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Excess solar power needs to be dumped into a lithium based battery (load). The battery's charging voltage is 54 V. The battery has protection for over and under voltage and upper current limt and that is not of concern.

This question asks for a circuit to make an adjustable current limiter based on a reference input voltage. The current limiting (i_l) changes as the voltage changes:

i_l = f(v)

Where f(.) is the limiting function implemented by the circuit and v is the controlling voltage and is in the range of 0.3 to 3 V. At v = 3 V, i_l is the maximum allowable current and is 35 A. At v = 0.3 V, i_l >= 0 A and thus as v is reduced, the current limit of the circuit is reduced.

Here is a block diagram : enter image description here

I am aware that off the shelf programmable voltage sources are available, which allow adjustable current limiting, however I would like to implement this circuit myself.

This question is how to implement a controllable current limiter based on a reference voltage.

winny
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Matt
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    Wasn't this not only [here](https://electronics.stackexchange.com/q/634929/38098) and closed but also perhaps earlier, as well? – jonk Sep 15 '22 at 22:08
  • It's not completely clear what the actual V I control and limit requirements are. Must it be constant voltage with a programmable current limit (at which point of course the voltage drops)? This sounds like a remote controlled 2 kW mains power supply, could you just [buy one like this](https://www.keysight.com/us/en/products/dc-power-supplies/ate-system-power-supply/n6900-series-advance-dc-power-supplies-1000w-2000w.html)? – tomnexus Sep 15 '22 at 22:13
  • Hey tomnexus, that programmable supply looks good. The current limiting should be from around 0A to 35 A. The input v would be from 0.3 to 3V. Probably but not necessarily with a linear mapping. Yes, I guess that would happen at current limit the voltage drops. – Matt Sep 15 '22 at 22:19
  • Are you basically asking about a solar dump load? – user253751 Sep 15 '22 at 23:58
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    @Matt When your question gets closed, *edit the question to address the close reason*. Deleting a question and asking it again is *not allowed* on this site. A closed question can be reopened if its problems are addressed. – Hearth Sep 16 '22 at 00:42
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    Question is not clear at all to me. I read it several times. This is just some feedback to the OP. It is possible that this lack of clarity is causing some people (not me) to vote to close. I think the question could be made MUCH more clear by adding a block diagram of all the system components. – user57037 Sep 16 '22 at 04:55
  • A supply cannot simultaneously maintain a 54 V output along with a 20 A current limit. If the load attempts to consume more than 20 A, what is the supply supposed to do? Transition into current limited 20 A mode? This violates the constraint of maintaining a 54 V output. 20 A is just an example picked at random since you said the actual limit might be anywhere between 0 and 35 Amps. – user57037 Sep 16 '22 at 05:00
  • I'll work that into the question - when the 54v drops the battery will stop charging. – Matt Sep 16 '22 at 05:45
  • The lithium battery packs I'm familiar with are charged by setting a voltage corresponding to full charge, and then charged with constant current until the voltage approaches the set voltage, and current drops to near zero. – PStechPaul Sep 16 '22 at 07:28
  • As I understand it, an energy sink battery must be maintained at perhaps 50% SOC until it's needed to absorb excess production. One article: https://www.governing.com/now/batteries-will-store-and-send-excess-power-to-maine-households.html. More technical: https://electrical-engineering-portal.com/download-center/books-and-guides/electricity-generation-t-d/battery-energy-storage-systems – PStechPaul Sep 16 '22 at 07:41
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    Drive-by comment (I didn't vote on the closure or the question) - I'm inclined to agree with the closure, because the question is still not actually clear. To get an answer more effectively, *help us help you* by making your actual spec clear and unambigous, without needing to guess at unspecified assumptions and design decisions you've already made. – nanofarad Sep 17 '22 at 03:14
  • OK - it isn't clear to me what is not understandable. Can you please be more clear on what requires clarification ? – Matt Sep 17 '22 at 03:46
  • @Matt It's not clear to me. I'd like to know as much as possible about the solar panel system and your location and it's ability (or lack thereof) to track the sun and the behavior of its maximum power point over differing irradiance values and your location and measured values of irradiance over the cycle of a year. And that's just the solar panel. Then there is this fancy battery that has protection for over and under voltage and upper current limit. What are those details and, of course, why in the heck you think it is of no concern of ours? Look at how few words you've written. No charts. – jonk Sep 18 '22 at 09:35
  • The power management system hardware and software is available here : https://github.com/flatmax/BatteryController.electronics https://github.com/flatmax/BatteryController – Matt Sep 18 '22 at 10:30
  • The system outputs the measurement of production and consumption, that side is pre-determined. Everyone's production and consumption figures will be different. – Matt Sep 18 '22 at 10:31

1 Answers1

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There are several ways to do this: One would be to find a DC DC controller with a current limiting pin that is settable by a resistor, then use a digipot to set the current limit.

Another way would be to find a DC DC controller that has both voltage and current control. Usually these have voltage inputs that could be controlled with a DAC.

Vicor has some isolated supplies that have trim that can be used for current limiting

Here are some other ideas:
Digital control CC/CV boost DCDC chip/module?

Precision circuit that is CC and CV circuit or power supply

Voltage Spike
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