveform was disformed.  
If you want to take it to perfection you will want to have a high enough saturation point of the inductor, that way the inductor keeps it's inductance value during operation.
 
tinyt
Guru

Joined: 12/11/2017
Location: United States
Posts: 430
Posted: 08:55pm 29 Mar 2022
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Dug up picture of my EGS002 mod.

 
noneyabussiness
Guru

Joined: 31/07/2017
Location: Australia
Posts: 506
Posted: 05:23am 30 Mar 2022
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seems unnecessarily difficult.. seriously,  jumping  pins  1 to 4 and 7 to 8  on " U4 " will do the same thing... but in addition,  the original " instant " current control of the eg8010 will continue to work if need be... why we had to remove the lm393 in the first place,  it would " fight " the eg's current control and you would cause spurious drive signal to mosfets causing instantaneous combustion..
I think it works !!
 
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