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copperlogic
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Joined: 26/10/2016
Location: New Zealand
Posts: 4

Posted: 11:09pm 25 Oct 2016

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Hi There. I am really hoping someone can explain one or two things to me. I have ordered one of these things below off of aliexpress.It is a 12/24/36/48v inverter board driven by an EGS002. Different input voltages are achieved by changing one resistor on the board I intend to reconfigure it for 96v. I realise that the mosfets and capacitors will need changing for 96v. I have a stack of IRFP90N20D FETS. I bought them for a 10kW inverter that didn't make it past its first day. I replaced them once and then knew I was swimming upstream.
I still have both of its 52/240v 5kW transformers. They are about the only things in the contraption that I trust(35kg each). I'd like to try this sine wave board on one of them.
My questions: If I am able to sort the voltages to the driver module, 5v and 12v as and where necessary, will the new mosfets and 96v drive the 52/240v transformers as if nothing has changed? Is what I am looking to do with this board even doable?

https://www.aliexpress.com/item/1PC12V-24V-36V-48V-750W-1500W-2000W-3000W-Pure-Sine-Wave-Power-Frequency-Inverter-Board/ 32727677770.html?spm=2114.13010608.0.0.DW9DrL

Thank you.

oztules

Guru

Joined: 26/07/2007
Location: Australia
Posts: 1686

Posted: 05:20am 26 Oct 2016

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Yes... it is only the low voltage supply and the caps and fets that need to be looked at. The drivers can handle hundreds of volts.

.....oztules

Village idiot...or... just another hack out of his depth

copperlogic
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Joined: 26/10/2016
Location: New Zealand
Posts: 4

Posted: 09:26am 26 Oct 2016

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Thank you for that. I bought the cheap one first to "test drive" Nice to hear that.
A better model is in the post now too. 24 Fets. Is there any chance the drive will battle to drive 24 much higher powered FETS? Would it be necessary or not to amplify the signal for reliability at least?

https://www.aliexpress.com/item/1PC-24V-36V-48V-60V-2000W-3000W-4500W-5000W-Pure-Sine-Wave-Power-Frequency-Inverter-Boar d/32697164098.html?spm=2114.13010608.0.0.2VzEaQ

It appears that the 12v power supplier is fed by a buck converter XL7015 Max 80v.
Presumably the 5 volt supply comes from there too?
Could A simple voltage divider to ground do the trick? or would it be better to replace the converter.

Thank you for your help oztules.

Matt.

oztules

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Joined: 26/07/2007
Location: Australia
Posts: 1686

Posted: 12:02pm 26 Oct 2016

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My guess is that the higher voltage fets will sport a thicker oxide layer, and so the capacitance will be lower per fet... so easier to drive... the capacitance of the gate will be a surface area x thickness equation in the end, and thicker oxide means less capacitance for the same area.

You may find that you can get 5 dollar isolated power supplies that will function in the voltages you are going to use with small changes perhaps. ( little wall warts)

The divider will work, but will be decent resistors... not sure of the current draw of the lv circuits, not much I would think.

If you use a few big transistors and zenners like I did on the ozinverter.. then that should do fine... but not the fan/s.

..........oztules

Village idiot...or... just another hack out of his depth

copperlogic
Newbie

Joined: 26/10/2016
Location: New Zealand
Posts: 4

Posted: 09:44am 31 Oct 2016

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Hi again. The 48v board for its 96V conversion is on its way. I have a question about the capacitors if that's OK? Both of the 5kW boards from the previous 10kW inverter have 90A 200V Fets with 160V 2000uF caps. I would like to use the same value Fets again in the new board as I have a heap of them spare. The old caps are pretty big. About 2" high and 1 1/2" in diameter. Is there any reason I won't be able to use these big caps again in the new board, other than their dimensions? Could they be overrated capacitance wise?

Looking at formulas for calculating ripple current makes me think I should go back to school. Is more capacitance a good thing? 2000uF seems high.

"If you use a few big transistors and zenners like I did on the ozinverter"
Please excuse my ignorance, but is this an addition to the driver or a pre-amp?

I clearly have a lot to learn.

Thank you.

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