Connect with us

Transformer/buck Converter/capacitor Circuit Question

Discussion in 'General Electronics Discussion' started by Big Dawg, Jan 21, 2017.

Scroll to continue with content
  1. Big Dawg

    Big Dawg

    5
    0
    Jan 21, 2017
    I have a 110 volt flux core welder that has a wire feed motor issue.
    As the welder is being used some of the main transformers power that goes to the wire feed motor lags causing the wire feed not to run at a consistent pace.
    I was told that if I introduce a 25 volt transformer wired to a buck converter with a capacitor would help smooth out the voltage and would solve that issue.
    The wire feed motor needs to run at the same speed all the time when on, unfortunately the power going to this motor can fluctuate (line voltage sags) from time to time.
    Anyone have an idea how to wire this up?
    For example, does the buck converter get wired to the primary side of the transformer or the secondary side? How does the capacitor get wired into this configuration…etc…etc.
    A simple diagram showing the transformer, motor, buck converter and capacitor properly wired to the motor would be extremely helpful.
     
  2. davenn

    davenn Moderator

    13,865
    1,956
    Sep 5, 2009
    that may work if it is a DC motor, but you haven't confirmed the type of motor
     
  3. Big Dawg

    Big Dawg

    5
    0
    Jan 21, 2017
    davenn:
    Sorry I forgot to mention that the motor is 24vdc.
     
  4. Bluejets

    Bluejets

    4,982
    1,045
    Oct 5, 2014
    Usually those wire feeder motors are fairly well speed regulated.
    Are you certain you don't have motor problems?
    Depends on the type/brand/original cost of the welder, the motor is usually just a simple dc permanent magnet motor, not necessarily high quality.

    Another source of irregular speed is in the feeder cable outer core which gets dirty (or damaged....bent?) and loads the drive.

    Also check the drive rollers to ensure smooth operation.
     
    davenn likes this.
  5. Big Dawg

    Big Dawg

    5
    0
    Jan 21, 2017
    Bluejets
    Thanks for the help, however, it is definitely the power lag and not the feed mechanism or the motor. This welder is notorious for this problem. Others have solved it by adding a 25 volt transformer and re-routing the power to the motor through the new transformer, but the consensus was that since the new transformer is still getting its power from the main transformer, there will still be a small amount of lag to deal with...thus the buck converter/capacitor addition. While welding, it's best to have a constant wire feed rate rather then the wire stopping and starting or slowing down and speeding back up.
    I know how to set up the new transformer to take advantage of the welders power and still operate the motor when the trigger is pulled on the welding torch, I just can't figure out how to add the buck converter and capacitor into the mix to further smooth out the power lag. Hopefully someone can provide me a simple diagram or steps of what to attach to where.
    Thanks
     
    Last edited: Jan 22, 2017
  6. davenn

    davenn Moderator

    13,865
    1,956
    Sep 5, 2009
    we would need to see a diagram of the existing feeder motor controller so that something could be designed
    that could be incorporated into the existing circuit
     
  7. Bluejets

    Bluejets

    4,982
    1,045
    Oct 5, 2014
    You could even go higher and regulate it back from there.
    Diagram will be your best start point though.

    EDIT...sorry...having spaz attack...ac high enough for regulator headroom.
     
    Last edited: Jan 22, 2017
  8. Big Dawg

    Big Dawg

    5
    0
    Jan 21, 2017
    Thanks for the help.
    Attached is a diagram showing the wire feed motor, the addition of the new 24volt transformer and how the wiring is modified.
    Looking at the diagram, where would the buck converter and capacitor be placed?

    upload_2017-1-23_16-18-9.png

    Big Dawg

    [Mod Note: added image to thread]
     
    Last edited by a moderator: Jan 23, 2017
  9. Bluejets

    Bluejets

    4,982
    1,045
    Oct 5, 2014
    Block diagram is ok for basic idea but the request was for the actual schematics of the original.

    Neutral conductor of mains should never be switched (big no, no)

    In any case I would tend to enable the tranny and the control board at power-up ( whatever it contains) and
    do your switching of the motor on the output of this board via an auxiliary on the trigger relay.

    Did a quick Google on these particular welders.....seems not a lot of good words are said about them.
    Apart for being el-cheapo ( I imagine it is the same item):eek:
    Appears many are doing DC conversions on the weld outputs for some reason or other.
     
  10. Big Dawg

    Big Dawg

    5
    0
    Jan 21, 2017
    Bluejets:
    You said "Neutral conductor of mains should never be switched (big no, no)".
    My bad, I didn't label the diagram but the "hot" side of the line voltage is going to the trigger relay and the neutral is going to the 24v transformer. I assume knowing this takes your advice from a "big no, no" to "yep that works".
    As far as an actual schematics, I have attached the schematic but it seemed to me to be inadequate thus the diagram.
    And yes, this is an inexpensive welder, that uses AC instead of DC. AC will work, but it tends to blow off any of the protective slag that is needed to create a good weld as it is welding. Changing over to DC will create far better and stronger welds. So the conversions you are seeing online (I've done this) actually takes this inexpensive welder and makes it perform as well as those costing much more. Obviously...no modifications to an inexpensive welder will make it perform like a $1,000 Miller or Lincoln, but for the DIYer these mods can greatly improve the welder for around the home projects. For those of you who know about welders, please note...I would never use this welder for mission critical structural welding.
    I'm still wondering if I should add the Buck Converter to the output (secondary side) of the transformer or to the output coming from the circuit board going to the motor, in order to maintain the same 24volts voltage going to the motor when the welder is under load.
    In any regards, thanks for providing feedback. I appreciate the help.
     

    Attached Files:

  11. DonaldE

    DonaldE

    3
    0
    May 5, 2017
    One of the best forum i have came across, the admins and the other senior members are very helpful and gives detail replies always. Thanks for the info you guys provide here.
     
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.
Electronics Point Logo
Continue to site
Quote of the day

-