Connect with us

Help needed with High Current Voltage Regulator Circuit.

Discussion in 'General Electronics Discussion' started by Rob Gale, Apr 21, 2015.

Scroll to continue with content
  1. Rob Gale

    Rob Gale

    6
    0
    Apr 21, 2015
    If anyone can help me to put together a voltage regulator circuit using the following two components I would be very grateful indeed. If you know of suitable alternatives if these are not appropriate, then I would also be grateful. I am attaching the Data Sheets for the two components I already have, and a simple circuit diagram that I am hoping to follow. Although I need some help with the other component values.

    The purpose of the circuit is to control the initial voltage when an inverter is automaticaly connected to a 36v battery that has been on charge. Usualy the battery is at around 44v float level when connected to the charger. Unfortunately it is not possible to place any kind of time delay in situ because the inverter is operating as a UPS and may need to switch over to battery within a few milisecconds. However the inverter cannot handle voltages above 41vdc and will shut itself down. As soon as the inverter is conected and drawing current, within 10 secconds the voltage will have dropped back down to a typical 37-38v for a fully charged battery.

    So far I have:

    100A NPN Power Transistor
    1N3327B Zener Diode

    If anyone can help with the small circuit diagram attached, and values for the other components that would be great. Or if you have any other suggestions which are not too difficult to build with basic electronics equipment, that would also be great !.
     

    Attached Files:

  2. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
    Hi Rob, welcome to EP. What is the maximum current you will be drawing from the battery? What is the lower limit for input voltage for the inverter? It may be as easy as a string of series connected power diodes. I am guessing at these large currents you are not after a regulator really but just a voltage drop circuit.
    Thanks
    Adam
     
  3. Rob Gale

    Rob Gale

    6
    0
    Apr 21, 2015
    Yes, your rignt about the voltage drop..... I had already considerd a bank of Diodes and though I had hit the jackpot with some realy awesome 39v 50A versions I found. But then when I tried to place an order for three of them, I was told they were no longer available !!... 10A now seems to be the largest I can find and I realy dont want to be botherd with fitting a brace of 10-15 of those !. Another issue which has been eating away at me, is what happens to the supply to the inverter, when it falls below the zener voltage ?. Will it suddently shut off with no power at all, or will the zener continue to allow current to pass even if its voltage is below the 39v zener value ?.

    Its difficult to calculate the exact current draw as it depends upon the loads applied which will vary. However it could peak for short periods at 97A and I realise this is close to the limit of the Transistor, but I couldent find a bigger one. Unless I went to an IGBT Transistor and I dont know anything about those or how to connect them up. They seem to have a lot of extra connections on them.

    The lower limit of the inverter is around 28v, so pretty low !. Typicaly I have the automatic disconnect set to around 34v under load as I dont want the battery to discharge more than about 50%.

    My latest idea is to buy some cheapo chinese 3A regulator of Ebay with a max 50v input and a 40v output and use that to control the base of the Transistor. What do you think of that idea ?.

    Rob
     
  4. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
  5. Rob Gale

    Rob Gale

    6
    0
    Apr 21, 2015

    I dont understand what I am supposed to do with this device ?.

    I am happy with the MJ10048 Power Darlington Transistor, I just want to know if it is compatable with a 1N3327B Zener to control its base ?. Also if the supply voltage falls below the 39v, but not below 32v "thats not a problem at all". I just need to make sure it never goes above 41v !.
     
    Last edited: Apr 22, 2015
  6. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
    Hi Rob
    This is an alternative to your regulator if you wanted another option. You said you had considered diodes but could only find a 10 Amp version.
    The regulator design you have chosen will only regulate to a point which will be when the input falls below the zener threshold. It will actually be a bit before this because the zener need a certain amount of current passing through it to regulate. As the voltage falls the output voltage will follow this and as it rises the voltage will again follow this until the zener diode stops any further rise on the base of the transistor.
    Thanks
    Adam
     
  7. Rob Gale

    Rob Gale

    6
    0
    Apr 21, 2015

    Hello like said, its not meant to be a voltage regulator, its a voltage limiter. So I realy dont care what it does below 41v. The single sole purpose of this circuit. Is to prevent the voltage rising above 41v which is the maximum input value for my inverter. However if the voltage falls below 39v and its stops regulating, no problem at all !. As long as the transistor doesnt turn off and cut the power, its all good !.

    Ohh and also I have no trouble locating high power Diodes. It specificaly Zener Diodes of 39v and above 10A that I'm struggling to locate.

    Rob
     
  8. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
    Yes the regulator idea is a good one because just looking at the data sheet for the transistor it looks like you are going to need at least 1 Amp of base current for 100 Amps output.
    Thanks
    Adam
     
  9. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
    No it won't turn off.
    thanks
    Adam
     
  10. Rob Gale

    Rob Gale

    6
    0
    Apr 21, 2015
    However I am now back with the 10A Zener again, because I discoverd the regulator will only output an amount which is 3v below the supply. This is a big problem.... because I dont have that much room to play with. Also 100A at 3v PD is 300w of heat to dissipate. So I want to keep the limit voltage as high as I can to the 41v ceiling.
     
  11. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
    He is something that might work. Don't worry about the transistor looking a bit different I have added the correct parameters to simulate yours. It stops regulating at approx. 41 Volts.
    Adam

    100A.PNG
     
  12. Rob Gale

    Rob Gale

    6
    0
    Apr 21, 2015

    That looks interesting !... I will certainly bear that in mind if my existing circuit doesnt work out.

    However as I have already bought and paid for the large Transistor and Zener now at some cost, I ought to give it a chance. Refering back to the diagram I first attached to this thread. I think I will use a 100w 4Ohm resistor for R1. But im still not sure what value capacitor to use for C1. I think I have a 4700uF in the drawer, I I might try that ?..... Perhaps you could let me know if thats a reasonable size cap to use in my circuit ?.
     
  13. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
    Hi Rob
    This is your circuit! I simulated it for you showing you it should work. It's a steady state D.C simulation so the capacitor is not important.
    Adam
     
  14. Arouse1973

    Arouse1973 Adam

    5,164
    1,087
    Dec 18, 2013
    The capacitor value will depend on the type of load transients you get. You could try the capacitor you have and see if it works, as you already have it.
    Adam
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Similar Threads
There are no similar threads yet.
Loading...
Electronics Point Logo
Continue to site
Quote of the day

-