hybridfree/eevblog-posts huggingface dataset:
3 phase BLDC fan is in discontinuous mode? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: September 27, 2023, 07:00:12 pm
content: Hi,Attached are VDS voltages for the bottom three fets of a 3 phase BLDC fan drive at 80W, 24Vin. Time base is 500us.Would you say the coil currents are in deep discontinuous mode?BLDC drive chip is MC33035
Another Tesla big battery on fire - Page 1
Forum section: electronics / general

author: .RC.
author_rank: Frequent Contributor
timestamp: September 26, 2023, 08:26:05 pm
content: A fire has broken out at the Tesla battery bank in my part of the world. Recently installed.https://www.pv-magazine-australia.com/2023/06/28/genexs-energises-its-100-mwh-bouldercombe-battery-in-queensland/https://mypolice.qld.gov.au/rockhampton/2023/09/27/fire-hazard-bouldercombe/Quote

author: trobbins
author_rank: Frequent Contributor
timestamp: September 27, 2023, 01:46:39 am
content: Still going through the last phases of commissioning it seems. Oz seems to be the place to uncover gremlins related to commissioning. The geelong site showed up some install issues, so hopefully this latest fire finds and rectifies a few more.https://www.abc.net.au/news/2023-09-27/tesla-battery-fire-at-queensland-renewable-energy-project/102905302

author: Marco
author_rank: Super Contributor
timestamp: September 27, 2023, 01:58:07 am
content: Still think semi-watertight enclosures and some sprinklers make sense.

author: .RC.
author_rank: Frequent Contributor
timestamp: September 27, 2023, 02:04:48 am
content: LOL at the renew economy take on the issue.https://reneweconomy.com.au/fire-erupts-in-tesla-megapack-battery-module-at-bouldercombe-storage-facility/"Fires in fossil fuel facilities – including petrol stations, coal fired power stations and gas facilities – are more common."Well strike me roan, there are fires at coal fired power stations, places there are gas, like households with gas cookers and petrol and diesel cars have fires inside them as well. Bloody hell.
High Speed IGBT - Page 1
Forum section: electronics / general

author: geggi1
author_rank: Frequent Contributor
timestamp: September 13, 2023, 06:08:32 pm
content: HiIm working on an application that require high speed IGBT.The switching time between ON and OFF must be better than 10mS.Voltage rating higher than 300V and current tating of at least 2000A.Can somebody give me a reccomandation for IGBT with these spesifications or better.I know that silicone carbide devices are the new and hot stuff for high performance devices would this be a better solution?

author: ahbushnell
author_rank: Frequent Contributor
timestamp: September 13, 2023, 07:06:05 pm
content: 10 ms is very slow. Did you mean microseconds?

author: ahbushnell
author_rank: Frequent Contributor
timestamp: September 13, 2023, 07:09:50 pm
content: Infineon makes high current IGBT's. How fast will your system switch. i.e. pulses per second or is it DC.https://www.infineon.com/cms/en/product/power/igbt/igbt-modules/one device.https://www.infineon.com/cms/en/product/power/igbt/igbt-modules/fz3600r17hp4_b2/SiC are much faster and more expensive.Andy

author: Marco
author_rank: Super Contributor
timestamp: September 13, 2023, 07:47:10 pm
content: Quote from: geggi1 on September 13, 2023, 06:08:32 pmContinuous? If so it's going to be a bit expensive.

author: geggi1
author_rank: Frequent Contributor
timestamp: September 13, 2023, 09:54:20 pm
content: My client got the money.Its a H-bridge with at least one set of spares.
How does one set up a safe HV power electronics lab ? - Page 1
Forum section: electronics / general

author: LinuxGuy123
author_rank: Regular Contributor
timestamp: October 01, 2023, 01:18:57 am
content: I need to do a bunch of design and testing on some 800V power conversion equipment. I'll be working at the circuit board level.I need to set up a lab in which to safely do this work. I need to write an employee handbook on how to safely do this work.Where do I start ? What advice do you have for me ?Thanks

author: f4eru
author_rank: Super Contributor
timestamp: October 01, 2023, 08:37:53 am
content: 2 ways to do IMHO:1) write simple concise rules with a few precautions, that are probably not enough to cover all cases, but help to get you covered.2) write extensive rules that nobody will follow.In all cases :- get first help training for all people, and equipment ready (defib, eye wash, ....)- don't be shy to put enough protections (emergancy cutoffs, 30mA differential, gloves, googles, protected bananas....)- put a medical examination mandatory for every electrisation, however light.- always require 2 persons present to do work.

author: mzzj
author_rank: Super Contributor
timestamp: October 01, 2023, 02:46:16 pm
content: Closer to 100W or 100kW power level?800V voltage level might point to latter and creates it's own problems. You need to start thinking of arc/blast shields, hearing protection, test chambers etc.

author: nctnico
author_rank: Super Contributor
timestamp: October 01, 2023, 03:10:21 pm
content: Quote from: LinuxGuy123 on October 01, 2023, 01:18:57 amWhere to start? At the endI assume your product will need to be certified at some point. I'd start with calling a company that does the certifications and ask them how they deal with safety. Maybe ask for a tour at their facility. That should result in some pointers and maybe referrals to experts you can hire to setup your own lab. Maybe even provide training for the workforce that needs to deal with testing.

author: Bud
author_rank: Super Contributor
timestamp: October 01, 2023, 03:29:01 pm
content: This is liability risk. I would offload the risk and at least hire a short term electrical health and safety contractor to set up the environment, do training, guides and stuff.

author: jonpaul
author_rank: Super Contributor
timestamp: October 02, 2023, 05:39:22 am
content: Bonjour a tous: 800V at what power thruput level?Power electronics is a specalty, mistakes in design, protos, magnetics and test technique can damage the DUT, test equipment and the technician or engineer.800 V IS LETHAL.It takes many years of experience and study to develop the skills needed for effective design, magnetic design, propt and debugging of power electronics.Afterwards, compliance for EMI, safety, reliability are a long process are requires specal equipment.Depending on the applications and funds avail, consider to hire a lab or consultant with prooven track record in the field.Just the ramblings of any old EE (56 years experience)JonPS: IEEE PELS:https://www.ieee-pels.org/
Creepage and clearance in offline SMPS? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: September 06, 2023, 08:43:39 pm
content: Hi,Does anyone have the copies of the standards EN60010 and EN62368, which detail the clearance and creepage distances for EU Offline SMPS's?I believe they changed recently?.....pri-sec is now 8mm?Also, within the primary side.....flyback drain to Primary ground is 1.5mm?(Where flyback drain goes up to 700Vpk).Why is IPC2221A a free download but EN60010 and EN62368 are not?

author: Gyro
author_rank: Super Contributor
timestamp: September 06, 2023, 08:51:46 pm
content: Oh FFS, do you really claim to be an SMPS engineer? You're just taking the piss now!

author: tom66
author_rank: Super Contributor
timestamp: September 06, 2023, 09:14:02 pm
content: You can get cheap copies of standards documents from Estonia, a member of the EU so with full access to EN standards. Legal and with no question that they are up to date. Sharing copyrighted standards documents here is a no go.https://www.evs.ee/en/evs-en-61010-1-2010-a1-2019Half an hour's pay, if not even less, for a good engineer - I'm sure you (or your employer) can afford it.

author: tggzzz
author_rank: Super Contributor
timestamp: September 06, 2023, 10:41:25 pm
content: Quote from: Faringdon on September 06, 2023, 08:43:39 pmAny professional engineer would have access to such documents, since they are a necessary prerequisite to producing a professional product.Only amateurs wouldn't have access.

author: Faringdon
author_rank: Super Contributor
timestamp: September 07, 2023, 05:53:21 am
content: OK thanks, though i am novice level. Think Norris the novice.

author: tggzzz
author_rank: Super Contributor
timestamp: September 07, 2023, 07:31:20 am
content: Quote from: Faringdon on September 07, 2023, 05:53:21 amReally?Most people here are under the impression that treez/ocset/faringdon has been professionally involved with SMPSs for decades, and has had 30+ jobs.Which bits of that are true and false?

author: Gyro
author_rank: Super Contributor
timestamp: September 07, 2023, 07:58:29 am
content: 20 years and 42 jobs to be more accurate. The self-characterisation would explain a lot though!
24V 350W Motor Using Parallel 18V Tool Batteries - Page 1
Forum section: electronics / general

author: WaldPinkler
author_rank: Contributor
timestamp: August 29, 2023, 11:41:59 pm
content: Hello everyone,I'm currently working on a project where I need to design a device to power a 24V, 350W motor using 18V tool batteries. The 18V output from a single battery is sufficient in terms of voltage, but unfortunately, it doesn't provide enough current to power the motor. Therefore, I'm considering using two 18V batteries in parallel to meet the current requirements.The challenge I'm facing is how to safely parallel these batteries without running into issues like one battery discharging into the other. I've considered a few options:Diodes: Adding diodes to each battery line could work, but this approach generates a lot of heat and would require large heatsinks, which is not ideal and one battery takes the load if the voltage is different between them.Ideal Diodes: These create an OR-ing condition. Some have a sharing condition if the voltages are close enough.Powermuxes: Just a switching mechanism between sources.I've also thought about more complex and potentially expensive solutions like using two stackable boost converters. Another idea was to connect a buck/boost converter to one battery, with a load sharing IC that could sense the other battery and match its output. However, these options seem overly complicated for what I'm trying to achieve.I would greatly appreciate any insights or suggestions on how to tackle this problem effectively. Are there any simpler or more efficient methods to safely parallel two 18V batteries for my application?Thank you in advance for your valuable input!

author: temperance
author_rank: Super Contributor
timestamp: September 04, 2023, 08:50:46 am
content: Do you really have to use those power tool battery packs?

author: f4eru
author_rank: Super Contributor
timestamp: September 04, 2023, 07:08:36 pm
content: Yep. Many risks associated.Avoid it.
Making a Delta 3 phase supply - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 15, 2023, 07:11:28 pm
content: Hi,Is there anything wrong in this method of producing a Delta three phase supply to a load?It just uses a Y 3 phase supply, and then uses three separate isolation transformers with secondaries connected in delta.There is also a 3 phase variac interposed between the Y supply and the isolation transformer primarys, but not shown.LTspice and jpeg attached.

author: jpyeron
author_rank: Regular Contributor
timestamp: August 20, 2023, 12:52:35 pm
content: Too much to analyze - are the specifications or design parameters to validate against? In other words, what are you suspecting is the issue.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: August 20, 2023, 08:09:46 pm
content: It should work.

author: TimFox
author_rank: Super Contributor
timestamp: August 20, 2023, 08:25:00 pm
content: When last I looked at this problem, a single three-phase core transformer used less iron than three single-phase transformers for the same kVA.

author: Claude
author_rank: Newbie
timestamp: August 22, 2023, 10:59:50 am
content: make some analysis with 3th harmonics... I somewhat remember that Y coupling is bad on this (can make huge current on neutral), thus better to have secondary (at least) with triangle (delta) connections.EDIT: well, I shall have given it a better look, that what you have done. I also see that I'm confused with english Y and delta labels (now corrected)... still need to make an analysis to check what happend with harmonic 3.
MegaVARs at your fingertips! - Page 1
Forum section: electronics / general

author: AlbertL
author_rank: Regular Contributor
timestamp: August 21, 2023, 11:35:44 am
content: This is the first time I've seen the actual user interface for adjusting reactive power generation:

author: jonpaul
author_rank: Super Contributor
timestamp: August 21, 2023, 01:42:07 pm
content: The utilitys have automatic controls nowadays, with MW, MVAR, PF monitors and limits and useCapacitor banksSynchronous CapacitorsSynthetic capacitorsj

author: AlbertL
author_rank: Regular Contributor
timestamp: August 21, 2023, 02:37:31 pm
content: Quote from: jonpaul on August 21, 2023, 01:42:07 pmYes, I think that's how it's done in the transmission and distribution parts of the system, but at the generation end there's still some manual control under the direction of a load dispatcher.My utility seems to use mostly fixed capacitor banks for PF control on the distribution system. The cap banks are manually opened/closed via fused cutouts. I think the idea is that the caps will be connected when summer arrives and air-conditioning motor loads pull down the PF, but I'm not sure that anyone ever does that. One or two of the fuses on any given bank are always blown
NCP1340B4 QR Flyback qu's - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 20, 2023, 06:28:34 pm
content: Hi,***Can you use just one Brownout diode with NCP1340B4 ?...NCP1340B4 has 2 diodes connected (OR'd) from the AC points of the bridge, to the HV pin...which then does...1...startup2...brownout detection3...Recovery from brownout4...X2 cap discharge.We dont care about X2 cap discharge...But want brownout and "Recovery from brownout", and HV startup.So can we use just one diode here?the datasheet doesnt make it clear.....it implys that one diode would be ok for brownout detection...but does not make it clear that recovery from brownout, or startup, would be possible with just one diode?***Why does V(ZCD pin) need to be at least 8V when the secondary is conducting?, ..as said by page 15 of the NCP1340B4 datasheetEven with high leakage current, there is no chance that even if V(ZCD pin) was only 5V, that the ZCD pin would ring below 80mV (The ZCD comparator threshold).So why minimum of 8V?NCP1340B4https://www.onsemi.com/products/power-management/acdc-power-conversion/offline-controllers/ncp1340
multi input buck-boost system questions  - Page 1
Forum section: electronics / general

author: Sniper1
author_rank: Regular Contributor
timestamp: August 16, 2023, 06:29:10 pm
content: So here is my scenario:I have multiple Li ion cells in parallel, each with a buck boost (bidirectional) + INA219 for current and voltage measurement , each SMPS is tuned by a DAC so i have programmable 3-5Vall cells are separated by FETs , i also have a common rail for 5V in and another one for DC out.I know how to charge the cells in CC CV mode but the discharge part is the problem for me.How can i discharge more then 1 cell at .5A ( or wherever) into the output buss?In my mind it seems doable since P=UI where U is set by the cell and I by me so P is limited in a way (this is for the input side of the SMPS)As for the output it is again P=UI and P= delta P , here i somehow need to make all SMPS output the desired Power (since i need to have a set U, probably 4.5-5v since I need it to be higher then cell voltage in order for the IC to allow reverse current flow and this is a feature and not a hack since TI itself made a app note about this, for super caps), since P is tied to the other side then the only thing i can adjust is the current aka my load.Note: yea there are loses and perfect .5A is not that importantAnd yes i am very careful with Li ion cells since i know that they are dangerous, that is why i am playing at low currents and only with 1 cell as of nowAm i on the right track? Or am i overthinking stuff and there is a much simpler way ?

author: mtwieg
author_rank: Frequent Contributor
timestamp: August 18, 2023, 12:44:55 pm
content: Some more background might be helpful. Sounds like a lot of complexity if you just want to store electrical power, as opposed to an off the shelf battery pack with cells in series. Perhaps your intent is to make it so you can swap cells in and out arbitrarily?

author: Sniper1
author_rank: Regular Contributor
timestamp: August 18, 2023, 04:38:15 pm
content: here is more context:it is a 3 step process :1 charge n cells in parallel from a 5V DC source (do it at CC CV and program that to be a code variable) charge ends at 4.2V or 3.6V ( also code select able for individual cells) more or less done , cell start at a random charge level and some will be bad2 discharge them at .5A CC and measure the discharge curve ( and compute Ah) this is the step that is related to my post, i need to discharge m cells in parallel where m<=n , my output is a common DC bus and at the end of that buss i am also designing the load ( that will be another DC DC hopefuly).3 repeat step 1, but now all cells are at about 3V
Earthing and Y caps on comms board with SMPS - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 20, 2023, 08:21:41 am
content: Hi,Do you agree, that the attached shows where the Y capacitors must be connected/placed in order to improve EMC on this comms board, which has an offline SMPS on it?Do you also agree, that the position of the Earth screw is totally wrong?….and creates a big “high frequency AC” Earth loop? The Earth screw should actually be as close to the incoming mains earth wire as possible.In any case, we are not at liberty to move the earth screw now anyway.Ayk, the position of the Y caps is purely to provide a low impedance path for emissions to remain in the Line_to_Neutral loop. (ie, instead of radiating away to the surrounding earth) The Y capacitors simply “invite” high frequency emissions to come back out of the earthed enclosure, and go back down the Line/Neutral. Any other connection of the three shown Y capacitors would be less optimal, would you agree?
The voltage VBAT on the HP4059 IC - Page 1
Forum section: electronics / general

author: maximzakharov89
author_rank: Newbie
timestamp: August 18, 2023, 12:08:53 pm
content: I am using the HP4059https://datasheet.lcsc.com/lcsc/2301111830_HYPWR-HP4059D6-44Y_C5160406.pdfcharger to charge a 35 mAh battery. Here is my schematic:https://drive.google.com/file/d/1V6T5tnO9MRXfb-wICyKvpw7_hVcmcFzC/view?usp=share_linkI have placed a 3 kΩ resistor R1 (charging current of 33.3 mA). If there is no load on VBAT, everything works fine, and the VBAT voltage is 4.2 V. However, if I connect a load to VBAT < 850 Ω, the VBAT voltage drops to 1.6 V. If I reduce the R1 resistance to 2.1 kΩ, the situation is corrected (VBAT voltage of 4.2 V), but I cannot use this resistor as I am afraid of damaging the battery since the charging current will become 47 mA. What can I try to fix the situation?
Using EV main battery to power inverter - Page 1
Forum section: electronics / general

author: Jester
author_rank: Frequent Contributor
timestamp: July 30, 2023, 06:42:51 pm
content: I'm really out of the loop on this topic. Neighbour tells me he plans to power a Schneider inverter from his new Leaf as a backup power source for his home.Can this be done?Any info or relevant links?

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 01, 2023, 02:02:37 am
content: http://priups.com/riddle/answer-1.htm
Dc step up - Page 1
Forum section: electronics / general

author: Jake8
author_rank: Newbie
timestamp: August 17, 2023, 08:43:35 pm
content: Hi forum,A Friend of mine gave me a 3000watt 230VAC (Growatt SPF3000) island inverter with a lion 4kwh battery. I mounted this set into my rv.This inverter has 2 mppt inputs. To one of these inputs i connected 4pc 420wp solar panelsand on the other input i try to connect the rv's alternator who can supply 14VDC/120A so that the battery charges whils driving even if there is no sunlight.The mppt requires a 75voc to start (datasheet says 65v but i think that is 65vcc) Now i am trying to boost up the 14vdc alternator voltage to 75vdc in order to feed the mppt with 5amps/375watt, this will draw 30amps at the dc step up IN. Offcourse i dont want to blow up the dc step up's capacitors due to time constant mppt v/s capacitors and also the mosfets becouse of the high current draw.But maybe i see it wrong and there is a better solution. I was thinking about 2 dc step ups wired parallel to curb the currents.
Power Integrations Flyback....Feedback Loop calculation - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: July 15, 2023, 05:12:49 pm
content: Hi,I did the attached TOPswitch-HX Flyback design in PI Expert.I then used the equations given by Power Integrations in AN-57 to calculate the crossover frequency, gain and phase margins.However, the equations given in AN-57 give nonsense Bode Plots (as attached in Excel)AN-57:https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjfwabJmJGAAxUhV0EAHWp1BLkQFnoECBsQAQ&url=https%3A%2F%2Fwww.power.co…Do you know how to calculate the feedback loop for this TOPswitch-HX design?It is Offline Universal flyback 24vout and 800mA out.As you know, Only Power Integrations know what controller gains they have put in their chips, so we are dependent on their equations.
Q Factor for offline CCM Voltage mode flyback - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: July 17, 2023, 06:49:19 pm
content: Hi,In AN57, Power integrations say we must take Q = "0.15 to 0.3", when calculating the power stage transfer function.(as part of feedback loop analysis)However, TN-203 by Microsemi.com, on page 8, points out that the Q factor is by w0/Q = R/LEwhereLE = the effective inductance.The microsemi one takes into account that its the load that is damping the Output LC....so it must be correct.Where are Power integrations getting "0.15 to 0.3 from?

author: mtwieg
author_rank: Frequent Contributor
timestamp: July 18, 2023, 01:09:06 pm
content: Quote from: Faringdon on July 17, 2023, 06:49:19 pmI can't find a coherent definition of Q in either document. And I wouldn't assume both would define it the same way, and therefore wouldn't expect them to suggest similar values...QuoteI don't see this, do you expect everyone to read these things top to bottom for you? And relying on the load for damping is very poor practice IMO.QuoteImpossible to say without a coherent definition of Q. That app note shows an additional LC filter on the output of the flyback, so assigning a single Q value to the entire thing doesn't seem reasonable.
PSU is it safe to connect earth / RTN / GND all together? - Page 1
Forum section: electronics / general

author: olc
author_rank: Newbie
timestamp: July 23, 2023, 09:19:02 pm
content: Hi -I am designing a connection board PCB for a 48V High Power Power Supply unit (EMERSON HPS3000-9). I wondered if it is safe, and recommended, to connect the AC Earth, the 48V RTN and the GND all together.Thanks in anticipation for your advices!Olivier

author: Mario87
author_rank: Frequent Contributor
timestamp: July 23, 2023, 09:51:42 pm
content: I don't see anything inherently wrong with doing that, it just means your supply rails will not be floating and will all be with earth referenced.

author: Phoenix
author_rank: Frequent Contributor
timestamp: July 23, 2023, 10:28:50 pm
content: Quote from: olc on July 23, 2023, 09:19:02 pmYes.Quote100% depends on the application. How are you using it?

author: olc
author_rank: Newbie
timestamp: July 24, 2023, 06:36:11 am
content: Quote from: olc on July 23, 2023, 09:19:02 pmIt is for an LDMOS HF Power Amplifier. Chassis/shield is usually the electrical ground reference in such applications, but my PSU has all of its exposed conductive parts floating and I was not sure to be in good practices connecting them together.Thanks for your help.

author: Faringdon
author_rank: Super Contributor
timestamp: July 28, 2023, 07:24:02 pm
content: overall outer chassis, if metal, should be direct connected to mains earth.The + and - outputs of the 48v psu should not float w.r.t. the outer chassis....so either direct connect "-ve" output to chassis, or connect it via a y capacitor to chassis....preferably in just one place.I beleieve you will screw the metal case of the psu to the overall outer metal chassis...so they will both be earthed.If a PSU PCB floats with respect to its outer metal chassis, then it will be a victim of noise, and may well not work....you must either direct connect one of the PCBs "quiet" nodes to the metal chassis...either directly or by a Y capacitor......or else...the PCB will very likely get overwhelmed by noise.
Diagnose faults in IPM FSBB30CH60C  3 H bridge IGBT - Page 1
Forum section: electronics / general

author: JoeyG
author_rank: Regular Contributor
timestamp: June 30, 2023, 10:10:38 am
content: Hi ,I'm looking for experience and suggestions to diagnose a suspect 3 phase IGBT H bridge moduleFSBB30CH60Chttps://au.mouser.com/datasheet/2/308/1/FSBB30CH60C_D-2314295.pdfEg IGBT's shorted or open or other tests

author: ahbushnell
author_rank: Frequent Contributor
timestamp: June 30, 2023, 04:00:12 pm
content: The short should be easy with an ohm meter.
Best way to disconnect floating 144-200V DC from charger? - Page 1
Forum section: electronics / general

author: vv_eev
author_rank: Contributor
timestamp: June 20, 2023, 02:15:59 am
content: I know many people have done this, but I can't seem to find an example. I have another project involving charging a 144 (nominal) up to 190V (actual, call it 200V for design) battery bank that can discharge on the order of 10kW. The charger can be set from 250 to 500 mA, runs on 120VAC mains, and I'd like to switch it using 3v3 from a microcontroller. The charger will have earth ground, but the battery "ground" must be floating to prevent certain faults. I'm thinking the MCU should be on the grounded side.I'm planning on switching the 120VAC live wire with a relay. What's the best way to switch both the positive and negative sides of the battery? How can we prevent back-feeding in the event of the switch failing closed? I think a redundancy in that failsafe is a good idea given the catastrophic potential of failure.Is a very low leakage diode on each of the bat +/- enough? If not, how would you switch it, and would a diode or 2 be a good failsafe?Thanks in advance!

author: uer166
author_rank: Super Contributor
timestamp: June 20, 2023, 06:54:50 am
content: Quote from: vv_eev on June 20, 2023, 02:15:59 amYou shouldn't need to do this if it's a battery charger, switching off AC is sufficient if you don't want to charge the battery. If you really need, you can use some DC-rated relays, with fuses near battery to protect wiring and charger faults. Breaking 500mA at 200V should be straightforward, I've used up to 10A/500V DC relays with a magnetic arc quench.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 20, 2023, 01:27:58 pm
content: I assume the battery already has a means of disconnect? I would make use of that. On the AC side, just use a contactor, very cheap and reliable.

author: vv_eev
author_rank: Contributor
timestamp: June 20, 2023, 10:18:08 pm
content: Quote from: uer166 on June 20, 2023, 06:54:50 amIt's part of a larger system. It trips fault codes if used without disconnecting the DC side of the charger.Quote from: NiHaoMike on June 20, 2023, 01:27:58 pmThere is no battery disconnect. It's permanently connected to its system and will remain permanently connected to the DC side of the charger, aside from any switching I implement, which I have to (see above).
Parts failed, LTM4620AEY, 19pcs out of the 120pcs are failing - Page 1
Forum section: electronics / general

author: Linna
author_rank: Newbie
timestamp: April 20, 2023, 11:45:59 am
content: We used 120PCS on board, but 19PCS failed, pics attached. Anyone knows what caused this failure? Any suggestions to debug on the board?Measurement : VCC_3V3_OUT TO DCOMFail :0.2 ohmGood :560 ohmPerform 2DX & 5DX found no abnormality.

author: vv_eev
author_rank: Contributor
timestamp: June 20, 2023, 02:21:09 am
content: That's a high failure rate. From what source?There are so many counterfeit, used, and failed production chips being sold as new. Outside of a relatively controlled supply chain (like Digikey with exclusion of "marketplace"), there's a good chance of getting bad devices. One thing that happens is a rejected batch being thrown out, sometimes with the numbers scrubbed, but unscrupulous individuals or manufacturers in China will save and sell them, re-etching numbers/logos if they were scrubbed. They also re-label some similar but inferior chips for profit.

author: TimNJ
author_rank: Super Contributor
timestamp: June 20, 2023, 02:36:43 pm
content: Are you using the recommended input/output capacitor manufacturers mentioned in the datasheet? Have you confirmed adequate stability margin for transient load conditions?I have never used one of these -- Seems that they should be pretty bulletproof, but I suppose if it goes unstable, weird things can happen. To me, a high defect rate like that might indicate a marginal design. I'd probably try to test the module by itself, give it the worst case transient load conditions, check if the voltage response waveforms look well controlled or if they are ringing/oscillating.

author: wraper
author_rank: Unknown
timestamp: June 20, 2023, 02:43:07 pm
content: Most likely garbage parts salvaged from e-waste and re-labeled and re-balled.EDIT: Marking looks OK, however relabeling these should be easy because they are labeled with paint. If other modules keep working just fine, most likely it's not a design issue. Also without a schematic, nobody can tell if there us something wrong with it.

author: wraper
author_rank: Unknown
timestamp: June 20, 2023, 02:59:10 pm
content: Quote from: vv_eev on June 20, 2023, 02:21:09 amFinding a real factory reject labelled as a good part is like finding a needle in a haystack. The vast majority of re-labeled components from original manufacturer are simply salvaged from e-waste. One of rare exceptions with actual rejects can be NAND FLASH because factories sell their rejects to third parties at low price as often they can be still useable.
Summer Project::Battery Box Extension - Page 1
Forum section: electronics / general

author: eleguy
author_rank: Regular Contributor
timestamp: June 20, 2023, 12:28:52 pm
content: Everything does not have to be precision(?). Specially not during the summer time. Friend has a rubber boat with a front electric outboard motor. The outboard motor can be wireless controlled. Basic setup had a 100Ah battery somewhat directly connected to the motor. That setup kind of worked but had some limitations like- battery exposed to sea water (yep somehow in the fishing boat it gets everywhere)- cables had to be removed when carrying (heavy!) battery the charging "point"- ugly- ...So, as a "quick" fix I decided to help him a bit and put the battery into the shop battery box. Now the battery was easier to carry (thanks to the handle) and it was somewhat protected from the seawater but the cable removal "issue" remained. Well, (at this point I already realized that feature creeping is close), as a second "quick" fix we installed better cabling with the "caravan connectors". So far all issues were tackled.But, after more annoying issues are gone the less annoying features started to appear. Remote controlled outboard is nice and quiet. So quiet that it is close to impossible to say if it is running at low speed or not. The remote (Minn Kota) controller does not have any leds and it does not say in any way if it even has a battery installed. The motor plays audible tone when command is received but that's all. So, ready voltage / current meter module was installed.Friend was super happy and so excited that bought a sonar and brought the box again back. So, as a n-th fix connector for that was installed. At the same time sonar and outboard motor were placed behind own fused. Just in case outboard gets stuck and eats lots of current. Now even the 2nd fuse tripped the sonar (and some additional future stuff) would remain on. Handy when fishing "between stones".So far here we are but I am certain the box will be still extended. Here are the pics. Not precision (as promised) but works...
Mains Cycle miss heater regulator - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 12, 2023, 08:10:57 pm
content: Hi,We are regulating our 2kW heater by missing occasional mains half cycles. We switch out a half cycle with a triac at the zero crossing.Do you think we will have much problem with Conducted EMC from 150kHz to 1MHz?

author: Gyro
author_rank: Super Contributor
timestamp: June 12, 2023, 09:25:05 pm
content: No, err yes maybe - From previous form, I bet the little SMPS that you are using to power the Triac control circuit is noisy as hell.

author: Circlotron
author_rank: Super Contributor
timestamp: June 13, 2023, 05:37:22 am
content: I think it would be better to skip a whole cycle. Skipping half cycles puts a certain amount of DC current drain on the mains. Your local distribution transformer will not like this, and probably neither will your electricity supply authority.

author: Gyro
author_rank: Super Contributor
timestamp: June 13, 2023, 08:50:20 am
content: Sadly, he has already been told this...https://www.eevblog.com/forum/renewable-energy/which-standard-is-for-dc-current-in-the-mains/

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 13, 2023, 01:55:46 pm
content: How about have the logic only skip a positive half cycle if it had skipped a negative half cycle last time and vice versa? Then there would be no DC average.

author: Circlotron
author_rank: Super Contributor
timestamp: June 13, 2023, 10:50:44 pm
content: Seeing the heater is rated at 2kW, both it and the mass it is heating would have a long thermal time constant compared to a mains half cycle. So provided you aren’t trying to regulated temperature to several decimal points, probably several tens of whole mains cycles could be skipped without any problems.

author: tggzzz
author_rank: Super Contributor
timestamp: June 14, 2023, 07:01:25 am
content: Quote from: Gyro on June 13, 2023, 08:50:20 amThat's good. Now we will only have to put up with a very similar question being askedtwomore times.

author: tggzzz
author_rank: Super Contributor
timestamp: June 14, 2023, 07:09:26 am
content: Quote from: Circlotron on June 13, 2023, 10:50:44 pmI wrote a response to the same effect, and deleted it when I noticed this said the same thing.Given the OP's record over several (re)incarnations, it feels like another example where the OP concentrates (to the point of obsession) on a single treez, while completely ignoring the wood.
Looking for recommendations for power meter to monitor EV charging.  - Page 1
Forum section: electronics / general

author: DougSpindler
author_rank: Super Contributor
timestamp: June 13, 2023, 04:40:23 am
content: I’m looking for a power meter to monitor and measure EV charging. For the one below on Amazon, but wondering if you have a better suggestion. I like this one because in measures kWhrs and has a reset button so I can monitor each charge.I’m also looking for suggestions on how to mount it on a wall.The CT coil cable isn’t quite long enough. Can I just solder on another 15” of wire or will that mess up the calibration?Should the CT wires be twisted or untwisted.Any other suggestions? Thanks.https://www.amazon.com/dp/B0B3WVG2V9?ref=ppx_yo2ov_dt_b_product_details&th=1

author: f4eru
author_rank: Super Contributor
timestamp: June 13, 2023, 05:39:19 am
content: Yep, I used this kind of stuff, it's good for an EV (quasi resistive PF anyway, except for the Zoe)Mods I done :- remove reset button- disable backlight- reduce PSU cap 5x-> reduces consumption to a quarter watt, increases lifetime of PSU components.

author: EEVblog
author_rank: Unknown
timestamp: June 13, 2023, 05:57:42 am
content: Doesn't your EV an/or charger alreayd tell you the charge rate and accumulated capacity?

author: EEVblog
author_rank: Unknown
timestamp: June 13, 2023, 05:59:27 am
content: Quote from: DougSpindler on June 13, 2023, 04:40:23 amI have a 20m long cable from the CT in my fuse box to my Zappi charger. I used CAT5 twisted pair cable. No problems.

author: Jeroen3
author_rank: Super Contributor
timestamp: June 13, 2023, 08:17:46 am
content: Small remark: there is a maximum limit on the amount of additional resistance you can add in CT circuits.eg: myenergi has 100m limit, enphase says stay under 3 Ohm (round-trip).This depends on, for example, the VA rating of the CT and the burden resistor in the measurement device.

author: EEVblog
author_rank: Unknown
timestamp: June 13, 2023, 12:04:53 pm
content: Quote from: Jeroen3 on June 13, 2023, 08:17:46 amYes, at some point you are going to come-a-gutsa. But it usually won't be in the 10's of meters range.

author: DougSpindler
author_rank: Super Contributor
timestamp: June 13, 2023, 03:05:29 pm
content: Quote from: EEVblog on June 13, 2023, 05:57:42 amNo
input current waveform Issue in Totem pole PFC with Synchronous rectification - Page 1
Forum section: electronics / general

author: Pulasthi_P_Perera
author_rank: Newbie
timestamp: June 12, 2023, 07:55:40 pm
content: I am designing a Totem Pole PFC with Synchronous rectification at the slow leg. When is simulate the Topology in the open loop I get undesirable Results for the input Current waveform can someone help me with what is happening?. I used Duty as 0.5 with a 100kHz switching Frequency at the fast leg and a 50Hz 0.5 duty ratio at the slow leg. I Tried changing the Duty ratio switching frequency and phase shift inductor-capacitor values but this error still occurs
Half Bridge Magnetics Integration - Page 1
Forum section: electronics / general

author: hofcake
author_rank: Newbie
timestamp: June 09, 2023, 09:54:53 pm
content: Hello,I have been reading a paper to familiarize myself with the techniques people have used to integrate all the magnetic components in half bridge topologies. I have a design with a half bridge, current doubling topology with a coupled inductor for ripple cancelation and I would like to integrate this into a single core if possible.I found a paper claiming to show an implementation of a current doubling circuit, however, to me, it just looks like an integrated center tap. Am I missing something here? I just see a transformer with a high reluctance leg added to a square core and a winding added to the center tap, imitating the discrete inductor of a center tapped rectifier.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 09, 2023, 10:53:59 pm
content: Turns around the legs are generally going to be counted as half-turns, so they would technically have current doubling in that case. It is something of a "duh" case, as you've noticed. Note also that, to ensure the half turns work correctly, a flux balancing winding is needed around both legs -- which will still give higher leakage than if both windings were around the center (where they can be on top of each other). (They could've made the primary halves in parallel instead.) (Or maybe the three-way choke topology cancels this out and it works fine anyway; I'd have to draw it out, I think.)Tim

author: mtwieg
author_rank: Frequent Contributor
timestamp: June 12, 2023, 12:16:42 pm
content: Could you explain what your objective is in integrating the transformer and choke together? And link to the paper you're referring to?One thing to note about this diagram is that the output current (equal to I1+I2) will cause the core's flux density to be biased away from zero. That means there will be less available flux swing due to primary current before saturation sets in. I'm guessing the small air gap on the center pole doesn't prevent this, but at least encourages the flux from the output current to be distributed more evenly in each leg.
PV production metering on Enphase systems fed by 208V from two phases - Page 1
Forum section: electronics / general

author: AlbertL
author_rank: Regular Contributor
timestamp: June 05, 2023, 06:09:48 am
content: In Washington, DC there are blocks where single-family rowhouses have 120/208V services (two phases and a neutral from a wye-connected transformer secondary). Enphase IQ7Plus microinverters work on these systems, but I see problems with production metering on the IQ Combiner, which measures current via a single CT on the combined output circuit. The power production graph with the "Show Phases" option displays different values for lines L1 and L2. I think it's because the meter is calculating total power as (IL1* |EL1-N|) + (IL1* |EL2-N|), and the 120-degree phase difference between L1-N and L2-N on a wye system (versus 180 on a split phase system) means that the magnitudes of the voltages aren't the same at the instant the measurement is made.I've had a similar problem with Solaredge inverters, and the solution has been to set the inverter grid configuration to "208V No Neutral", which apparently forces the power to be calculated using the L1-L2 voltage instead of the L1-N and L2-N voltages, so the phase angle doesn't matter.

author: Berni
author_rank: Super Contributor
timestamp: June 05, 2023, 06:21:06 am
content: If everything can run on 208V you could just treat L1 as L and L2 as N. That way you get a system where that looks like regular single phase.

author: AlbertL
author_rank: Regular Contributor
timestamp: June 11, 2023, 01:03:36 am
content: Yes, that's what the metering should be doing: simply multiplying the L1-L2 voltage by the current, without regard for the neutral. But apparently the firmware isn't set up that way.
Need Quasi resonant Flyback controller with Max frequency setting? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 19, 2023, 02:36:20 pm
content: Hi,We need to do an Offline 90-265VAC flyback , but the customer needs us to use a certain transformer, which they already bought in high volume...therefore, we need a QR Flyback controller with a maximum frequency setting, so that the switching frequency doesnt go too high when the mains is high.We can only find the NCP1340, and digikey wont let you search on this parameter, does anyone know any others?

author: jpanhalt
author_rank: Super Contributor
timestamp: August 19, 2023, 03:08:19 pm
content: I seem to have found it on DigiKey by entering the number in the search box.https://www.digikey.com/en/products/detail/onsemi/ncp1340a6dr2g/8258551There are several version available. The datasheet, as expected, shows the other versions.EDIT: I misunderstood to what "this" referred.

author: Faringdon
author_rank: Super Contributor
timestamp: August 19, 2023, 03:57:04 pm
content: Thanks, yes, the NCP1340 is the one i found.....but there are no others in that family which have max freq set......and where it is settable, the tolerance is badly huge.......any ideas for one with a low max freq set, and well toleranced.L6566 has QR operation with a settable max frequency, but its a 16 pin chip and we dont have room.Then theres the iW1820, QR with max freq = 72khz...very nice...but no direct output regulation

author: jpanhalt
author_rank: Super Contributor
timestamp: August 19, 2023, 07:21:22 pm
content: That family does have a maximum frequency clap set by a resistor as does the NCP1342.You say the band width is too great (see attachment). What band width is acceptable?

author: Faringdon
author_rank: Super Contributor
timestamp: August 20, 2023, 12:07:00 pm
content: Thanks, the NCP1340B4 FMAX pin bias current is 9 to 11uA.Also, the V(FMAX) must stay below 4V......so keep it below 3.9V for some margin...So then you use a 330K-22K series combo...giving FMAX = 67kHz to 82kHz....bit wider than would like...but maybe we just have to make do, would prefer +/- 5kHzNCP1340https://www.onsemi.com/products/power-management/ac-dc-power-conversion/offline-controllers/ncp1340
Solar system monitor that can be interfaced with easily - Page 1
Forum section: electronics / general

author: Red Squirrel
author_rank: Super Contributor
timestamp: June 09, 2023, 01:43:09 am
content: I want to be able to track solar parameters such as battery voltage, solar input voltage, current etc. While my original idea was to just design this myself with arduino I am wondering if there is a plug and play solution out there? I don't want anything that uses apps or cloud or any of that, but rather outputs data in a format that I can easily interface with it programmatically. Like a web page that just displays it and I can just scrape the data or something. Or even better if it's serial. Goal is to use it with arduino so I can turn relays on/off and do other things based on the information. (ex: turn off certain loads if voltage is too low)Does such a device exist?

author: ahbushnell
author_rank: Frequent Contributor
timestamp: June 10, 2023, 04:42:34 am
content: Try open source home assistant. Lots of video's and info.https://www.home-assistant.io/Andy

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: June 10, 2023, 07:17:38 am
content: Quote from: Red Squirrel on June 09, 2023, 01:43:09 amVictron brand solar chargers have a serial out interface that spews out all the data whilst charging your system. Whilst with the modern chargers, you do need to use a bluetooth something to tweak the charger settings initially and feed it the latest firmware, the serial can be read by an arduino, depending on the particular serial chip on the arduino.Hit me up if you'd like more info.

author: Red Squirrel
author_rank: Super Contributor
timestamp: June 11, 2023, 12:21:08 am
content: Quote from: ahbushnell on June 10, 2023, 04:42:34 amThat's just software I'm looking for hardware. Will probably just write some basic python scripts or something. Basically if voltage goes below a threshold for more than a certain time it will turn off inverter. I'll just use a relay then wire it in to the on/off switch. I already have a charge controller and everything, I just have not actually put it to good use as I don't want to put loads on it and be blind as to what the voltage is. My plan has always been to just design the system myself but looking for off the shelf solutions first so that it's more plug and play. Getting accurate readings can be really tricky as lot of things can affect it such as temperature. The battery voltage reading on my server rack can be off by several volts sometimes, and it's very random. I suppose using resistors in the divider with a lower temp coefficient can be better or a set of two with differing coefficients (ex: one negative one positive). but if I can just buy a monitoring system that handles all that then I'll go that route.The charge controller that is in place is an Epever which has serial... now I wonder how readable that data is, maybe that IS an option. Assuming it actually is serial that is... it uses a phone jack and it's for the display panel, but maybe it just uses it's own protocol too.. will need to play around with it.