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Forum Index : Electronics : DIY DC Boost convertor: 100+V, max 15A
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LadyN Guru  Joined: 26/01/2019 Location: United StatesPosts: 408 |
DIY DC Boost convertor: output specs 100+V, max 15A Does anyone here have a preferred design they like or even came up with themselves that can support an output spec 100+V (say 150V DC), max 15A (typically 5A w/15A surge)? If not, I will start reading up on an oztule's TL494 design here that could be a good candidate The input range is up for debate but since I control the input, I can try and make it whatever makes the design easy and efficient (probably needs to be closer to 100VDC than lower) The final objective is that I would like to add the ability to have a microprocessor control (in addition to the onboard TL494) a bunch of them in parallel (multiple of these DC Boost convertor load share in parallel) The output does need to have the ability to be adjusted 20%. So this means that I could be able to change the output between 90V DC - 130V DC with the typical voltage being 110V DC These would essentially be used to boost battery and PV Panel outputs and load share with rectified grid DC If any of you are interested in this, I would love to hear your thoughts!! |
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mackoffgrid Guru Joined: 13/03/2017 Location: AustraliaPosts: 460 |
I guess it depends on input voltage. If you desire an input of nominal 24V or even 12v if you think of truck / tractor batteries or your average 30 something volt solar panel - then some sort of push pull design might work better. |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Thank you for taking your time to look into this! My concern with such a high boost multiplier (24V dc i/p, 120V dc o/p, so 5x) is that the losses will probably be too high. This would complicate the design? To allow 1kW into the system, the input current would have to be a substantial 50+A! The battery pack will be 48V, but I can pair them to 2x = 96V. I think I might put the min. input voltage at 72V DC so that the 48V pair has some working area. I guess experience and failure will teach me what I should have done in the first place :D Do you have a preferred design in mind? |
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| mackoffgrid Guru Joined: 13/03/2017 Location: AustraliaPosts: 460 |
IMHO and relative inexperience of smps design, The beauty of a push-pull is that its easy, move any voltage to whatever voltage, its just a little inverter with a transformer. my 2 bobs worth  |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Oh, I see what you mean. A bridge design that pulses the primary of a transformer with the pulses out the secondary being rectified? The transformer won't have to necessarily be too big either depending on the switching freq. Did I get that right? (also you were too kind with "relative inexperience". Let's try complete inexperience!) If so, are there papers/articles about the efficiency of transformer based designs? |
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| mackoffgrid Guru Joined: 13/03/2017 Location: AustraliaPosts: 460 |
Several of the Mikes and Tony are far more experienced in smps than me. My goto controller is the sg3525 for push pull, I generally run it about 20khz because I usually don't care about size or pennies too much. I have only ever done relatively small stuff as in < 20w. The thing to watch is that you need to get fets that are at least 2 x the input voltage which is why I think its good for low to med voltage. Open to more clever ideas, Andrew |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
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| ltopower Regular Member  Joined: 08/03/2019 Location: United KingdomPosts: 64 |
There are some very cheap 1500W boost converters online, they seem to be around 90% efficient, 40A in 20A out limits, max V out around 90V. They are CC CV. Be warned they have a slight flaw, as they are intended for high inductance solar input. Hook up a battery to them set at a high voltage output and the initial capacitor surge passes through the FET's and blows them. Pre-charge the caps they are fine. The design of them also uses the -ve return for current sensing so if you try them in parallel the re-distribution of current through the -ve lines makes all but one of the units shut down. If your implementing current limiting where the current sense is done will need to be taken into account in relation to overall current flows. They could provide a starting point. |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Hi! If you are not talking about these ones, I would love to see a link or two :) |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
If you have 1.5Kw worth of solar panels, just connect them up to give 100v. I just cannot understand the logic of connecting so many panels in parallel for a low output voltage then trying to boost up the voltage ???????????? Cheers, Tony. |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
Hi LadyN, also not sure of the context or reasoning why you require a boost inverter, I have my panels series connected for 152 volts DC feeding into my mppt controller, the new controller will accept up to 250v so will be placing 5 in series. Of course high DC voltages are more dangerous and require appropriate DC breakers and vacuum relays for controlled disconnect switching, adds to the costs but better efficiency. Cheers Mike |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
These are good questions. It's VERY much possible I'm misunderstanding the details. I posted the question here: https://www.thebackshed.com/forum/forum_posts.asp?TID=11242&PN=1&TPN=1 |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Mike has the right idea, one or more strings of six panels in series. Open circuit voltage, 240v Max power voltage probably around 6 x 28v = 168v Dc voltage rectified direct from grid 110v x 1.414 = 155v Inverter design input voltage range possibly 140v min to 280v max. Cheers, Tony. |
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| mackoffgrid Guru Joined: 13/03/2017 Location: AustraliaPosts: 460 |
One reason why you'd run panels in parallel is if they where amongst trees etc. I have a natural water source and I'm not allowed to clear trees. So running panels in parallel will reduce hot spotting in the panels. |
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