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- เผยแพร่เมื่อ 30 ก.ย. 2024
- Dave explains the three main methods of Uninterruptible Power Supply design - Offline, Online, and Line Interactive. And then opens an APC 2200XL rack mount UPS to see how well it matches the classic block diagram theory. Will there be any surprises?
Schematic: eevblog.com/fil...
Patent: Method and apparatus for providing battery charging in a backup power system
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How would you disable charging of the battery only?(in case of multiple ups on same battery). Without using diodes in series with the battery.
I got one hooked up to my 3d printer. No more shall power outages waste my material!
Also, a bit of a question: If I have a triac-based power supply for a high power (~400W) device, would those pulses of high current damage the UPS?
P.S. The device would be a heater is for the heated build plate. It really only needs to be UPS-protected for long periods of time because of the thermal mass.
Nice explanation Dave, I really like your videos on DFM.
A quick comment on how the charging work:
Voltage reflecting on the battery side of the transformer (primary side) will never be high enough to charge the battery through the four mosfet body diodes. (battery shouldn't be charged this way because you cannot control the charge current and stop charging appropriately)
In order to charge the battery, the mosfet H-bridge works like a boost converter, boosting the voltage to high enough to charge the battery, and at the same time control the charge current and do PFC (Power factor correction).
In inverter mode, the H-bridge works like a buck converter having output voltage swing at line frequency.
Half-bridges or full bridges are bidirectional converters.
You can easily control the power flow both ways by applying correct PWM. Usually, an algorithm called dq control (similar to field oriented control) is used to control the power flow. For example, when vector q is positive, power flow forward, and when q negative, power flow backward.
This idea is not new, but applying the idea to UPS to simplify the design is really smart.
How the H-bridg work as rectifier
why don't they teach it in college, the topology practical design. When I opened up my 800VA APC UPS, I wonder how there's only one power transformer who's responsible for AVR, charging, and inverter, with only 3 cable for high voltage and 2 cable for low voltage.
But after all these years why don't they switch to high frequency transformers, instead staying with the bulky heavy transformer. I noticed these designs get warm even without load consuming around 20 watt, that amount does affect the energy bill for 400W UPS running 24/7, and all UPS I can find does that except for the DC UPS's.
If you can't understand "STRALIAN" too bad for you. It's about the information not a basic English class lesson.
This is an "extended run" APC UPS as designated by the "XL" suffix on the part number. 2 things make it extended run: 1) the secondary battery input and 2) additional cooling fans.
The extended run models are "highly desirable" for use as straight inverters because on the standards models, the transformers will overheat within about 30 minutes of heavy continuous use.
Of course, now that I told you that the transformer is the "weak link" you can add your own additional cooling including thermal compound between the bottom of the transformer and the case !
Awesome find!
The specs tell you it's a sine wave inverter.
Thought I'd make a correction on you DaveCAD @20:00.The H-bridge in the UPS is all N-channel. The N-channels are connected backwards in place of your P-channels. The reason for using N-channel over P-channel is that N-channels have a lower RDS then there P-channel counterpart.
Usually that's for high voltage isolation. Helps reduce surface leakage and capacitance a bit.
The patent does not expire because the company goes bust. Of course if there is no one left to sue you that does help a lot!
Sure, not ideal engineering, but they are obviously getting away with it, and have done for several decades now.
The video was already long enough. Even if I did that I'd still have people calling me lazy for then not probing the charging waveforms, gate drives, and all kinds of stuff under various loads etc, etc. Give me a break.
Amazing video! Thanks for explaining how each type actually works.
One tiny correction, though: at 6:22, the fact that for a given power, a lower voltage implies a higher current, is not Ohm's law, it's the relation between those three quantities (what we may call the power equation): P = V * I. Ohm's law has nothing to do with that.
I want your 555 timer circuit shirt! Lol. I've read up on this before, but i have to say, i'd much rather watch you explain sometimes.. I'm often told i can bring some things to life which are otherwise boring but you do it so damn well.. You should present how it's made/how it works/other similar programmes because you make everyone else look shit!
Pretty sure it's OK to use the body diode for 50Hz rectification, most mains frequency diodes are pretty crummy in terms of switching/reverse recovery performance. Not sure about the body diode, but (some?most?) MOSFETs have a positive temperature/resistance coefficient, thus they share current pretty well. Series diodes are much more of a pain since you have to get voltage sharing.
As for the large number of caps, that's not unreasonable for single phase -> 100Hz power flow and all...
6:36 but by doing this its working becomes almost same of offline type because it powering the output not by battery but by Mains Rectified DC power ?
It's funny that you said "patent" your way long enough that the probably correct way now sticks out and one immediately wonders "Wait, what was that word?". Patents suck anyway, so who cares? :)
How does this type of UPS deal with a lightning strike?
How do you not know what Best Power is? I mean the company has been split into pieces and sold for quite a while now but that place was such a legacy. It's building is still standing in Necedah, WI being rented out by the original owner. That place is such a damn throwback, my parents met while working there and my great grandmother was one of the first to get an award for exemplary work. I was practically raised there. On the upside, since closing down, my dad has started up his own business based around UPS.
Where can I get a copy of DaveCAD? :D
Raz I believe they sell copies of it at Staples :-P
Pirate it; like everybody else does.
Support is abysmal, anyway.
I was having blackouts and was worried that the sudden power drops may damage my TV. I bought a 115 amp 12 volt solar battery. I connected a really good charger to keep it charged up. I then bought and installed a 400 watt sine wave inverter. I put fuses in for safety. This is all in my garage. My TV and DVD player only draw 105 watts of electricity. I only use the TV for 3 hours per night. The TV power cord is full time connected to the inverter. The inverter is switched on and off via a remote control. This all cost 480 dollars and I have had no worries so far for over 2 years. The power goes down but my TV is safe and just keeps right on going. The thing that you pulled apart is just an expensive wank on as far as I can see. More for rich geeks than us "ordinary folks".
+7316bobe UPSes are very common and useful devices, and although he gave your home PC as an example, they are not often used by consumers. These are mostly used for commercial industrial applications or to provide clean power and graceful shutdown for important equipment. These things can be small bricks for one device or massive units for many. For an individual device you won't see these often in someone's home, but you will see it connected to point of sale systems in stores and banks. Your solution is interesting but not very practical for other implementations, especially since it's a solar battery. It's silly to build something for extra reliability that draws its power from an unreliable source.
And this is why that model UPS is rubbish. It has zero capability to stop charging the battery pack. As a result, it *WILL* eventually incinerate the batteries. I have yet to see one that hasn't. A quality UPS monitors the battery string(s) and stops charging them when they've taken what should be a full charge -- continuously dumping current into a battery is a bad idea.
Yes, this one uses only N channel MOSFET's according to the schematic.
Love the way the bridge is used as a rectifier. 👍🏻
Genius !!!
To get a sine wave output it must run PWM at a higher frequency.
I must catch up on your videos Dave ! Did not know you had this video on UPS! GREAT video !
4:29 how can rectified main dc be bypassed to output without ac conversion ?
I disassembled a large online UPS, and it didn't follow that schematic. It was near identical to your "offline" schematic - the main difference was that the step-up transformer was an SMPS and went before the inverter. The battery voltage was stepped up from 400 volts to 700 V (+/- 350 volts), allowing a simple push-pull topology inverter.
The difference is that in an offline UPS, the load is directly supplied by the mains. If the mains fails, then the transfer relay switches the load to the inverter. In the online UPS, the load is supplied by the inverter, unless the inverter fails, in which case it transfers back to mains.
The common reason for inverter "failure" is actually the output being severely overloaded or shorted (e.g. due to a fault on a single load where a UPS supplies multiple individual loads). In this case, the inverter voltage drops under the overcurrent stress, and the load is transferred to mains with its high current supply capability. This can also happen if regenerative loads are connected to a UPS (e.g. motor drives) and the reverse power exceeds the handling capability of the inverter causing it to trip out due to DC bus overvoltage.
There is usually a difference in the type of switching. Offline UPS systems are designed to be cheap, so tend to use a relay. Online UPS systems are designed to be high end, so the delay of relay switching is unacceptable, so online UPS systems usually use IGBTs to switch between inverter and bypass mode.
The online kind of UPS can be designed without the switching mechanism using a bit of diode magic.
Also known as 'buck' topology.
Please Explain i need to know
I don't know, you tell us. Is there any prior art pre-1991?
31:26 you are right but sightly wrong they used Not h bridge MOSFETs as rectifier instead they used the Body diodes of the MOSFET used in H bridge , as rectifier .
Oh you already mentioned it later here 31:56
I do occasionally mix different pronunciations, like via.
hey dave................... this sivaram. I want to the information of the caps which were connected across the MOSFETS, which are are used in this invert-er. where should i see.
Actually I do believe that they are turning on the mosfets at the same time that the body diode would be on (as stated in the comment you commented on). It would have been a simple enough optimization to figure out, and they would have the control circuitry that would otherwise be dormant. It could also allow them to do some power factor correction to make the charge circuit seem more like a purely resistive load.
You changed your pronunciation of the word "patent", what happened?
dear dave , if you can please show us a repair of a simple 600VA ups. they fail all the time.
i would like to know where can we use a transformer from a 600VA ups , i have 5 of them .
thank you!
Yes, there are many different flavors.
The charge current for the batteries is much lower than the discharge current, so they can get away with it. I would expect the charge current to be a few amperes at most as SLA batteries do not like high charge currents.
Hello Where can you buy such large capacitors because one mine burned out, one die,which can be replaced Rifa PEH534MB14150A3 1500uF 63V
Due to creep creeping around my house with armed robbery on the creature's mind I installed a photobeams alarm system, and a 8 cameras security system monitor outside my house. I bought a "APC UPS Battery Backup and Surge Protector, 600VA Backup Battery Power Supply, BE600M1 Back-UPS with USB Charger Port" to power my PC and security equipment. I have a 12V deep cycle marine battery in my basement with a surge protected 4 amp float charger. I supply 12V DC power to my modem, router, and photo beam alarm system straight from the marine battery at all times. The UPS supplies power to my PC and security camera system. I removed the UPS battery that could only supply backup 12V DC for 16 minutes. and connected the marine battery to the UPS battery connection wires. The marine battery can supply the entire 140 watts my setup draws for 82 hours. . I don't know which of the three categories my APC UPS BE600M1 is in, but I did a test by unplugging the 120V UPS supply from the utility and nothing shutdown. Nothing at all happened. Not even a blink.
Those battery packs absolutely weigh a ton - I have a 6kVA Riello with 192volt batteries - it's heavy with the batteries out but almost 65kg with them in! 32A 240v AC in 2 x16A 240v out online system - it's a beautiful UPS and built like TWO brick shitters! :-)
I have used many, many huge (100kva and up) for data centers. The "U" in UPS means UNINTERRUPTABLE. This means ZERO power transfer time delay and NO PHASE shift. The output power is completely obtained by the inverter. This is what a true UPS does anything else is a STANDBY lower supply.
I had one in a large data center that supplied global credit card processing systems (all mainframe stuff) the UPS room was 625 sq feet. I contained racks of batteries and a unit on the wall that just buzzed. It supplied 3 phase power to the data center. With all thay power we only had 45 min if battery power. We didnt need much because we had a generator that would activate if we lost power so at most the batteries were needed for 2 or 3 min until generator stabilized
One of the things Dave missed in his review of the patent is that all of the diagrams show 3 N-channel MOSFETs. No P-Channel as he showed in DaveCAD (love DaceCAD !).
All EE will know that N-channel MOSFET are less expensive and more reliable then their corresponding P-channel cousin, if the P-channel even exists !
Hi Dave, I have an old APC UPS, that I'm thinking of converting to a 12V DC UPS to power my router. Bypass the inverter part, as I only need 12V DC. Any instructions or links to go about doing this?
I would love your help. My power goes out a lot where I live, so
I have a couple older smaller APC UPS ,[600w and a 400w] that I have had some lights and laptop hooked up to with larger deep cells and they would run a really really long time, dependent on actual battery life.
I bought a APC Back-UPS Pro 1000 S BR1000MS [pure sine wave] to replace a non pure sine wave UPS and put my 100 amp hour battery on it, to run my flat screen TV and some light off grid . But, while the load is well under the max load of this inverter, this UPS unit, thinks it has the same stock 7.5 amp hours batteries that they come with it and only runs for 24 minutes and it thinks it needs to charge the fully charged 100AH battery for 16 hours.
Not expecting this to not work this way I put time into this thing taking out the plastic around the transformer out to put on metal grills and fans because I know it would be getting hot .
This has a cable to my computer for some other options , but nothing to disable this battery timer thing that is posing as a monitor.
It would be great if you investigated this and found software to disable the battery timer shut off.
It does have several relays on the board and i hear it switch off. If I knew which one, I could bypass it with a switch.
Hi Dave
I must disagree. Is deficiently, low capacitance in here for the price of that monster. With that power I will put at least 20.000uf. Dont be paltry, like in your multimeter design ha-ha. Do ir better Dave. More filtering is always better. Also a better high speed ADC´s, less quantization noise, etc. Btw that costly design doesn´t convice me at all !!. I would expect more, a toroidal transformer, dual stages, multi regulated power supplies, temperature controlled pwm fans, well you know... knockoff - It´s plainly a naaaa...
I have an APC Smart UPS 750 which I modified a bit to use a pair of large external deep cycle batteries (24V 115AH) in addition to the internal "main" battery (24V 7.5AH). It's rated 500W 750VA but I de-rate that to 200W max (100W normal load) at a 0.6 to 0.8 power factor. With a cooling fan to keep the transformer temperature in check it works well. I run my LED lights, laptop, and internet hardware from it. Run time is about 18 hours but I can stretch it to 24.
The battery charging is indeed as described in the video, i.e. using the inverter to do it. Charge current is low (maybe 2A at most) and after running down the time to fully recharge is almost 48 hours. I'm curious to know how the inverter charging would interact with an external "fast" charger (well, faster, anyway - 10A to 15A). If I understand it right, the fast charger would raise the battery voltage seen by the inverter. The diodes would be back-biased at the higher voltage, so the collapsing magnetic field would have to induce a higher voltage than that in order to forward bias the diodes. What happens then?
Ideally the current from the transformer would just charge the battery alongside the fast charger and that would be that, but I don't believe it. I have a feeling the inverter and external charger would end up fighting each other somehow. Maybe the charger would just be confused because its output current is now pulsating in time with the inverter current pulses. Or maybe the charger wouldn't notice and any reverse current would be blocked by its rectifier or whatnot. Or maybe the inverter would force current back into the charger and possibly damage it. Or the increased voltage stress due to the inverter having to overcome the voltage imposed by the charger would damage the inverter some way.
I'd like to believe the ideal case where the fast charger and inverter just get along and basically work normally. I don't believe it though, and would like to test it but don't want to risk damaging anything. Has anybody ever tried this sort of setup and gotten results (good or bad)? Or does anyone have a better idea of what the interaction between the inverter charging and an external charger would be?
Felicitaciones! Me parece un video muy completo y has ganado un seguidor, reunir todos estos datos, la presentación y la explicación han sido espectacular!, gracias por tu dedicación y tiempo,have a nice day!
Hi mate. What's your view on the reliability of Neutral on the output of a UPS? There is a notion in my team that when a single-phase installation takes place, it should be protected with a 2-pole circuit breaker because UPS Neutral may be somewhat dangerous, unlike in typical installations when Neutral is hard-wired to the N bar or similar. Is this because we regard a UPS as a black box with a possible flaw?
BTW, this patent is expired, and let's just (ab)use it in our designs ;-)
Can we upgrade UPS with normal 12v Lead Acid battery to LiPo4 battery.
All very interesting as normal and I'm not that technical but my question is what's a "brick dunni" as Dave mentions. 🤣 We don't seem to many of those in the UK!
Well done Dave, a hefty Tuesday video bringing us a complete explanation of these various UPS technologies. Great tutorial!!
Great video.. I'd love to see some some scope captures of the current flowing into the batteries during charge. Have a current probe?
Yeah I agree that (HV)DC system has improved and looks appealing But AC was responsible for the birth of everything that you saw around you from wireless tech,robotics.....goes on but you know it too. " love to live in a world without AC mains" sounds ungrateful.Maybe I am being over sensitive here. I know we all want to get better and smarter and evolve into a better system. Trust me there is no perfection at the convergence point near infinity there is always something. AC/DC just keep rollin
This should not be a problem at all. First it's just 50Hz, so no worries about the speed of the diodes.
Then according to the datasheet the diode can take 75 amps (300A pulsed). Most LA batteries don't like charge currents over 0,3C. So it would take approx. at least a 300Ah battery to overload a single diode. Sure doesn't look like one.
Btw. since the diodes are thermally coupled through the heatsink, it's very improbable that only one of the parallel diode will conduct anyway.
also looking forward to a followup video with oscilloscope poking.
Too bad it's a rather "uninteresting" design internally(it's just "beefy" for the power), i've seen a SURT5000 (realtime, online) and it's an absolujte joy to see inside, they don't have a single big transformer, it's all toroidal core(and several) high freq transformers inside, also it had ~ 8 BIGGER caps as well and the pack operates at 96V
While i agree no-one is ever satisfied, i'd be VERY interested to see a follow up video at some time comparing the stepped approximation sine waves and how true the sine wave outputs are, and what impacts, if any it would have on the devices. I bought a cheap UPS from jaycar which cost a little more than the batteries i needed to fix my SmartUPS, but everytime it switched to battery, the computer rebooted! so i replaced the batteries in the decade old SmartUPS instead.
It looks like Eaton has purchased the Best Power brand (might have been owned by another company prior to that. I wonder if Best Power sold off the patent rights to APC before being bought up... Afterall, Eaton makes the Powerware line of UPS's (we use a double conversion unit of theirs for our small server farm where I work). I wonder if they use the same charging topology as APC...
I have a comment about online UPS.. I have Liebert GTX2 online UPS and it works slightly different - input AC is rectified - each half period to one capacitor bank, here is paralelly connected also DC--DC inverter from batteries which works only when power fails. And also there is connected some switching circuit which generated AC again to output....And UPS output is NOT ISOLATED. There is no transformer inside, in fact line neutral is hardwired through from input to output.
i have a forza sl-751 ...ups and i would like to remove the 5 minute timer but i cant seem to find it was wondering if it was 1 of the relays....please help
Hi i have one APC 3000 rack, i tried to tun it on but seems does not work on battery mode just line mode. Could you please tell me what is happing? thank you
thank you!!!!! i want to give you a hug!
you exactly solved my Problem!
Dave to get a sine wave 50 hz with pwm switching on H bridge at not a high frequency
only 50 hz on H bridge but high an low Technic and PID algorithm when charging start
you listen some voice not only fan but different this time start high frequency on H bridge and storing current on battery
Body or substrate diode should not be used, especially in when you got 4 mosfets in parallel. I think they must have synchronous control over the mosfet to do diode emulation. The loss associated with using the body diode is too high, not to mention the issues with current sharing between the 4 mosfets when each one is at different temperatures
It seems to me that the charging of the battery is continues as long as the battery is connected. Then you will have an uninterrupted power supply limitless. Free energy.
Unless my memory fails me there is a hosting company here in sweden that ripped all the AC stuff from ther servers and just convert all power to DC and then send it off to ther servers since it was more effishent to do it once for all then in each and every server.
Wouldnt it be easier to change the order in which these devices are currently the power is converted from 230V AC to 12V DC back to 230V AC and then in the Power supply to 12V DC
my suggestion would be first to go down from 230V AC to 12V DC and putting the battery and PC load in parallel
Aaaargh if you and the people you bought it from have been storing the UPS with the batteries plugged in they are already dead! You should let them charge and then unplug them if you want to store the unit and then in few months intervals plug them in and charge them and then plug them out again.
I grabbed two HP R3000 XR UPS's a while ago, unfortunately UPS(the shipper) managed to throw it off a cliff. Arrived in pieces but I managed to fix one of the two units.
I'll post some pictures on the EEVBlog forum if I can find them.
See tesla500's series of videos for a teardown and operating principles of a similar APC SmartUPS. Including scope waveforms and descriptions of the charging circuits and inverter circuits.
Videos: KJj3H00idh0 6yMNlU9gueU and pdTkTY8mbJE
What is a galvanic isolation? How does it protect one who touches the isolated side of a transformer from electric shock and connected equipment from damage. All I know is that there is no physical connection by means of wire and whatnot.
hi anybody can help me out to get total technology transfer to manufacture
online ups 1 kva to 500kva
Don't all these circuits exhibit dropouts during switchover?
Profit i will be buy some BitCoin for what foto Pusher Coin😮😮😮😂😂😂😂😂
@Giza ,Like you could do any better working in the patent system. What you are suggesting is obvious to everyone. Just because technology switches rapidly doesn't mean the paths that were taken to get to this point is trivial.
further ironic is that the DC-DC converters for buck and boost regulation use AC 200KHz type frequencies in the switching regulator. It's all AC to DC to AC to DC etc... conversion, just more efficient when closer to the load.
I have an APC Smart-UPS XL Modular 1500VA. acquired from a local server management building after upgrades. I also have a few of those small 400W personal computer ones, only one with a battery still, the rest dried out.
The patent is a good example of something legit in the US patent system... something innovative that hopefully made the original inventor quite a bit of cash. Better than all these bloody software patents :yech:
Best Power Technology was in Wisconsin. They're out of business. I knew one of the engineers there. They built excellent stuff but unfortunately they ONLY built excellent stuff, not the crap that most people are willing to pay for, so they went bust.
My company actually was spec'ing UPSs to go to Nigeria about 20 years ago - APC told us flat out that their units would NOT deal with the power there, and suggested Best. We tried an APC anyway and it died in less than 3 days.
have had an UPS on my computer system since 2006. Saved my arse plenty of times.. Maybe time to change the batteries in it. But the diagnostics say all is 'Normal'
Vis-à-vis:
UPS Status: High Efficiency
Auxiliary Mains Star Voltage (V): 240
Output Star Voltage (V):: 237
Output Load (%): 30
Battery Capacity Remaining (%): N/A Battery Voltage (V):: 27.6
Internal UPS Temperature (°C): 25
So I have one of these units that two of the diodes on the white leg of the Transformer blew up on me, and I'm not sure why. Do you think I can just replace them?
Even for cheap mosfets the reverse recovery rate is
Wait a secound? H Bridge into the Iron core? So they use Iron core to give a square wave? Isn't that a horrible idea? Or is it just 50Hz Square wave? What is the output at all?
For the online type, does it matter which type of power source is used on the DC side or if there are multiple power sources? (like 12V lead batterys + solar panels used simultaneously..)
Long long time ago. due to misconfigured Powerchute software, we have the whole NT domain pop-up Shutting Down Alert Messages broadcast to all users...LOL, what a embarrassment then. Also many UPS vendors having difficulty to configure their software on Unix Platform and commission it.
No auto-transformer. Did you figure out how the mains voltage regulation works as there's only effectively one transformer that does everything? Please can you plug this thing in and put various loads on it, and under-volt and over-volt it and display the waveforms.
Great video. I've learned a lot from watching your videos. I liked the bit of theory at the beginning. It helped me understand better what was going on and being said during the teardown. Keep up the good work
The way comments were arranged, it shows that the video was created before the "reply" feature is added in TH-cam
I have scored from my school 2x 390W UPS (APC smart ups 620) and it is interesting, that they work only, when the battery is connected. So my theory is, they're using the battery for the control circuitry like just the battery, because the battery when it's discharged, its voltage is abou 11 or 10 volts, but it is still high enough for linear voltage reg to do its schedual job. Very interesting UPS, i've tried them, but i can't get to work the inverter, like it just says, its overloaded and then it shuts itself down, even, when there's no load connected and th other one fails on the selftest.
i have a installation you ups power it great speech video
you can use battery
Seriously, if people want to see that then they should make their own damn videos! Don't ever let people get to you -- your videos are EASILY the best on TH-cam (jpkiwigeek ties with you though :P )
Dave, have you considered gating an "endoscope" thingy to get some shots from inaccessible places ? The added complexity of editing might make it not work it, but why not try it.
Got a couple in the garage that I need to do a teardown on sometime. Two SmartUPS 2200RMXL (one 5U, one 3U), a Galatrek Microbak ferroresonant 1.5kVA UPS and a transformerless NuWave Powervalue 12kVA.
Not in this design, they are used to filter the h-bridge rectified back-fed mains into the battery, which isn't going to like AC rippled DC charging current.
It's quite unlikely that substrate diodes are used as rectifying diodes. More likely they use a synchronous rectifier.
So good, love how you explain everything, keep it up! Cheers from Sweden!
So this ups is using a buck charging circuit, which is more efficient and uses less parts.
Try to send GW range of power Without AC Transformers...
(Even High frequency Transformers for GW range are still in baby stages).
See tesla500's video watch?v=6yMNlU9gueU He shows charting topology and waveforms near the end of the video.
very good and simple explanation