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davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499
Posted: 06:21pm 13 Feb 2019
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Again about 1/2 the "stated power" when using 30VDC input.
LadyN, where is the current shunt on our units?
I'd guess our units would be struggling to get 400W without a fan.
LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408
Posted: 06:58pm 13 Feb 2019
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Very interesting. How does it achieve load regualtion without sensing the load current?
Would you happen to have a schematic of this supply? I can try and trace it by looking at the pictures but incase you already have it even better! :)
This looks like a UC3843 based PSU, different from the TL494, Am I correct?
If it was TL494 based, I would have ordered it right away. Want to minimize all the parts I have to know about.
The convertor is really dense and hard to trace without taking all the parts off but I tried to trace it and it seems to be right across the output load, that thick plated wire just by the output terminal.
davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499
Posted: 09:19am 14 Feb 2019
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It looks to me that that thick piece of wire senses the output current (in the negative output track).
I'll stick my finger on it when I get up to 70Volts and 7-8A and see if it gets hot!
BTW, I stuck with the ZVNL parts because I had to reduce R2 down to something like 10K or I couldn't get the "dynamic" range I wanted in voltage. With R2 at 10K you can still get >70V maybe even up to 80Volts across the JFETs.
hotwater Senior Member Joined: 29/08/2017 Location: United StatesPosts: 120
Posted: 03:14pm 23 Feb 2019
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Has anyone gotten this to work yet?
davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499
Posted: 01:08am 24 Feb 2019
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If "this" is getting PV diversion working with that Chinese SMPS, then the answer is a qualified yes.
The 2nd unit is for HW diversion in my caravan (trailer) working off 18Vmp panels. As Voc of the panels are 22V one has to keep the lower voltage limit to around 25Volts. It is a boost supply and doesn't like working below a 2Volt differential. So, with 25Volts and 75Volts at the top limit, this gives you crude "MPPT" tracking over a 9:1 power range. I have only one 150 Watt panel and when I increase it to 2 panels I can increase the upper limit up to 85-90Volts.
Now, with the first unit I am using 36Voc panels. So, the lower voltage limit can't be lower than 38-40V. As the upper voltage limit is still 85-90Volts one only gets about a 4:1 useful power range. Better that no PV load adjust but not brilliant.
During the summer I have a lot of unused PV going to waste. Next time I build a house I would just put up a few more panels, design a proper diversion system, no solar hot water and keep the woodburner.
Dave
hotwater Senior Member Joined: 29/08/2017 Location: United StatesPosts: 120
Posted: 06:07pm 05 Mar 2019
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This is what I have running now. Boost converter converted to run on 60+ volts by changing input cap. Used a couple zeners to change turn on of boost from 10 to 46V. This keeps the boost from coming on till sun is finally up. Board is a IR2153 design which is quite stable. This is going to camp on the second water heater. It doesn't use a boost converter there as it has a 2,000W 120V element.Edited by hotwater 2019-03-07
LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408
Posted: 02:58am 06 Mar 2019
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hotwater, brillitant!
Would you be OK if I created a new thread to try and understand your creation?
I would LOVE to make one, if you can help me.
So on the left is a DC CONVERTOR.
I am assuming it's a modified Boost converter that atleast has:
1. Its input capacitance voltage upgraded to handle 60+ volts. So it's probably directly connected to atleast two grid tie like PV Panels?
2. There's also another mod by the fuse. Is that just the zener mod to change turn on of boost from 10 to 46V? So below 46V it is in bypass mode and connects input to output?
On the output of that DC CONVERTOR you have a modified switch of some sort (possibly using the IR2153 as you mentioned?) that can be tuned using a VR
Is the panel meter measuring input power? If so, was it during the dawn or is it very cloudy today?Edited by LadyN 2019-03-07
hotwater Senior Member Joined: 29/08/2017 Location: United StatesPosts: 120
Posted: 01:44pm 06 Mar 2019
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The output board is a "300W inverter board" found on ebay for about $6 shipped. The relay which is totally useless has been removed in order to have a space for the mods. It keeps the capacitor bank at a fixed minimum voltage. It is sorta a wham bam regulator which is what many supplies are now. The world has moved away from PWM. This has a really minimum parts count.
davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499
Posted: 07:21am 22 Mar 2019
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More testing under low light conditions, with this particular board, has convinced me that I really haven't got it working properly.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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