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Forum Index : Electronics : Best design for chokes for 150V 45A MPPT - roll your own

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rogerdw
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Joined: 22/10/2019
Location: Australia
Posts: 852

Posted: 09:54am 29 Nov 2023

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Hi guys,

I'm at a stage of building chokes/coils for some 150V 45A charge controllers and while I've scoured the thread to see what might be the best configuration, I'm not 100% sure which way to go yet. Classic sign of procrastination I'm afraid.

I noted Bryan's choke with the heavy rectangular wire ... and Klaus's efforts using Aerosharp cores. But then I noticed Klaus mentioned that his run hotter than the main heatsink. And then Noneya's ferrite cores as well.

I do have a large heap of different Aerosharp chokes lying around, so suspect that is the way I should go.

For any of you who have built these things, and with hindsight ... what would you recommend as the best configuration, gauge of wire, number of turns and approximate inductance to aim for. Thanks.

Cheers, Roger

Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1344

Posted: 10:44am 29 Nov 2023

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Hi Roger with that dual choke I made using the large choke from the areosharp with 10 turns on each side I put on that first inverter I made using the ching board.

To test the inverter out I simply put a 2400 watt vacuum and a 1200 watt vacuum in the 240 volt sockets and turned them on together and both vacuums ran normally and the inverter didn't blink.

I used the probe on my temp gauge to see if my choke was getting warm and it didn't change temp at all while the load was going.

Now to get a good source of that thick wire mig welders are a good donor but it may prove some fun if they are lacquered in.

Cheers Bryan

Revlac

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Joined: 31/12/2016
Location: Australia
Posts: 1024

Posted: 10:53am 29 Nov 2023

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Chokes tested Pg 20 and 21
https://www.thebackshed.com/forum/ViewTopic.php?TID=12027&P=20

Cheers Aaron
Off The Grid

poida

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Joined: 02/02/2017
Location: Australia
Posts: 1418

Posted: 09:38pm 29 Nov 2023

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the test results

I ended up using one large Aerosharp core with 16 or so turns.
2 x 4.5mm2 for the winding.
I have no problems with heat or loss of efficiency

The 2 mppt controllers in service have delivered 10 MW.hr in total.
I am happy to say they have not needed to be rebooted or reset
in this time.

wronger than a phone book full of wrong phone numbers

rogerdw
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Joined: 22/10/2019
Location: Australia
Posts: 852

Posted: 12:25pm 30 Nov 2023

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Thanks for the responses.

Bryan, I am referring to the choke needed for the MPPT charge controller and not for an inverter. Sorry I probably wasn't all that clear.

Thanks for the reminder of that discussion Aaron, I had forgotton that section for some reason. It's too easy to get fixated on one area and not check everything else (well for me anyway).

And thanks Poida for those details, very helpful. Amazing track record and I just hope mine reach that milestone eventually.

I was trying to avoid having to spend a heap on ferrite formers, especially seeing I want to build 4 chokes eventually ... and I have a heap of Aerosharp chokes already, so will be handy to be able to use them. I reckon that's the way I will go for now.

Thanks once again.

Cheers, Roger

nickskethisniks
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Joined: 17/10/2017
Location: Belgium
Posts: 458

Posted: 08:45pm 30 Nov 2023

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Hi Roger,

For an indication for the inductance value, try this calculator:

https://daycounter.com/Calculators/Switching-Converter-Calculator.phtml

You can use 20% for inductor ripple, this is a good starting point. I personally use 3-4A/mm², I like stranded wire because it's easier to bend. But skin effect will only occur due to the ripple current, so if the inductance is high enough there is really no need for stranded wire. But there is no need to go nuts with the inductance.

If your not seeking for max efficiency just use what you have, otherwise use ferrite or sendust to make very efficient inductors with.
Edited 2023-12-01 06:51 by nickskethisniks

rogerdw
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Joined: 22/10/2019
Location: Australia
Posts: 852

Posted: 12:34pm 01 Dec 2023

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Thanks Nick, I'll have a play with the calculator and see if I can make any sense of it all.

Though I'm not all that fussed about efficiency at the moment, I just need to get these working and I can always fine tune them later.

Cheers, Roger

nickskethisniks
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Joined: 17/10/2017
Location: Belgium
Posts: 458

Posted: 01:10pm 01 Dec 2023

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rogerdw said Thanks Nick, I'll have a play with the calculator and see if I can make any sense of it all.

Though I'm not all that fussed about efficiency at the moment, I just need to get these working and I can always fine tune them later.

I'm talking about marginal gains compared to the nominal power so no worries.

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