Electronics > Projects, Designs, and Technical Stuff
Very wide range input power supply
Marco:
Personally I'd just drop the voltage to 140 and then use an off the shelf mains fed high power balance charger. Do you really want to rely on battery protection circuits while charging at 30A?
This allows you to work all the way down to 140 volt, just need to design a non isolated high power step down converter.
PS. well I guess the balance charger should have some kind of programming input so you can drop the charging current or restart it when the power drops out.
NiHaoMike:
Some BMS boards, most notably ones designed to allow a LiFePO4 pack to be used as a drop in replacement for lead acid, are in fact designed such that the charger can be a simple CVCC type.
jbb:
--- Quote from: NiHaoMike on April 13, 2020, 01:40:34 pm ---A string of solar panels, the 520V figure is the design max of the main inverter module...
--- End quote ---
...hang on. These batteries you want to charge... are they used to feed an inverter in this solar system?
If this is some kind of grid tie + battery situation, how much control do you have? There might be interesting ways to address the whole problem (e.g. panels connected to DC link via boost MPPT. DC link range would be somewhat constrained (e.g. 400 - 520V) and reduce voltage span requirement for auxiliary converter. Auxiliary converter could be bidirectional to support both charging and discharging modes.
NiHaoMike:
--- Quote from: jbb on April 14, 2020, 12:32:22 am ---...hang on. These batteries you want to charge... are they used to feed an inverter in this solar system?
If this is some kind of grid tie + battery situation, how much control do you have? There might be interesting ways to address the whole problem (e.g. panels connected to DC link via boost MPPT. DC link range would be somewhat constrained (e.g. 400 - 520V) and reduce voltage span requirement for auxiliary converter. Auxiliary converter could be bidirectional to support both charging and discharging modes.
--- End quote ---
System architecture is solar panels supplying the main bus that can go up to 520V with no load current (could do per string or per panel MPPT later on but planning to just have blocking diodes at first), on that bus there's a high voltage DC/DC converter to interface with a high voltage battery (that is optional), as well as an inverter for a 3 phase compressor motor, another inverter for grid tie, and yet another inverter for backup. Basically, I'm repurposing a cheap Prius inverter module into something similar to a Sol-Ark inverter (in particular, the zero export feature that supports external sensors), but at 1/10th the cost after including all the other parts needed to build the complete inverter.
I can't just power the auxiliary supply from the high voltage battery interface since (without the high voltage battery) there would be nothing to get the DC/DC started in the first place without an auxiliary supply. I could bootstrap the whole system from the low voltage battery but I would prefer to design it so that failure of that battery would not make the system unable to start.
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