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Universal Power Supply with CAN interface
  • Vote Up0Vote Down
    saxin
     
    October 2011
    Access to power is essential, and any application beyond mainstream consumer demand in bound to be very expensive. Therefore a good open source power conversion unit is likely to be competitive on the market and helpful in a new economy.

    Using the white board sketch of a UPS topology I drew the attached. It features CAN since i have an automotive leaning and wish for something apt for automation, but that is not really important.

    Comments are welcome.
     
    Attachments
    UPS_CAN_layout.pdf 23K
  • 16 Comments sorted by
  • A good start.  I guess now you come up with schematics and specs for each block?
     
  • Vote Up0Vote Down
    mjnmjn
     
    October 2011
    I love the modularity of your proposed system.  It gives it flexibility to change or simplify things.  It may be that some of these boards already exist in the Open Source world, since power conversion is common (AC to DC, for example).

    - Mark
     
  • Vote Up0Vote Down
    saxin
     
    October 2011
    Does anyone have experience using this type of equipment? Is there anything important from a functional aspect?

    What is it worth to have the AC output gridable?

    What maximum output do you suggest for the different stages? (What do you use?)
     
  • I have used power supplies many times, though this one includes four different devices or so in one.  Functionally, you really want idiot plugs for connecting to it - so you get the polarity and voltage correct without having to understand it all.

    By gridable I can only speculate you mean that it can operate as a grid tie inverter?
     
  • Vote Up0Vote Down
    saxin
     
    October 2011
    >By gridable I can only speculate you mean that it can operate as a grid tie inverter?

    Yes, that is correct.
     
  • That would be the reason for the component 'wave control', or does that do somethign else?
     
  • Vote Up0Vote Down
    saxin
     
    October 2011
    Yes, I read that grid tie inverters often use microcomputers to sync with the grid wave, and since the AT90CAN in this sketch has a maximum clock frequency of 16MHz I think it would be fairly easy sample and predict within the one degree error allowed, even if sample frequency is much lower.

    The grid tie feature opens for the device to generate income when not in other use, but I still don't know what impact it will have of the material cost. The clock cycles it would claim would likely be spent sleeping otherwise since no other function really requires an MCU (except communication).
     
  • Vote Up0Vote Down
    saxin
     
    October 2011
    On the topic of universality; as DavidIAm mentioned, this device combines four or more devices in one. That will undoubtedly make it more expensive to produce than each of those devices by itself, but much cheaper than those devices together. The casing alone would be a significant saving, then the PCBs, powerbridges, transistors.

    Do you agree, or am I missing something?
     
  • So I'm trying to visualize how to hybrid that.

    You'd have a 'power input' 12V DC (like a solar array) and a 'storage input' 12V DC (like a battery bank), as well as a 'Inverter Out' and 'Grid out' separate 120V connectors.

    DC power input would be used for loads first, then to battery (unless its charged), then to grid tie inversion.

    DC power storage would be used for loads, but never grid tie inversion.

    The grid tie port would automatically isolate/disconnect when grid power does not have any voltage on the line.  

    The Inverter ports would not shut down merely because grid power doesn't have any voltage on the line.

    So far the external box has two sets of DC, a socket to tie to grid, and one or more sockets to provide 120V power to.

    Do we know what kind of power this device is supposed to be capable of in terms of wattage?
     
  • Its worth discussing 'how is this power supply going to be used'.  How many instances would be expected in my house for instance?

    One as a power manager, one as my computer's power supply, one over there where I have a bunch of DC devices hooked up like my cell phone charger and internet router? 

    One I could believe could replace four functions at a discount... but if I need 10 of them on my farm, none of which utilize all four functions one uses 3 and the others use 1 or 2, is it really cheaper?  

    Is there also the way to gang or stack them together in coordination so that they can work together to handle larger loads than any single one was capable of?  What if I want 480/3phase at 40 amps - can I put three of them together and get that out?  Is it even possible with this class of componentry to process that much power even briefly?



     
  • Vote Up0Vote Down
    dorkmodorkmo
     
    October 2011
    could the same system used to sync to a grid wave be used so that three boxes could make three phase power?
     
  • Vote Up0Vote Down
    saxin
     
    October 2011
    First to the functional aspect. In my vision, you only have one or two of these at your farm. It serves to provide AC from a power source such as solar or wind, but could also use a battery source to provide AC or even high voltage DC for various processing purposes. Switching between these should probably be handled by external circuitry, or the device would also need a battery charge circuit which really seems like stretching feature wise. That being said, you could set it to AC input and 14 volt DC output, and charge your tractor batteries.

    As for in- and out-voltages, I plan to use an active PFC stage which should enable the conversion between very wide voltage ranges. Because of that, there should be no need for more than one input and output for AC and DC each (DC-in, AC-in, DC-out, AC-out). That also means the AC-in can take a Japanese 100VAC right to European 240VAC, as well as 50 or 60 Hz.

    In terms of wattage, I can't say where the bottlenecks will be at this stage. I don't know enough about power circuits. It is probably hugely about heat dissipation in the inverter stage as well as the second rectifier when delivering low voltages.

    Slightly off topic - last couple of days I've been thinking about ways to make water cooling safe.
     
  • Vote Up0Vote Down
    saxin
     
    October 2011
    The idea of using two or more devices in parallel is very attractive. The wave control solution should be designed to enable multiple-phase setups. Possibly enabled by a communication bus.

    [Removed confused calculations.]
     
  • Vote Up0Vote Down
    saxin
     
    October 2011
    This project needs several good use cases in order to develop on a system level. If you want to help out, please specify what you would use a universal power supply for, including information such as usage environment, voltages, current or power, how much you would agree to pay for such a device (retail or material costs), etc.
     
  • Vote Up0Vote Down
    dorkmodorkmo
     
    October 2011
    do we have any idea what the input for the induction furnace will be?
     
  • I suggest a keyed shaft, our most energetic way to deliver power is through a rotating shaft.  (this means the induction furnace would have its own torque to magnetic force inside of it, which is an interesting idea, to me at least)
     

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