RF Man discusses load sharing in parallel power supply's and boost converters
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- Опубликовано: 18 сен 2024
- Two techniques are demonstrated to resolve load sharing problems that occur when using D.C. Power Supplies in parallel. If you are interested in purchasing one of my LDMOS amplifiers, you may contact me at 770-500-5945 or checkout my website at: RFlinear-amplifiers.com
Solution to 6 month of wondering ... Cool!
Many thanks from the Kaiser.
Yes many thanks from me as well. I have searched the internet and other related books to no avail. Finally a solution to my load sharing problem. I will now attempt this method in the next few weeks. Thanks again RF man
Oocheewawa my eyes are burning (240p)! Thanks for your effort!
Thanks for the tip RF Man. I just purchased 10 each .05 Ohm, 50 watt resistors. I'm going to parallel 5 of them for each supply thus giving me a .01 Ohm 250 watt set up. I only need to plan for 123 watts at .01 ohms so I should be good. Can't wait to get started on this project. v/r and 73s
nice! dont forget that diodes are not needed since there are diodes in the boost converters circuit, they waste alot more power than the resistors, 0.5v * 8.3A = 4.3W not counting resistance also. cool video thanks for sharing!
Correct and they dropped the voltage by 0.5 volt
Great example of equalizing resistors. Truthfully, I always doubted they did much but included them in every supply I built out of obedience/rote learning, Your demonstration fixed that.
You could not have demonstrated that any better. Awesome demonstration! It definitely brings some ideas to my mind on improving some future circuitry and adding extra safety measures when I am putting together power suppy modules and making sure they are 100% current sharing the way they should be. After running some tests this may even cancel having to make the power wires equal length sometimes adding extra obstacles when working in tight spaces.
You could have not explained the material better. Gave me some ideas and refreshed the theory. Thank you
Thanks for your comments!
Dude thanks for pointing this out ive duplicated it with 2 of the 20 amp models for solar charging its doing just fine
Thanks for the feedback....
oh hey there... :D
i am about to do similar. thankyou. tangent. is it possible to series these or similar cheap switched power supplies?
ans3rina3 you can series them, just make sure you have reverse polarity diodes, they should be reverse biased across each PSU in series, the issue is since these are not isolated PSU's the inputs need to be isolated, otherwise you have a grounding problem and it will short, I made a video building a PSU using 8 laptop chargers it is 3 different outputs, leftmost is 2Series 2Parallel, middle and right is 2S1P you can see how to connect the diodes across the positive and negative of each PSU in series : ruclips.net/video/lw_bY6FEVEs/видео.html
SuperBrainAK thankyou! rf man do a video for us sheeple please :D
Thanks for posting, it's just what I was looking for.
Thank you man!
I will be using those boards gor my custom e-bike, I just hope ur calculations are correct 😅
I've noticed that there are exactly two types of these, 1200W and 1500W respectively. Although some are being sold as 1800W 🤔
I'll be using 2 car batteries in series, which will be around 24V, boosted to 48V (or more) depending on the motor, since it's "rated" for 500W - wish me luck!
Did it work? I'm actually gonna try to use two of those 1800w dc-dc converters for 1200w e-scooter. Problem is, converter max voltage on input is 60V. And my battery is 67V when fully charged. What I want is to keep the voltage to scooter at around 65v so I have max speed even when voltage on battery drops to 45V (empty but still safe voltage). Hopefully this works on the input as well (battery out to two dc-dc converters in parallel) and then to the scooter.
@@KolyaNadj I found a different solution. So I actually didn't even try this method. What I can say for sure is that you won't ever get the full power out if these things, no matter the conversion ratio, so keep that in mind. It's about half the specified wattage. Good luck!
@@ShaaRhee Thanks for the heads up. Hopefully 2 converters will be enough.
RFMan, thanks for taking the time to make this video! 73 from your Upstate NY paisan.
OH MY GOD! THANK YOU! What I am now trying to do is: use two 1200W boost converters (very similar to yours) in parallel, to move 'extra' energy from solar panels when their 12v battery is full, to 48v battery used with a more powerful inverter. The setup will work every day, so I want to have considerable redundancy both in terms of power handling capacity and reliability (I am from Ukraine and I think we might have some issues with electricity supply again in winter). And I went through quite a few videos on 'paralleling' dc power sources. Yours is a savior, others did not really address the possible solutions to the issue when one power source takes all the load. Can you please tell me, where there is a lower energy loss, when using resistors or when using diodes? If I understand correctly with resistors I need to have them in series with the actual load, separately for each converter, and to pick their wattage as low as possible with the voltage used (55V in my case for max 48v battery charge) to have minimum current drop. The planned power for the converters is 400W total (200W on each converter) so I hope I will not get to much heating on converters this way. Also there will be a separate charge controller, that would connect the boost converter's input to 12v battery only between it's 90% to 100% state of charge (having converter's inputs connected to 12V battery the time and actually connecting their output through charge controller relay sounds better in terms of smaller current on the relay, but I am a bit worried about converters sitting with no load connected to battery all the time). And maybe you could advise a better approach to my 'understandably overkill' solution. Thank you.
this is very informative RFMAN! Thanks! pls produce more videos!
led light is an amazing replacement for the resistors and give me super savings whar charging supercars, the efficiency is top of the charts. the plus to plus connection represents the future of using energy. it's a game I been playing and innovating for the past 3 years.. I also devise a dual buck converter set up relooping the volts to the source with success, but one error cost me a step up.... pouf... balance can be attained... I used a hade made capacitor to reloop the higher voltage back to the lower source... .p.s the magnetical field create in transferring hi amps is a potential extra to be used... my choke coil is very powerful...
Thank you for making this.
You can use 100V 50A TO220 pkg, dual diodes (in parallel) mounted on a heat sink. I have 10x1200 W SMPS in parallel. Works great. I have only ever loaded it to. 800 amps.
Do you have a partnumber for those dual diodes? What voltage and amps is 1 smps?
Finally a solution to my load sharing problem.
You have 2x 1800W step up's in parallel so over 3000W available at 50V but how much of that power can you pull through hose resistors?
saved my day, thanks!!!
Glad I watched till the end, or I wouldn't know diodes can also be used. Way better approach for my setup.
Could you use a current mirror made from discrete transistors to join the converters together instead of the resistors/diodes? I would think it might be useful at extremely high currents (like joining multiple buck converters in parallel.) I saw it discussed on the electrical engineering stack exchange but they were not sure if it could work.
Great video! Always clear with the explanations!
At 7:35 you point to an adjustment, but that happens to be for current limit, not voltage
THANK YOU VERRY MUCH. Answered a long standing question
240p... did you record this with a potato?
Would you guys kindly leave the poor, innocent potato cams alone? I'm on 5mbps/768kbps ADSL smoke signals here in rural OR and 240-480p is my usual rez. Wish I had OC3, but...it still beats the 1200baud modem I started on.
@@ljprep6250 Shout Out to everyone that had to live with a screaming modem!
@@charlesrichards5389 Yup. We learned to speak modem so we could tell if they were connecting properly or not, too.
What if you have two CC-CV boost converters and you simply set each one to limit the current to half of what you need? Say you need 10 amps at 50V. Set each one to 50V and 5A. Would that work?
Very interesting video, thanks. If I may ask a question. I have a MeanWell power supply (CC,CV) and a battery hooked in parallel then again in parallel with a load. Im thinking the battery would delivery the brunt of the current to the load with the power supply mostly charging. At least thats my preference, with power supply delivering current to the load if it demanded more than battery capability.
is it posit is possible to build a buck converter-based dual bench power supply with a master-slave tracking system for series and parallel operation.
Thanks for the information I learned a lot 😊 take care! 73 de ve3hip in welland Ontario Canada 🇨🇦
Sir, can I limit the output current of each boost converter to a certain amp, lets say I set each of their current limit to 10amps, and if the load draws 10amps, the first boost converter will do all the work, but when it draws 15amps, the second converter will kick in to contribute to the load sharing, and use shottky MBR60100 in each converters output to isolate them, this way with the shottky diodes the voltage drop is minimal compare to that of the resistor. This set up uses the second converter as a back up if the first one reach its current limit, this way Im not pushing the first conv. to its limits. Am I making sense?
I’m using a 36 volt 460 watt hour battery out of a broken e-scooter and I need a 13.5 volt output to run my inverter so I want to run 2 300 watt buck converters to an inverter. I didn’t do any calculations though and I bought several 0.1 ohm 100 watt resistors. I’m pretty sure I’ll end up adding more buck converters to run more powerful inverters in the future if I get more batteries. Next to buying a 36 volt to 120 volt inverter this is several times cheaper.
Can you paralleled up the red boost converter without issues? Yes or no. I’m trying to achieve more amp.
I can't find the video talks about noise coming from the step up converter I built a amp using the same step up and on the bench I didn't hear any noise but when I put everything in a Case I'm getting noise from the step up converter can you paste a link to that video thank you
What about resistor AMP rating? The resistor leads don't look rated for 30-40 amps!
I want to power 1000W from a 16V battery.
Greeting! Good video! With which converter could it get 5V and 8-10A so that it can work longer without overheating and shutting down? Thank you
thanks RF man for your demo it was very helpful.
what about .01 ohm? can i use .01 resister rather than .1 or .2 ohm?
I would go for the diodes solution. It's safer to use Diodes. Yes you can use .01 or .02 Ohm but it has to be same rated on each and always calculate the wattage of those resistors or resistors will be burned out.
Nick Chow, yes you can use .01. I plan to do same and will report findings here when complete. Running resistors in parallel will allow you to obtain the ohm you desire, but limit the voltage drop and increase wattage rating. Example five each .05 ohm 50 watt ran in parallel will result in .01 Ohm 250 watts (approx). Your still gonna have to do the math provided in RF Man video to obtain exact wattage rating needed for the power supplies you plan to use. 73s.
@@baltimore_amp_repair how did you go testing the .01ohm resistors? can you report if they work with the demonstrated DC-DC boost converter running them in parallel. Maximum output on the 1800w version is 22amps x 0.1ohm is 2.2 voltage drop, this is 48.4W dissipated on the resistor!, A .01ohm resistor will dissipate a 10th of that wattage being 4.84w. so the power saving is a big difference.
Hi, thnx for sharing this. The input of the DC-DC converters can be connected direclty to the same PS or similarly to the output, resistors should be added ?
How do you determine the load resistance? Doesn't it vary?
Quite interesting. Thanks for sharing.
How do you calculate the diode amp rating needed? I am powering a 24v 12a motor. I have one PS of 24v 9a, thinking of getting another one of the same 24v 9a, or just 24v 6a (cause it's half the price) for a total of 24v 15a in parallel. However, the back current from the motor, if I am not wrong, could send current back into the PS, so the diode may be better in this case. But how do I calculate how much amps the diodes should be rated for? Also, any problem connecting in parallel the 9a and 6a if they are not the same amperage?
Is it possible to use the diode instead of 0.1resistor
so this is how i power a 48volt 20amp max draw ebike motor ? i mean i am trying to avoid spending 500-600 dollars on a 18650 series battery pack with BMS and charger.... the application is for a tricycle so weight isnt that much of an issue but i would like to try and reduce my number of 12volt batteries required. each battery is 12volts 18 amp hours.. but they weigh 13 pounds each....could you help me with this ? do i need 2 batteries ? 3 batteries ran in a series ? or should i just buy 4 batteries and be done with it ?
i am an old roofer..i am good with a hammer...my electrical experience is basically "plug-n-play"
Bob Americana, check out super capacitors. they are extremely light and pack a lot of power but expensive. Also Harley Davidson now sells lithiom Ion batteries that are 12 volt and super light and also have lots of juice. again expensive. v/r 73s
Dear RF man, can you help me, I have a 72v ebike with a BMS that has passive battery cell balancing (syphons the cells via a FET). I have made a booster pack out of 2 separate batteries for the bike, one is 11.1v nominal 3s and the other is 36v nominal 10s li-ion. I have them on separate circuits with appropriate breakers leading to the same step up converter you are using. I have set it to the appropriate max battery voltage of my bike on the output end so it charges. However when it charges, it seems to send the balancing function of my main battery BMS into a fit, the cells fluctuate up to 4.5 volts and down to 3 volts, this trips the protection of the BMS circuit and cuts the charge input stopping the charge. If I turn of balancing it is fine.
My question is, do these step up modules put out lots of noise that could effect the functioning of the FET on the 72v battery BMS?? I am trying to fix this problem so I can maintain balancing function whilst charging from the boost module. It charges fine off the mains charger which also uses a step up, but only difference is, it has a 48v 2.4kw rectifier on the input end instead of a battery.
Hello. I have problem. I tried to connect two boosters (250W) parallel but they both burn out. Even tho the were not under the load. Now I would need to connect another two boosters (1800W) but Im afraid to do it. Any ideas why frists did burn?
Also I have another question. I have motor 24V and it takes 90A while starting. Is there any device where I could set max load 50A so motor couldnt take more?
Sorry so can i parallel 2 step up module from the same power supply? I want to get more current
Those 12v smps connected in parallel, if connected with a pwm to charge a battery, is there any need to do the power sharing thing?
know this is a bit dated but had a question that having a hard time getting an answer. Trying to figure out result of circuit similar to this except I have inputs (AC current) of the switching power supplies(dc battery charging) wired in series. flow of power would be AC current to 2 supplies in series which have dc outputs wired in parallel to battery. seems to be working fine but just wondering if there's potential dangers doing it this way
Its ok a parallel wiht that boost converter...thank uou
What resistor voltage drop do you suggest designing for? I see you used 0.83v, of course, but have no idea of the ideal value. Thanks...
What about really low voltages like stringing together cheap LDOs and without as much heat loss for battery applications?
Can you settle the use of diodes in this? And 240p come on? Otherwise solid demo, really helpful.
Hoping for an idea and some help! Love the videos! I need to produce 216v dc and around 35-40 amps or maybe more. My source will be a lithium ion battery pack. Any ideas on heavy duty high voltage boost converter?? Thank you for any help! Wish there was a way to do like you did here only put sets of them in series. I was watching your other videos on paralleling your boost converters.
hello, how low can you go with resistors to balance the circuit? 10mohms ? Thanks
You need to use high wattage resistors. I suggest you calculate the expected power using ohms law (P = E *I). If you place the resistors in parallel you can handle for power.I Hope this helps.
ok so i'm going to try to use 4 like these in parallel to convert from a 60 amp 13.8 V alternator 25.2V this will be to charge a lithium ion battery.
now i was thinking of going for 0.02 ohm resistors
Each boost converter will be set individually to output 25.36 volts with an amp output of 8.2 Amps.
There should be a loss of 8.2 x 0.02 = 0.164 V so that will give the 25.2volt that is the max voltage to charge my battery.
The dissipated power should be (25.2 x 25.2) x 0.02 = 12.7 W
Therefore i'm going for cheap 35w TO220 to be on the safe side.
Else
would a Schottky diode work ? was thinking of using a 20A 40V rated one but there is no power dissipation on it.
Thanks for your time
How can you adjust the Amperage (10 Amps) on the 12 Volt Rail on the PSU, down to 1.35 Amps going through the Booster Converter? I only see one Potentiometer and that one's for Voltage.
DC loads will only draw what they need. 10 amps means you can safely run 6 of those with head room
What resistor will I use if the power supply is 20amp each
Any different measure to combine a SMPS with a Linear PSU (in parallel)?
Hi ! Can i use a PC PSU ( 12v - 22 A ) to supply 5 drok buck voltage converters set in parallel so each is a 12 V 4,4 A load ?
You might as well just get a bigger step up module. Like the 1500w or 1800w step up modules in the video. Also if your having each module at 4.4 amps, so all together are trying to put out 22 amps in total, then you will trip your pc power supply as it wont be able to put out the current. Remember that there is an efficiency loss when stepping up electricity, around 20 - 25%% for these things. So it will be pulling closer to 30 amps from your psu.
@RF Man Channel Dont those boost converters already come with 2 double schottky diodes (STPS20S100CT) on the output stage? Albeit they are before the capacitors...Do we still need to load balance?
Yes, you still need to balance the load.
@@rfmanchannel6915 same way with resistors or will it work with schottky barrier diodes?
@@RandomPsychic You can use diodes as well. The approaches work fine.
Can anyone tell me if this applies to step down (buck) converters as well?
Hi, can I series the output Boost Converter to increase the Voltage??,,
Because, when I tried it did not work (Boost Converter Cut Off)
Actually, I tried the same methode on SMPS power suppy it Works..
Please help me...
Hey, what resistors would i need for 4 30A 12V Power supplies?
Jacob, .1 Ohm 100 watt resistors coming off each supply positive lead should do it but, you will have a voltage drop of 3 volts. If you go with .01 Ohm, 10 watt resistor it which will keep your voltage drop to .3 volts. I always double my wattage rating and would purchase .01 Ohm, 20 watt. Good Luck and 73's
yeah rock n roll bro, well done. it's like looking in the mirror but with gear. lol grrr emf...pouf...lol in my case. lol
WoW...perfect..
Dear sir can I connect buck converter DC to DC
How would a 0.1 Ohm resistor add anything a long wire would otherwise not add? I don't understand how adding such resistors would isolate anything compare to the case without them as wires themselves have some low level resistance.
I found (this)[ www.ti.com/lit/an/snva794/snva794.pdf ] to be quite helpful in answering my own question. From my understanding so far, I still think "isolate" may not be the right word to use here?
@@topherbuckley The resistorsa do in fact isolate the regulation loops in each power supply. Thanks
There is no audio on this?
how about series sir?
Need some help from you
Will This work with diodes
Nvm
So I found 100W 0.1ohm resistors on Ebay for $1.34 apiece.
Just uploaded a video where I demonstrate RF Man’s load sharing technique. ruclips.net/video/vAMLIRKKBp0/видео.html
Thanks RF Man
73s
Are you new yorkian
240p