hybridfree/eevblog-posts huggingface dataset:
Can anyone explain? - Page 1
Forum section: electronics / general

author: Jane
author_rank: Frequent Contributor
timestamp: August 31, 2022, 08:27:19 pm
content: I have a small off-grid FV (about 5kW). MPPT is connected with invertor input and also with battery cells( but battery cells are also connected with the invertor.)When a load is connected ( and invertor starts) what percentage of kW goes directly to invertor from MPPT and how many watts are taken from battery cells to invertor?Thank you for help

author: DC1MC
author_rank: Super Contributor
timestamp: August 31, 2022, 08:39:29 pm
content: Quote from: Jane on August 31, 2022, 08:27:19 pmIt gets a bit simpler if you consider the inverter input as "hungry, never to be sated battery that always charge", so the MPPT controller could provide a a solar radiation depended current at the battery, where the inverter is connected as well (directly or indirectly).If the batteries are discharged the current is split in between the inverter and the batteries, if the batteries are fully charged the available current goes to inverter, if the inverter needs more current it start to suck from the batteries as well (exactly as you would connect an empty battery in parallel with a charged battery). In the end the inverter can use whatever the MPPT collects from the panels plus (and only if the external load needs it) whatever the batteries can offer.It truly depends on the load of the inverter and the available solar power, in my smaller installation I have amp meters on the wires and can see when increasing the load the the current going into batters decreases and increasing the load more, the battery current reverses the direction and start to flow to the inverter.In current sunny days, I mostly have the MPPT feeding the small load by itself only, the batteries are just full and waiting for the chance to dump their load as well.

author: fordem
author_rank: Regular Contributor
timestamp: September 02, 2022, 02:52:19 am
content: There's no simple answer to that - it's going to vary depending on the battery's state of charge, the load on the inverter and the solar irradiation at the precise moment of measurement - it's going to vary from day to day, almost minute to minute.
Diode clamp not needed for UC3854 PFC chip? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 29, 2022, 10:30:27 pm
content: Hi,Second page of slua177A talks of a diode ..."one diode to clamp the voltage amplifier output".Please confirm, that there is no such diode ever needed in UC3854?To what this line refers, is a mystery.Sometimes, if a really wide mains range is in order, then the Voltage error amplifier output of UC3854 does sometimes get clamped to 2V max........but that is not "one diode to clamp the voltage amplifier output"....rather, that would involve and opamp based clamping circuit.SLUA177Ahttps://www.ti.com/lit/an/slua177a/slua177a.pdf?ts=1661812201694&ref_url=https%253A%252F%252Fwww.google.com%252F
Mains on/off lightswitch shortened life & switchmode loads? - Page 1
Forum section: electronics / general

author: peteb2
author_rank: Regular Contributor
timestamp: August 19, 2022, 04:15:51 am
content: I've searched through previous posts here on this but i need a simple answer. The situation is from 230Vac Mains, the change to using LED lights (over flourescent) that invariably consist of an internal SM regulator per fitting to create the 400 plus Vdc for the internal LED strip. Switching off results in the room wall lightsitch arcing as the combined switchmode regs all "try to keep the current flowing".... Question: is there a standard snubber module accessory that can be connected across the switch contacts to prevent the arc effect. So far this year the switch has had to be replaced 3x.... If not what X or Y class capacitor might be the option? Apologies if this has been discussed to death elsewhere. Any info appreciated...

author: Faringdon
author_rank: Super Contributor
timestamp: August 19, 2022, 07:33:39 am
content: It sounds like it must just be those particular lights.Ie , they dont have sufficient current limit or mains input under voltage shutdown.What power is being drawn through that switch when its opened?There are RC snubbers for switchs and relays etc, but they wouldnt normally be needed for a mains LED light bulb.....most LED bulbs, even the cheap ones, tend to have some kind of inherent current limit. They usually work in some kind of peak current mode control, and they just cant draw more than a certain level of current.....which isnt very high for a single led light bulb.......its not enough to be blowing wall switchs three a year.If a switch for mains LED light bulbs was going to be damaged, then you'd expect it to be at switch-ON, when led bulbs with insufficient inrush limitation result in contactor arcing while it bounces, and is due to the high inrush current.I am wondering If maybe your led lights are back fitted into old iron-core fluorescent lights, where there is a big iron cored inductor at the front end, and its the current in that that is getting broken when you switch off...and causing the arcing during the normal switch bounce.

author: Ian.M
author_rank: Super Contributor
timestamp: August 19, 2022, 10:04:08 am
content: I'm not usually one to agree with Faringdon, but there's definately something odd going on with your lights.How many lights are wired to the same switch?Is it possible you are exceeding the switch's current rating in normal operationHave you tried a different brand of switch?If you are running a switch right at its current rating, and switching it frequently expect a short life for it! Derating may be required.

author: GoneTomorrow
author_rank: Regular Contributor
timestamp: August 29, 2022, 09:19:26 am
content: My garage lightswitch often arcs when turning off 3x 20W Philips batten LEDs. But it's because it's old and gone a bit gammy. Lost its quick opening snap.It's a crummy Clipsal, the PDL 600 series lightswitches I also have around have a much more convincing snap when turning off, and don't arc. I'll get around to swapping it one day.
Charge Around Australia - Page 1
Forum section: electronics / general

author: AndyBeez
author_rank: Frequent Contributor
timestamp: August 19, 2022, 07:32:11 pm
content: Solar goes on an Aussie road trip:QuoteOne to watchhttps://chargearoundaustralia.com

author: f4eru
author_rank: Super Contributor
timestamp: August 20, 2022, 06:36:58 am
content: Nice technology demonstration.The low efficiency is a bummer in a mobile application tho. Also, loose flexible strips might be impossible to use at the smallest whiff of wind.
Testing a UCC28070A Dual PFC control chip? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 14, 2022, 08:01:41 am
content: Hi,I have purchased two UCC28070A’s (Dual PFC control chips) which appear to be ESD damaged.The UCC28070A contains control for an "A" PFC stage, and a "B" PFC stage.We first put the UCC28070A’s on their control PCB…we then apply Vcc=12V. We then apply 2V to both the VSENSE and VINACP pins. (via two resistive dividers).So then they should simply provide a pulse train of duty cycle 0.9, since that is the maximum duty cycle that we set with resistors on the DMAX pin.The rest of the pins are set up for operation of a single PFC stage. The “B” PFC part is disabled by us grounding the “B” current error amplifier output (CAOB pin grounded). So we only use the “A” PFC control part of the chip.For this test, there is obviously no signal coming into the current sense pin (CSA). That pin just basically sees the low impedance of the burden resistor. The “B” current sense input is grounded.UCC28070A datasheethttps://www.ti.com/lit/ds/symlink/ucc28070a.pdf?ts=1660464063939&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUCC28070A%253Futm_source%253Dgoogle%2526utm_medium%253Dcpc%2526utm_campaign%253Dapp-null-null-GPN_EN-cpc-pf-google-eu%2526utm_content%253DUCC28070A%2526ds_k%253DUCC28070A%2526DCM%253Dyes%2526gclid%253DCj0KCQjwuuKXBhCRARIsAC-gM0htEzmQXylIBLe0P804b4bjRCp0-2JA0g-Bi6dgrNRquXS-aSul4iIaAg4-EALw_wcB%2526gclsrc%253Daw.ds______----_______Results of above:The first chip was dead on power up…..it was drawing 25mA of current (above its Abs Max), and there were no gate drive pulses coming from its GDA pin.The second chip at first passed the test, and gave a constant 0.9 duty cycle gate drive from its GDA pin. However, it was clearly malfunctioning when driving the PFC stage. With 70W load, it was bursting ON/OFF (18ms switching, 32ms not switching). I then re-tested the UCC28070A as above, and after a while the constant stream of gate drive pulses got extremely erratic……going away and coming back….even scrolling from low duty cycle to max duty cycle. The outputs of the current and voltage error amplifiers were batting up and down erratically.Would you agree that the above means we have two ESD damaged UCC28070A’s?I have emailed Texas, but we are a small outfit, and not even allowed on their forum, due to no company email address, so we don’t expect a reply.
TPS54821 power good toggling! - Page 1
Forum section: electronics / general

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: August 04, 2022, 02:45:24 pm
content: HiI have designed a new PCB for TPS54821, it would be used to power an Artix FPGA, so it would generate 1V, 1.8V and 3.3V, with three different Chips, I have used the Power good and enable pins for Power sequencing.The problem is that the 1V output power good signal would toggle so it would not allow the 1.8V and 3.3V stages to power up, But if I disassemble the 1V regulator the 1.8V and 3.3V parts are working properly, I have put the scope on the output power good output of the 1V chip and it's toggling, surprisingly it would output 1V and I can load it with a dummy load!Here is the schematicsDo you have any Idea what's going on?

author: Faringdon
author_rank: Super Contributor
timestamp: August 04, 2022, 03:06:11 pm
content: TPS54821https://www.ti.com/lit/ds/symlink/tps54821.pdf?ts=1659618262363&ref_url=https%253A%252F%252Fwww.google.com%252FYes the power good shouldnt toggle...its an open collector pin so it should pull down when power is good, and "let go" when power is not good. I wonder if your chip is ESD damaged, as you say you are able to power a dummy load from the power good pin?...that shouldnt be possible.These tiny 0.5mm pitch chips are super sensitive to esd damage, and also even slight overheating when soldering them will kill them.

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: August 05, 2022, 09:17:24 am
content: Thanks for the tips, I did not say I get power from power good pin, I said I could load the output, also I have put 2-3 different chips because I thought the chip was damaged, But I got the same results.

author: Faringdon
author_rank: Super Contributor
timestamp: August 05, 2022, 12:31:00 pm
content: OK, so you are using the power good as like a signal output to tell the other regulator(s) to startup?, so that they start up in correct sequence.But the power good signal from the 1vout regulator is not working properly?...and instead of asserting and staying asserted...its going on/off/on/off....etc?Is the layout really tight?...you have nice ground plane etc.?...decoupling caps right on the pins? Those control chips with internal fets tend to turn the internal fet on ligthning quick...and the noise can cause issues if layout isnt super tight.You coudl just make your own external sequencing circuit using comparators (with hysteresis) and dividers....i think you can even get chips which you hook up and they give you a power good output for say 1vout, 1v8 out etc etc.........___But otherwise....Try removing C85...this coudl be the best one...or replace it with 1k in series with 470p say.Use some 100n 0603 x7r caps right up snug to the power switching current loops.Put some little capacitance on the EN pin.....Change C86 to 100pF to 1nF.Change R48 to 1k.check underpad is really soldered
Please explain this to me - Page 1
Forum section: electronics / general

author: SScattered
author_rank: Contributor
timestamp: August 04, 2022, 04:58:49 pm
content: https://imgur.com/a/heOKsQuThis is a video a friend of mine send me few days ago. He's working in a Solar system company. The measurements they are taking are directly from the transformer (33KV to 400V). Finally they are measuring the voltage with respect to the earth they have installed for the Solar System. He told me that there's around 7-8m between transformer earth(neutral grounded) and solar system earth. Also please note that, transformer neutral is grounded. We have TT system in my country.Also, this measurements are taking while this transformer providing power to a factory. I don't know the capacity of the transformer.As you can see in the video, one of the phases (Black) voltage with respect to Solar system earth showing around 37v and other 2 around 378V.So my question is why Solar earth and Black phase is having 37 Volts? It cannot be a multimeter issue for sure. Is there a plausible explanation or it's multimeter issue. It might be a bit hard to see that it's 37V, please see the dot.PS: Black probe at the end of video he's probing it against the SPD terminal (Solar earth)

author: Faringdon
author_rank: Super Contributor
timestamp: August 04, 2022, 07:13:03 pm
content: It woudl be good to explain if you had some alligator clips and 4 diff probes, and a 4 channel scope, and could show volt waveform of Black/grey/brown and solar_earth with respect to transformer neutral.Or say if you had a battery scope for this, and show all 4 volt waveforms (at the same time) w.r.t txfmr neutral.

author: wraper
author_rank: Unknown
timestamp: August 04, 2022, 07:33:12 pm
content: I can say that he measured phases against neutral, not earth. And it's certainly not earth against what he was measuring phases in the end of the video.

author: wraper
author_rank: Unknown
timestamp: August 04, 2022, 07:38:23 pm
content: Quote from: SScattered on August 04, 2022, 04:58:49 pmHe also measured 199V to neutral and around 380V, instead of 240V for other two phases.

author: Faringdon
author_rank: Super Contributor
timestamp: August 04, 2022, 09:23:22 pm
content: I think it shows how all the theory surrounding "earth" is often far off.It isnt the same potential across the land....specially when its sandstone soil say.
UCC28070A not sending gate drive pulses - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 03, 2022, 06:40:05 am
content: Hi,{EDIT....Please do not waste time reading this...it was a case of a likely ESD damaged UCC28070A...when changed the problem was solved...........END OF EDIT}Have a daughter board containing the UCC28070A PFC controller. Want to test the UCC28070A before letting it loose on the PFC power circuit. It is not sending any gate drive pulses. Have fed it 12V. Its drawing 25mA as seen through the input 10R resistor, this seems a lot. Its got a correct 6V on its VREF pin. The Soft start capacitor isnt charging up....just stays at 0.9V or so. I did see ~6V on soft start cap at first but then never again.There arent even any gate drive pulses when its first powered up. (did sample/hold on gate drive when powered up to prove this).By the way, i have injected 1.9V on to the Vsense pin and onto the Vinac pin.I have a properly working sync pulse circuit, but when i send those pulses to the UCC28070A , the sync pulse cct stops working....and it looks like voltage is being back-fed from the UCC28070A to the sync circuit.Anyway, i also tried the UCC28070A in not_sync'd mode and it still doesnt work.Being a hobbyist, i am not allowed on to the ti.com forum.Do you know what might be wrong?The datasheet doesnt say what voltages are needed to be injected into the vsense and vinac pins in order to get the chip sending gate pulses....just says above 0.7V.UCC28070Ahttps://www.ti.com/lit/ds/symlink/ucc28070a.pdf?ts=1659508725268&ref_url=https%253A%252F%252Fwww.google.com%252F.......UCC28070A is rated for 20mA abs max supply current, so it looks like mine is fried...i used full ESD protection throughout. I am wondering if the chip shortage is meaning almost_empty reels of components are being re-reeled, and this done without ESD precautions.In a recent other job a load of control chips were wadgered.(Eagle Pro layout and schem attached)I am just wondering now......i soldered this board up with an Eagle YO61 solder station......the solder tip is earthed only if the cylinder screw is tight.......i did notice during soldering, that the cylinder screw had loosened right off, and then there's no earth connection to the solder tip.......so maybe that could have ESD blitzed the UCC28070A?.......What would you think the likelihood of ESD damaging a UCC28070A with a non earthed solder tip? I did have to drag solder the UCC28070A.If it is ESD damage, then i wonder how the CD74HC123M didnt get ESD damaged (the second one i used), because CMOS chips are renouned for ESD susceptibility...but then again, it is a 1.27mm chip ...i am convinced that these tiny <=0.65mm pitch chips, like UCC28070A, are more susceptible to ESD damage?Eagle YO61 solder station:https://www.ebay.co.uk/itm/373892836026?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338722076&customid=&toolid=10050
Any tips or warnings for low-voltage high-power boost conversion? - Page 1
Forum section: electronics / general

author: karpouzi9
author_rank: Contributor
timestamp: July 31, 2022, 09:36:38 pm
content: Thanks.

author: David Hess
author_rank: Super Contributor
timestamp: July 31, 2022, 10:38:19 pm
content: At such high currents, parasitic inductance and resistance, including ESR of capacitors, becomes increasingly important, which places severe demands on circuit layout.Using multiple modules in parallel is definitely the way to go, and proper phasing between modules will lower ripple current requirements.

author: f4eru
author_rank: Super Contributor
timestamp: August 01, 2022, 01:43:12 pm
content: Quote from: karpouzi9 on July 31, 2022, 09:36:38 pmThe simple answer is : NO. Don't.Take the load on a series of cells instead of paralell, if your load is more comfortable at higher voltage.Voltage balancing and co. is much simpler than an impractical DC/DC converter.

author: Peabody
author_rank: Super Contributor
timestamp: August 01, 2022, 02:46:58 pm
content: Isn't the efficiency of a stack of cells effectively 100%? As opposed to whatever you lose in the boost process.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 01, 2022, 03:07:48 pm
content: If you need regulated output voltage (like 12V +/- 2%) over the whole state-of-charge, then you are going to need a switching converter anyway, so boosting from 1s (3.0 - 4.2V) to 12V is not a colossally bad idea, unless the current is very large. Bucking from 5s to obtain 12V would allow smaller battery current.Note that both buck and boost topologies require an extra switch to disconnect the battery (boost lets current-unlimited Vin directly to the output through the diode; buck lets voltage at the output flow through and charge the battery through the body diode of the MOSFET).For unregulated rough voltage ranges, just use desired number of cells in series.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 01, 2022, 05:16:08 pm
content: I think you are overestimating the risk of cells failing in series configuration. The only viable solution is to use high quality cells that fail rarely enough. If you use cells that are prone to fail, I suspect they might have safety issues in parallel configuration, even if you fuse them separately. Series configuration at least makes the product dead (by BMS) when a cell fails, which is a good thing safety wise. Availability wise, obviously not - but that can be only solved by cell quality improvement.
Power connector contact resistance - Page 1
Forum section: electronics / general

author: luky315
author_rank: Regular Contributor
timestamp: July 29, 2022, 06:43:11 am
content: I have a SMT power connector (custom made) with a 30mm² tinned copper pad. My qustion is: What is (approximately) the contact resistance from this connector to the PCB pad if a standard lead-free solder is used?

author: Siwastaja
author_rank: Super Contributor
timestamp: July 29, 2022, 06:48:56 am
content: You could calculate it using tin's resistivity and assuming some solder layer thickness between the PCB pad and component pad, like 100µm.But I'm sure the result will be so small that everything else matters more: specifically, what kind of track/fill pattern are you then using on the PCB?

author: luky315
author_rank: Regular Contributor
timestamp: July 29, 2022, 06:56:06 am
content: My problem is that I have no Idea how thick the solder layer is. The PAD on the PCB is massive (40x40mm)with 4 Layer 70µ.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 29, 2022, 10:46:33 am
content: Well, if you use a 100µm thick stencil (my favorite thickness, I prefer it over 120µm now), doesn't that kind-of set a maximum limit on the solder thickness?In reality, the paste layer has deliberate gaps in it (segmentation) spreading the paste over larger area (reducing thickness), and the flux also gasses and/or flows out of the mixture, so I would expect the end result is significantly thinner than the original paste print thickness. But you can't go wrong if you assume the worst and calculate using stencil thickness.

author: Faringdon
author_rank: Super Contributor
timestamp: July 29, 2022, 01:46:19 pm
content: ....Taking Rho of unleaded solder as 1.3e-9With your 30mm^2, and 50um, this gives resistance of some 217 nanoOhms.AYK, if you have thermal reliefs etc, then they will likely swamp out the resistance effect of the solder fillet.So the pad is about 5.4mm by 5.4mm ~30mm^2?.....or nearer the 40x40mm (=1600 mm^2) that you later mention?

author: luky315
author_rank: Regular Contributor
timestamp: July 29, 2022, 03:19:04 pm
content: I've got measurements in a german document which are in the region of 50µm solder thickness, which makes sense, because the solder paste has a lot of volatile components (flux etx.).

author: Siwastaja
author_rank: Super Contributor
timestamp: July 29, 2022, 03:37:25 pm
content: BTW, it's hard to guarantee perfect solder fill between the pads, unless you can X-ray the units, you should assume some amount of voids (basically air / trapped gases). So if you calculate at 100µm thickness and 70% of the pad area, you are pretty safe.
Smart Meters and erroneous night time power 'consumption' and rebates - Page 1
Forum section: electronics / general

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: July 25, 2022, 04:39:26 pm
content: This was prompted by Dave's recent video on night time apparent power 'consumption' of PV inverters.Completely co-incidentally I recently learned of someone in the UK who had a PV system, and who had been complaining of excessive charges for 'night' power (in the order of a low few hundred W excess to what he could see as normal background) reported via his Landis & Gyr 'smart' meter. No 'fault' could be found.After about 2 years of pursuing this, he eventually got a VERY substantial rebate and the meter replaced.I can only assume it might have been measuring VA not W, which as we know is not the deal for a domestic user, and somehow could not be reconfigured to stop doing this.Anyone come across this?

author: fourtytwo42
author_rank: Super Contributor
timestamp: July 25, 2022, 07:42:55 pm
content: I have just acquired (by house move) one of these wretched smart meters, I too have noticed it registering night time consumption (with everything apparently switched off) however the house has some daft accessories such as wall power outlets with inbuilt USB chargers and an unswitched shaver outlet so I have yet to pin down the SM accuracy.I am also having the house rewired as it is substantially 1950's rubber so some overnight consumption could even be cable leakage!! Like many others I believe we switched off and put in a drawer the in house display to save energy and worktop space as it told us nothing useful at all.
Shutting down the UCC28070A PFC controller? - Page 1
Forum section: electronics / general

author: zenerbjt
author_rank: Regular Contributor
timestamp: July 23, 2022, 04:54:59 pm
content: Hi,Can we simply shut down the UCC28070A Boost PFC controller by grounding its transconductance current error amplifier outputs (CAOA) ?The below App Note seems to suggest this is possible (Q2 grounds the CAOA output)SLUR033 App Note:https://www.ti.com/lit/df/slur033/slur033.pdf?ts=1658554812841UCC28070A datasheet:https://www.ti.com/lit/ds/symlink/ucc28070a.pdf?ts=1658587094824&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUCC28070AThough i wondered what if the transconductance current error amplifier somehow goes into some "zone" whereby its higher output transistor gets fully saturated ON, so that its railed high?...then it gets grounded and there's smoke?
Fires in DIY e-bikes due to incompatible batteries and chargers - Page 1
Forum section: electronics / general

author: AlbertL
author_rank: Regular Contributor
timestamp: July 16, 2022, 10:30:33 pm
content: https://www.dailymail.co.uk/news/article-11020833/They-like-bombs-waiting-explode-Warning-DIY-e-bikes-spark-rise-house-blazes.html

author: uer166
author_rank: Super Contributor
timestamp: July 17, 2022, 03:34:37 am
content: Might be an unpopular opinion, but this is not a good look for home-made (or otherwise) e-mobility devices, and is an issue not just in UK. It's ridiculously hard to get this stuff right (just look at Louis Rossmann's situation with this and him blaming everyone under the sun but himself).As such, you either accept that this will keep happening at some cadence that is much higher than commercially developed compliant devices, or you'll have to enforce a stop-sale of the janky kits somehow, enforce use of compatible chargers with DRM-like lockdowns, etc. People really don't like that, and rightfully so.The BMS systems are crap, the cells are rejects/crap, the motor control systems suck and regen/backfeed more than the cells can handle, the chargers have equally bad voltage regulation to the point of relying on the BMS to cut-off the charge session (removing one of the two safety layers). There's no clear solution to this specific issue when it comes to e-mobility, doubly so for home-install kits..

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 17, 2022, 04:47:52 am
content: Even the commercial ones can be sketchy, my parents got a couple and the chargers have that Chinese "Shake Hands With Danger" power brick look and feel, no safety approval marks, 54.6V on the usual 5.5x2.1mm barrel connector. At least the batteries are contained inside the metal frame.

author: f4eru
author_rank: Super Contributor
timestamp: July 17, 2022, 03:26:34 pm
content: Not only e-bikes.- "Hoverboards" and e-trottinettes- R/C model stuff- DronesAll use mediocre quality stuff, lacking safety devices.R/C model stuff is the worst offender, as it is mostly using no BMS at all.Makig e-bikes safe in general will need to have proper prices on e-bikes with safety. often, those are priced like small cars with no other justification than lack of competitive producers.Once this market is demand constrained, with proper price competition, it will be safe.

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 17, 2022, 04:20:41 pm
content: Also don't forget those mains power bank things that are just an inverter and something on par with an ebike battery in a box. Might be faster to list what's generally safe than potentially hazardous.I doubt this problem goes away without something better coming along and the spicier lithium ion chemistries falling out of favor, and enough time the "recyclers" run out of a steady supply. Or some heavy handed regulation, at multiple levels, to ensure safety and greatly slow the flow of the chinesium.
Selecting an AC power supply for testing a shunt regulator - Page 1
Forum section: electronics / general

author: j_omega
author_rank: Contributor
timestamp: July 13, 2022, 03:01:53 pm
content: I am working on design verification of a rectifier/regulator circuit which converts the AC output from a fixed-magnet alternator into a 14V DC source. The regulator is a shunt-style design where any unused power is shorted to ground through SCRs (schematic). This design depends on the alternator only being able to deliver a limited amount of current in a short-circuit configuration (~16 amps).I built a test system (photo) for my lab bench which uses a VFD and AC motor to spin the alternator at operational frequencies. This works but is noisy and dangerous. I would prefer to replace it with an AC power supply such as the BK Precision 9830 series. However, this would result in an over-current condition on the supply when the SCRs turn on.I am struggling to find an AC power supply that would enable me to test a shunt regulator without blowing a fuse or tripping the over-current shutoff. Any suggestions?

author: Gyro
author_rank: Super Contributor
timestamp: July 14, 2022, 08:14:48 pm
content: This looks like effectively a double post of your request in the Test Equipment section...https://www.eevblog.com/forum/testgear/looking-for-a-20a-500w-ac-power-supply/This is generally frowned upon as people find that they have wasted time when they see that other people have duplicated the information that they have provided. As you are getting useful hits in the other thread, I suggest that you ask for this one to be locked.

author: j_omega
author_rank: Contributor
timestamp: July 14, 2022, 08:31:59 pm
content: Quote from: Gyro on July 14, 2022, 08:14:48 pmHow can I request the lock?

author: Gyro
author_rank: Super Contributor
timestamp: July 14, 2022, 08:48:20 pm
content: There's a 'report to moderator' link bottom right of your post... or you could simply ask people to reply to the other thread instead (it would be a bit presumptuous for me to do it!).P.S. I realise it was a case of second time lucky in picking the right forum section.
Forgot to track ramp signal back to PFC controller - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: July 13, 2022, 12:04:47 pm
content: Hi,Just designed and layed out a 2Kw PFC’d PSU.PFC controller is UCC28070A.I have forgotten to track in the ramp signal back to the PFC controller PCB. I added the ramp producing circuit to the PFC gate drive PCB, but forgot to track the ramp back to the controller.(The Current sense transformer burden resistors are  on the PFC controller PCB)Do you think it’ll be OK to twisted pair wire the ramp signal (with ground obviously) back to the controller…or would you say too much noise would result?UCC28070A.https://www.ti.com/lit/ds/symlink/ucc28070a.pdf?ts=1657631997285&ref_url=https%253A%252F%252Fwww.google.com%252F(The ramp is needed to reduce mains input current distortion. It is only needed near the mains zero crossings, and during light load)

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: July 15, 2022, 12:52:56 am
content: No.One maybe.Many no.Do your views disagree?Yours truly.

author: Faringdon
author_rank: Super Contributor
timestamp: July 15, 2022, 08:30:42 am
content: Thanks, I must admit, i do have a capacitor of an RC filter on the CS pin, so it "should" be OK.But in a 2kW offline PSU, having signals on a wire (albeit twisted pair) and bringing that wire right to the CS pin of the UCC28070A sends shivers down my spine a little.Getting the board re-done will cost some £250 incl shipping, and takes maybe up to 3 Weeks.....(i dont know why, maybe the weight, (5.6kg for five) but it got stuck in customs for a while , even though i eventiually payed the customs fee)..other (smaller) PCBs from China came much quicker.

author: Gyro
author_rank: Super Contributor
timestamp: July 15, 2022, 06:01:18 pm
content: It would be unrealistic to expect not to have to do one or more board passes. It is sensible to find and work around (where feasible) as many errors as possible first though.
Effect of the batteries on the PCB design! - Page 1
Forum section: electronics / general

author: Swapnil
author_rank: Contributor
timestamp: July 11, 2022, 08:07:29 am
content: Hello, everyone!I have a simple doubt, and that is what is the effect on the PCB design if we connect a large of batteries in parallel. Currently, my system has 2 batteries in parallel, and we are planning for 12 batteries in parallel. So, will the design of the board depend on the capacity (Ahr) that will be coming from the batteries or the power consumption by the peripherals on the board?P.S: Battery specs (4S LiPo, 5400mAh, 40C)

author: Berni
author_rank: Super Contributor
timestamp: July 11, 2022, 09:04:25 am
content: There is no information on what your PCB even does.But in general connecting large numbers of lithium cells in parallel comes with its dangers where a faulty cell might find the whole pack discharging into it and making it explode.

author: Swapnil
author_rank: Contributor
timestamp: July 11, 2022, 09:45:08 am
content: Quote from: Berni on July 11, 2022, 09:04:25 amThe PCB will be a Power Distribution Board and my system will also have five thrusters (inductive loads), therefore there will be definitely an inrush current flowing through the circuit.

author: Kasper
author_rank: Frequent Contributor
timestamp: July 12, 2022, 05:05:15 am
content: Looks like your batteries can deliver a fair bit of current.5.4Ahr * 40C = 216A12 batteries * 216A = 2600AHow much current is your load drawing?

author: Marco
author_rank: Super Contributor
timestamp: July 12, 2022, 01:40:21 pm
content: Quote from: Swapnil on July 11, 2022, 09:45:08 amA truly inductive load does not have an inrush current, it starts at zero and goes to short circuit. I'm going to guess you have some kind of ducted fan motors? So it's more accurate to call it a motor load, rather than inductive.Won't the motor controller limit current? As for handling catastrophic failure, if the failure results in a crash any way any mitigations can become irrelevant.
Satisfactory high power offline battery charging solution is finally here? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 28, 2022, 07:58:23 pm
content: Hi,As we conclude from the following…https://www.eevblog.com/forum/renewable-energy/avoiding-reverse-recovery-problems-in-llc-converters/….”LLC converter with series diode” finally gives the Power Electronics world a Low or high voltage, high power battery charging solution without downstream buck or boost stages being needed.……..Would you agree?AYK, hard switching, transformer based power stages can’t realistically be used at >1kW offline, since the noise becomes too high and malfunction of the SMPS control can result…unless you make the switching frequency really low and heavily damp the switching transition…but then the SMPS overall physical size becomes too big.Battery charging was usually considered "not the realm of the LLC" for various reasons......but not any more.....the series diode trick brings it on!So finally…we have arrived! Do you agree?

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 29, 2022, 05:04:46 am
content: Quote from: Faringdon on June 28, 2022, 07:58:23 pmSwitching supplies for welding are pretty common and that's about as noisy as things get - literally a very powerful spark gap transmitter as the load.

author: Faringdon
author_rank: Super Contributor
timestamp: June 29, 2022, 08:25:31 am
content: Thanks, it would be interesting to see what the current waveform to a welder looked like.
Fast NPN's for gate drive transformer? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 26, 2022, 12:18:51 pm
content: Hi,Would you agree, that Q3 and Q2 in the attached (LTspice and jpeg attached) would best be BC849 rather than MMBT2904? -Because Transition frequency is higher.What would be the best transistor to use here?MMBT3904https://www.mouser.co.uk/datasheet/2/308/1/PZT3904_D-2319825.pdfBC849https://assets.nexperia.com/documents/data-sheet/BC849_BC850.pdfDo you also agree that for Q3 and Q2, one should seek amongst low current BJTs (eg <100mA)...because they will be quicker?...since their doping regions are less densely doped?
How do grid connected inverters determine frequency and phase - Page 1
Forum section: electronics / general

author: AussieBruce
author_rank: Regular Contributor
timestamp: June 22, 2022, 07:49:33 am
content: Hi, I’m after some information on how renewable energy inverters (solar, wind) remain on frequency and in phase with a grid load. Wikipedia doesn’t go deep enough for what I’m after. Presumably the principle of operation is that when feeding a substantial grid, the inverter output won’t be able to substantially affect the connected waveform, so problems with feedback instability aren’t significant. Is it as simple as a programmed device such as a micro or an FPGA detecting the + and – crossing points following a small amount of filtering, and using this to synthesize the pattern of switching signals that generate the chopped waveform, based on the required output power level? Or is something more sophisticated involved, such as a PLL that generates a tracking waveform that’s then used for controlling the output switching?If there's a such a thing as a device that does all this, a type number would be useful, the datasheet will tell all. Thanks for any info.

author: Faringdon
author_rank: Super Contributor
timestamp: June 22, 2022, 10:21:50 am
content: QuoteI did a search on this some time back, and couldnt find any such device, so i think either of your stated methods is fine, just as long as you can stay in phase within +/- x%....so yes, the phase detection thing is just a role your own, in either of the ways that you describe.It amazed me how rough the whole thing is....because if too many people in a neighbourhood are inverting into the mains, then the mains will rise too high, and any other residents who want to invert into mains, wont then be able to....because the mains would be too high, and all GTI's detect the mains voltage b4 starting and wont start unless mains is less than 253VAC or so. The governments were going to install hugh battery banks everywhere to mitigate this, and so that more people could invert into mains when they want to.

author: David Hess
author_rank: Super Contributor
timestamp: June 22, 2022, 03:28:38 pm
content: Quote from: AussieBruce on June 22, 2022, 07:49:33 amThose are essentially the same thing. A reference waveform that is phase locked to the power line is used to modulate the output current. Using the reference waveform allows the inverter to ignore noise on the power line.Quote from: Faringdon on June 22, 2022, 10:21:50 amThe inverter can also shift the phase of its about a limited amount to increase its output power without raising the peak voltage.
ICE2HS01G LLC controller datasheet interpretation - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 21, 2022, 12:47:39 pm
content: Hi,We are doing a 2kW HB LLC with ICE2HS01G controller.VMC pin:Why, on page 9 of the datasheet, does the VMC pin comparator "look" at the "CS" pin?.....the CS pin goes from zero volts to peak, every cycle, so how can a comparator be looking at that to see what average level it is at?(The VMC pin decides when the load is light enough that it should go into burst mode)ICE2HS01G datasheethttps://www.infineon.com/dgdl/Infineon-ICE2HS01G-DS-v02_01-en.pdf?fileId=db3a30432a40a650012a458289712b4cSynch Rect:If not using Synch Rects, then can DELAY, SRD and VRES pins be left unconnected?CL pinDoes this represent the peak of the Current Sense (CS) pin?
What to set switching frequency to in overloaded  LLC converter? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 20, 2022, 05:14:46 pm
content: Hi,Do you agree that bottom of page 11 of the following App Note is nonsense?LLC converter design guide with ICE2HS01G:https://www.infineon.com/dgdl/Design+Guide+for+LLC+Converter+with+ICE2HS01G+05072011.pdf?fileId=db3a304330f68606013103ebd94f3e98It says: “During over-current, the load impedence is considered to be shorted”……..how so?.... when its shorted, the load impedance is zero??They are trying to find what to set the switching frequency to during overcurrent.
Way to keep Li-ion battery packs from fully charging without user intervention? - Page 1
Forum section: electronics / general

author: Lupin III.
author_rank: Contributor
timestamp: July 12, 2022, 12:10:49 pm
content: There are a lot of battery powered devices that should be ready to use at any time. I'm not thinking about phones, cameras, tablets and devices like that, but something like power-tools, vacuum cleaners, mowing robots aso. Essentially devices that almost always have 18650 cell based battery packs. If you keep them on their charge port the batteries will be kept at 100% percent all the time, which doesn't really help longevity of the cells, even though the 100% battery charge is almost never needed in use. I would like them to not fully charge, but rather to a level of roughly 70-80% (or about 4V per cell).Of course there would be the way to reverse engineer the charging circuitry and maybe fiddle with some resitor dividers there. But that circuit is often under conformal coating or silicone. I'm talking about the "stupid" case: The battery pack is not much more than a pack with two wires coming out and does not have fancy things like a cell balancing circuitry (but maybe single cell monitoring for safety). I was thinking about putting two anti-parallel diodes into the positive wire, which would reduce the pack charging voltage by about 0.7V, but I'd also "waste" another 0.7V in the other diode while discharging.Do you have any simple ideas?

author: tunk
author_rank: Super Contributor
timestamp: July 12, 2022, 12:16:18 pm
content: Instead of standard diodes, you could try 0.2-0.3V Schottky diodes.Edit: Logical short circuit, a Schottky would work with a single cell(or several i parallel), but not with cells in series.

author: f4eru
author_rank: Super Contributor
timestamp: July 12, 2022, 01:06:49 pm
content: Quote from: Lupin III. on July 12, 2022, 12:10:49 pmSoftware?

author: AndyBeez
author_rank: Frequent Contributor
timestamp: July 12, 2022, 01:41:52 pm
content: A 1S BMS for a LiFePO4 cell??? Nominal 3V2 not 3V7?[ Already sounded wrong as I typed that ]

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 12, 2022, 01:53:01 pm
content: The simple way is to use one of those one shot timers and experimentally find roughly what time gets it into the ballpark. Or use a smart plug with energy monitoring and program it to turn off when it detects the charger going into the tapering off region.

author: jh15
author_rank: Frequent Contributor
timestamp: July 13, 2022, 03:57:21 am
content: i use this for my phone.https://chargie.org/my laptop now lets you set the bios to a charge limit. nice if it is rarely unplugged.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 13, 2022, 04:08:50 am
content: Quote from: jh15 on July 13, 2022, 03:57:21 amThis app doesn't need the smart switch if it supports your device:https://f-droid.org/en/packages/mattecarra.accapp/
Comparison of hi side gate drive techniques for LLC converter? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 17, 2022, 11:56:34 pm
content: Hi,The attached shows two different ways of doing a hi side gate drive for a 2kW Half Bridge LLC converter with vin=390V.Do you agree that method “A” is better than method “B”, simply because there is more availability of single output , non-complimentary gate drivers? Or do you believe that the “dead time” is worse with method “A”, meaning the gate drive transformer has a longer “non-driven” interval than with method “B”?LTspice sim and jpeg schem attached should you wish

author: uer166
author_rank: Super Contributor
timestamp: June 17, 2022, 11:59:18 pm
content: Seems like a lot of parts and complexity.. If you're using LT gate driver parts anyway, why not just ditch the GTDs and use proper digital isolators, or isolated gate drivers + small DCDC supply? It's way more repeatable, accurate, and deterministic than gate drive transformers with 20 passives around them.

author: Faringdon
author_rank: Super Contributor
timestamp: June 18, 2022, 11:53:11 am
content: QuoteThanks, ...we will be using TC4428 or TC1428 gate drivers in the real thing.....which have the same format as the LT ones above.
Floating heatsink on diode connected to switching node. - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 17, 2022, 10:11:33 am
content: Hi,My 2kW offline SMPS PCB uses the SK9525STSTO220 heatsink for an anti-parallel sic diode in the LLC stage.The idea was to solder it to PCB local ground to reduce noise.But the solder tabbed version is not available......just the no_solder_tab one...so i will have to use that. This Diode is connected to the switching node of the LLC.......meaning much noise.......i will now have to leave the heatsink floating....do you foresee problems?.....in the past i always anchor these down to local ground.SK9525STSTO220https://www.fischerelektronik.de/web_fischer/en_GB/heatsinks/A04/Extruded%20heatsinks%20for%20PCB%20mounting/VA/SK9525STSTO220/index.xhtml

author: trobbins
author_rank: Frequent Contributor
timestamp: June 17, 2022, 12:30:44 pm
content: You may be able to get a heatsink insulator pad with embedded metal shield - I recall Bergquist used to make them. Or make something equivalent yourself.

author: Jeroen3
author_rank: Super Contributor
timestamp: June 17, 2022, 02:29:46 pm
content: Connect the heatsink to ground with an x-cap to prevent it being an antenna.

author: Faringdon
author_rank: Super Contributor
timestamp: June 17, 2022, 08:22:51 pm
content: Thanks, otherwise do you think that the noise will make the controller malfunction?

author: Jeroen3
author_rank: Super Contributor
timestamp: June 17, 2022, 08:33:43 pm
content: No, but you might fail emission testing.
What to connect offline PSU mains diode bridge heatsink to? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 09, 2022, 08:06:06 pm
content: Doing PFC’d HB LLC of 2kW.Have connected all heatsinks to their local ground. ..since they are heatsinking semiconductors with switching nodes on them. But the heatsinks for the diodes of the mains diode bridge……they are slow switching…so can we just leave those heatsinks floating?Heatinsk is double GBJ5010http://www.jgdsemi.com/files/jgd/all-products/pdf/1-Bridge-Rectifier/GBJ5001-GBJ5010-GBJ.pdf

author: bob91343
author_rank: Super Contributor
timestamp: June 09, 2022, 10:27:33 pm
content: I don't see any specs regarding speed for this bridge. I wouldn't use it in switch mode circuits. Find a bridge that has a switching time specification.

author: trobbins
author_rank: Frequent Contributor
timestamp: June 09, 2022, 11:35:10 pm
content: bob91343, if the topology is simple cap filtered bridge in to a boost then the bridge is only switching mains frequency - but that said, a faster diode may have some benefit but that would need to be confirmed.The bridge internals will have some minor parasitic capacitance to a heatsink, so perhaps better to allow the heatsink to be locally linked to following bulk capacitor or incoming neutral or PE for emc testing options.
No  open feedback loop protection in PFC controller UCC28070A? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 05, 2022, 06:30:48 pm
content: Hi,Would you agree, if an upper output divider resistor in UCC28070A based Boost PFC circuit is absent, then output will just get severely overvoltaged?UCC28070A datasheet.https://www.ti.com/lit/ds/symlink/ucc28070a.pdf?ts=1654447500069&ref_url=https%253A%252F%252Fwww.bing.com%252F