Petrol Generator Mod - Inverter AC Output - Page 1
Forum section: electronics / projects

author: WanaGo
author_rank: Regular Contributor
timestamp: January 08, 2019, 03:38:17 am
content: Hello,I am after some assistance in a project I am working on.I got an older 'Silent' Petrol generator, which has a Honda GX120 engine in it, and a 1400W Alternator of sorts, which is 2 pole, and has 220VAC 50Hz and 12VDC 8A outputs.Looking at the outputs on a scope, they are not very pretty at all. The DC doesn't at all look like DC, but when put on a large cap it smooths out nicely.The AC is, well, just yuck. I guess this is just how generators of this era were before the inverter ones came on the market.It works fine when you connect a Drill or Light etc, but I don't suspect it would be very good for more sensitive equipment.The generator does not 'talk' to the motor, its all governer based, and the motor purely runs at a set 'ish' RPM, and the 3000RPM basically translates into 50Hz based on 2 pole - I believe.So what I am planning to do is bypass the current AC outputs, rectify the winding phases directly into DC, and then invert the high voltage DC into a more pure sine wave AC. I guess this is just typical stuff really.The problem I have is most Inverters in the lower price bracket are designed for 12VDC or 24VDC to 220VAC, and not so much for 300+VDC input.I have been scouring Aliexpress and I found these:https://www.aliexpress.com/item/Aiyima-2000W-Modified-Sine-Wave-to-Pure-Sine-Wave-Inveter-Board-Driver-EGS002-AC16VDC380V-to-AC220V/32845887806.htmlhttps://www.aliexpress.com/item/2000W-Pure-Sine-Wave-Inverter-Power-Board-Post-Sine-Wave-Amplifier-Board-DIY-kit/32334756548.htmlhttps://www.aliexpress.com/store/product/Aiyima-2000W-Modified-Sine-Wave-to-Pure-Sine-Wave-Inverter-Inverter-Finished-Board-with-Heat-Sinks/1756394_32847801786.htmlThere are a few others too.These take a 380VDC intput, along with a low voltage AC (which looks to be rectified and regulated into DC) to power the electronics on the board, which I think are 5VDC based, and you get a Modified or Pure Sine Wave AC output.I am basically after some input as to what people think. Do these boards look OK? The descriptions are not the best, but you can kind of get a feel that they are using the same sort of Driver boards on them, but the base boards vary a little.There was also this one, which uses the same Driver board again, but it has some images of them hooking it up in a test situation and a scope:https://www.aliexpress.com/item/2000W-Pure-Sine-Wave-Inverter-Power-Board-Post-Sine-Wave-Amplifier-Board-DIY-kit/32728282834.htmlAm I going about this the right way or is there an easier path?For the 12VDC output of the generator, I plan on just passing this through a switching regulator, to get a stable 13.8V or so out, to charge batteries etc. I might even make the adjustment more accessible so I can turn the output voltage as required for what I end up powering.So the main bit I am stuck on is the AC side and how to clean it up, and if this rectified into DC and inverted with something like the above boards, is the way to go.Any suggestions welcome.Thanks

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2019, 05:37:02 pm
content: If you just want to have a big complicated DIY project to show off your abilities then it could be interesting to try, otherwise you will spend far more effort than it is worth and end up with something that likely doesn't work as well as the cheapest Chinese inverter generators on the market. Those older style generators work fine when noise isn't a problem, the output looks a bit ugly on a scope but I have used one before to power lights, refrigerator, tv, computers, etc without issues. They are still popular unfortunately, on the rare occasions when the power goes out here there are at least a dozen of them roaring away within 20 minutes of the outage. The incessant din is unbearable, I can't hear myself think. This is probably worse here in 60Hz land where conventional generators scream at 3600 RPM.

author: ConKbot
author_rank: Super Contributor
timestamp: January 08, 2019, 06:44:02 pm
content: What do you want to run that's a "sensitive" load? Most computers, and switching power supplies are just going to rectify it to a 340ish volt rail internally, so the benefit of another rectify/invert stage for general use seems dubious.If you must, though, get a 2kw inverter of whatever price point you prefer and get to hacking. I've done a overhaul on a broken 3kw square wave one i picked up for cheap, it's was just a 2 channel push-pull converter to get the +/- DCV rails, and an IGBT H-bridge for the output. If you could externally supply the DC rails and maybe bypass some undervoltage detection circuits if needed, you could probably trick one into working with either external HVDC or 12/24V in.Id suggest not going for an absolute cheapest unit, as I worked on a 2kw unit also, that its MSRP was much cheaper than the 3kw one and it was a ratsnest of wires and PCBs and quite miserable to even disassemble. Vs a single PCB and a couple wires to connectors on the 3KW unit.

author: DrDeke
author_rank: Contributor
timestamp: January 08, 2019, 09:57:47 pm
content: If you're open to a different approach, it might be cheaper (and easier) to buy an old double-conversion UPS and connect it between your existing generator and the load.Here in the US, an old 2 kW double-conversion UPS like a Liebert UPStation GXT or GXT2 can be had for about $100 on eBay. They tolerate being powered from my extremely cheap petrol generator and run on inverter full time to provide a nice output. These particular models don't even seem to need a battery installed to perform this function (although they would obviously lose power immediately in that condition if your generator stops).These exact models won't work for you, they only work on 100-120 V input (unless you get a 10 kW+ unit, which sounds like overkill in your situation), but perhaps you could find something similar that is designed to work with 220 V.

author: DrDeke
author_rank: Contributor
timestamp: January 08, 2019, 11:39:40 pm
content: Quote from: WanaGo on January 08, 2019, 03:38:17 amFor what it's worth, I think the output of a "modified sine wave" inverter will probably be worse for your loads than the original output of the generator would be. (That is, to the extent they would have a problem with the generator's output in the first place.)

author: james_s
author_rank: Super Contributor
timestamp: January 09, 2019, 02:27:58 am
content: Quote from: DrDeke on January 08, 2019, 11:39:40 pmIt definitely will. I have a modified sine wave inverter and it makes transformers buzz badly, and years ago I blew up a cordless drill charger plugging it into one of those. The output of a cheap generator doesn't look very good but it's not as bad as it looks.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 09, 2019, 12:35:09 pm
content: Thanks for the replies everyone.So this unit I have is not a Chinese knockoff, its an Italian made machine (better/worse haha I dont know), it has a genuine Honda GX120 engine in it, and I cant find any branding on the generator alternator side of things.Its quiet, you can have a conversation while standing next to it. I have not yet found a date of manufacture yet, and the Italian company who seems to make it 'Airmax Generator Division, Italy' does not seem to feature on Google, or has closed down. There is a name plate on the side, which is 9402 which could indicate 1994 or 2002 potentially.Under the cover of the alternator it has an 8uF Run Cap for the field I guess, but nothing else on the output stage. The DC side has a single phase bridge rectifier, but no capacitor on its output, so that is nasty looking on the scope too. I guess that is designed to be plugged in to a battery to charge it, or into a device which has decent input filtering. When you put a cap on it unloaded, it stabilises to a more DC looking signal, but does vary somewhat when the RPM deviates a little on the engine. Its actually around 24VDC when unloaded with a cap on it, but comes down with load, much like a transformer I guess. I regulated it down to 13.8V and the output is nice and stable, just when I was testing things.So going back to the AC side, yeah its not very nice, and I can appreciate what has been said. They are what they are, and they do power things I know. I am not wanting to upgrade for any particular reason than to have a project and improve what I have. Yes buying new will get me better I know, but thats not what this is about.I have powered a fan, a drill, some lights etc, and no issues from what I can tell. The output on the scope however is really not great. Here is a bit of a pic of it, in differential mode with math CH1-CH2. I only have 1x/10x probes, so excuse the poor shot.Here is one of the DC, unloaded, without cap.The thing I don't like is the varying frequency. As load comes on and off, the motor RPM changes, and then it reacts and it goes fairly stable again. There is no comms on this unit, no feedback between the generator side and the engine, its just a governer. If you get a bit of crap in the fuel, or it starts running out of fuel or something, the revs change, and the motor might conk out if the fuel runs dry etc, but during that period the frequency is all over the place. My fear is what might happen to 'something' connected to it which is more sensitive.I don't have a particular load in mind, its just something I wanted to bring up and see what people think.When I got the generator the engine had bad blow-by, the carb was totally gummed up, it was leaking oil, and a few other typical maintenances related issues. The insulation under the covers powdered when you touched it. So I honed the cylinder, got a new piston and rings and gasket set, ultrasonic cleaned the carb and rebuilt that, and now it runs brilliantly. Replaced the insulation, and basically gave it a total work over, it was good fun. So I did that last week, and while I had it out I thought I would attempt to get the output to be 'better', and that's when I stumbled on those links from Aliexpress.What I can't make out from the Aliexpress stuff is if they are Modified Sine Wave output, or Pure Sine Wave Output, and if you need any other 'bits' other than the board itself. The links suggest both modified and pure, and then some have some instructions on some sort of modification, but I cant follow what its talking about. There are some cheaper ones, and some more expensive ones. I have just found another one which seems another step up but I have not figured out what the actual difference is yet.https://www.aliexpress.com/item/High-Quality-3000W-Pure-Sine-Wave-Inverter-Power-Board-Post-Sine-Wave-Amplifier-Board-Assembled/32888215704.htmlWould love to know thoughts.Given the generator is 1400W, I imagine if I rectified to DC and inverted back to AC again I am going to lose some capacity. I guess I could have a switch to change between raw output or inverted output, depending what I power off it.This is just a bit of fun and to learn something new, I have never done anything like this and I know little about inverters.Here is a bit of a video of it running just after I put it back together a few days ago.https://streamable.com/t77d3Thanks

author: Zero999
author_rank: Super Contributor
timestamp: January 09, 2019, 01:18:24 pm
content: I can't see of any easy way of doing this. It's going to be a quite complex project.An inverter will boost 12V or whatever to 340VDC, before converting it to 230VAC. It should be possible to modify an inverter to take 340VDC and convert it to 230VAC by bypassing the internal DC:DC converter and using a switched mode power supply to power the 12VDC control board. The 230VAC from the generator could then be rectified and used to power the inverter. The problem is the output from the generator isn't regulated and there'll be lots of ripple, so you'd need a switched mode power supply, rather than a simple rectifier.

author: soldar
author_rank: Super Contributor
timestamp: January 09, 2019, 03:45:28 pm
content: The model is Still 2000Honda made the motorAirmax made the generator and controls.You could probably fit huge low pass filters on the outputs.

author: james_s
author_rank: Super Contributor
timestamp: January 09, 2019, 06:28:30 pm
content: Don't obsess over the small details, just use it, it appears to be working more or less as designed. The varying frequency won't bother anything unless you power electric clocks for extended periods. Did you check the waveform while powering a resistive load?

author: WanaGo
author_rank: Regular Contributor
timestamp: January 09, 2019, 09:03:12 pm
content: Quote from: Zero999 on January 09, 2019, 01:18:24 pmThanks - but did you see the links I posted? These already seem to take the HV DC input, so its just a case of rectifying it, which I already have a 150A 1500V rectifier. The board takes a 15VAC input to power the control board, which is rectifies to DC (you can input 12VDC on many of them too). My thoughts were to rectify the AC from the generator into DC, add some capacitance to smooth it out, and feed it into the inverter board (one of which I linked), and take the 12VDC output of the generator and regulate that and power the inverter controller with that. To me it seems straight forward, but I just have no idea if the boards on Aliexpress do what I think they do.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 09, 2019, 09:05:12 pm
content: Quote from: soldar on January 09, 2019, 03:45:28 pmThats correct, its the STILL2000. This was the only video I could find on the internet of the unit before I brought it.I put a little video of mine running on Streamable,https://streamable.com/t77d3It has a badge on the bottom of the frame too for an Auckland company, who I assume imported and distributed them at some point.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 09, 2019, 09:12:41 pm
content: Quote from: james_s on January 09, 2019, 06:28:30 pmNot sure 'obsess' is what I am doing here. Yes, I could just use it as is, but that's not the purpose of the post.I have only run motors (fans and drills) and lights on it so far, I haven't extended to much else yet. I haven't wanted to put anything I am willing to destroy on it yet. When I did the tests a few days ago, it was after I had read some stories about blowing gear up due to the poor waveforms, so I haven't yet ventured out to powering much more yet. Later today I will try a few other load types and look at the waveform as I do so. The ultimate aim is to be able to run a stick welder or MIG on low settings, on it. The Stick welder I have is a small DC inverter unit, so if that can run directly then that would be great, just not sure if it has the grunt to power it. Will find out soon I guess.The power almost never goes out here, so its purpose in life is not so much for backup power in blackouts, is for using gear away from a power source.

author: DrDeke
author_rank: Contributor
timestamp: January 10, 2019, 02:38:27 am
content: It seems to me like part of your implied question is as follows: "Is it bad/harmful for my appliances to run them on (non-inverter) generator power?"My power does go out somewhat frequently, which has led me to have this same question. I have not been able to find much in the way of good information about this. (I have a very inexpensive non-inverter generator which, at least in some circumstances, does not provide a very clean AC waveform.)I see disclaimers from generator manufacturers, saying that "sensitive equipment" may not be suitable for use with their inexpensive generators, but it's hard to know how much stock to put in that.I see a lot of posts [note: not on eevblog; I mean on other Internet fora] from people who sound relatively uninformed, claiming that cheap-generator power is very bad for all kinds of equipment. Then I read many of those same people claim that a cheap standby or line-interactive UPS will "clean up" such power and make it "safe" for equipment. As far as I can tell this is clearly not the case, which makes me question the claim that cheap-generator power is "bad" for equipment in the first place.I also see a lot of posts from people saying something along the lines of "I have a cheap generator and I always unplug my computers when I have to run it, but I run everything else on it and have never had a problem." This seems encouraging. Even if the generator power damaged one of my computers, the damage would almost certainly be confined to the power supply, and those are easy/cheap enough to replace, so...I have been running almost all of my electrical equipment off the cheap generator when need be, and all I can say is, none of it has broken yet. I don't think my generator is powerful enough to run my central air conditioner but, since those are rather expensive, that is probably the only piece of equipment I wouldn't risk with what I've seen so far.From reading the replies so far to your thread, it seems like people here are somewhat skeptical that the power from your generator is likely to harm your appliances. I would certainly be interested in hearing any additional input people have on this topic; maybe that input would be useful to you, as well.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 10, 2019, 04:51:19 am
content: Spot on, thank you.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 10, 2019, 05:01:26 am
content: The other side of the question is about these Inverters I linked.I got a reply from one of the sellers, who explained they are designed to convert Modified Sine Wave AC into Pure Sine Wave AC.But they appear to do so by rectifying the Modified Sine Wave back into DC again to start with.So this is where my logic of, if they are just inputting essentially HV DC and creating a Pure Sine Wave output, then I could do the same from my generator, rather than doing what its designed for and coming from some sort of Modified Sine Wave device.They then talk about getting 16VAC by wrapping a few turns around the transformer (I assume which is in the first stage in the Modified Sine Wave device) to get this out, then the 16VAC is fed into the board, rectified and filtered into DC and regulated down to 5VDC for the driver board to run off. You can see this on some of the photos, and one of the boards even mark where the DC input can go instead of feeding in 16VAC. So I could feed in DC from the 12V supply of the generator for this.There are a lot of smart people on here, so I was hoping that someone could have a peek and see if they think that logic sounds reasonable from what is shown on the links.Thanks

author: james_s
author_rank: Super Contributor
timestamp: January 10, 2019, 06:01:39 am
content: I have a similar Chinese pure sine inverter board that I use to get 240V 50Hz power over here in 60Hz land. It works ok, however I had to make some modifications to get it to perform adequately, the mosfets and the output filter inductor it came with were crap. It also needs a reasonably well regulated DC voltage input in order to get the correct voltage output.Computers are not particularly sensitive, the modern switchmode power supplies are very robust and they run just fine off cheap generators. The noise and fuel efficiency is crap but I've never had any problems at all running any sort of equipment off old style generators. If I was on a tight budget and wanted an inverter generator and didn't mind using questionable Chinese parts, I'd just buy a Chinese inverter generator, apparently the ones Harbor Freight sells are decent, certainly it's gonna be better than something you could build yourself. Trying to convert a standard generator you wouldn't get the greatly reduced noise and fuel consumption which is the whole reason inverter generators are so much nicer.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 28, 2019, 07:30:30 am
content: Hi James_S,With your inverter, what specifically did you have to change on yours?Was it FET/Transistor related, or something else?To All,I ended up getting an inverter and had it running on the bench, and all looked great really, output was really good etc. I initially tested it at 12V, then 30V then upped it to 200V and then powered it off my generator after rectifying the AC. I put on a small 40W load, everything still good. Then I put on an 850W load from a power tool, and it died. Spun for a moment, then all just went silent. The Generator started kicking like it was under incredible load. The Inverter is rated to 2000W, but I wonder if the surge current has killed a weak component. It was an angle grinder, so I can imagine the inrush is pretty high, but I wouldnt have thought it would have done what it did. The symptoms would suggest one of the transistors has died, to me at least.The inverter has Infineon 47N60C3 transistors, 650V 47A 0.07ohm RDSon (https://www.infineon.com/dgdl/Infineon-SPW47N60C3-DS-v02_06-en.pdf?fileId=db3a304412b407950112b42dff93492f) on it, the large TO 247 package. However I brought the inverter as a kit, so built it myself. Immediate alarm bells when I saw the transistors, as the legs were cut and they had solder on the legs. Looks like its a classic case of recycled materials. Anyway, had no choice so just assembled it anyway and hoped for the best.Wonder if one of those transistors has failed ON and is now basically a dead short and not letting the thing pulse away like it should.The DC input takes 380VDC sort of region and has 2 electrolytic caps on the input. Normally they hold their charge for hours and hours, I tested it the other day about 4 hours later, and the input was still over 250VDC. I will be mounting a 1Mohm resistor across it as a slow drain I think. Anyway, after it stopped working, the input is 0V, so there would seem to be a short circuit. I'll investigate more soon.For another project I had some of these, and still have 3 in my box of parts, same TO 247 package.https://www.infineon.com/dgdl/Infineon-IPW60R041C6-DS-v02_01-en.pdf?fileId=db3a304327b897500127f24dd83c3c09. These ones dont look recycled, but did not come in tubes either. Legs are full length and no solder on the legs.Curious if these would be an appropriate replacement part to use for the dead one, and if I should try swapping one out with one of these. Just not sure if its wise to mix or not. Assuming one is dead of course.I also have 4 of these IGBT's from another project, but unsure if these are any better for this application.https://www.infineon.com/dgdl/irgp4063dpbf.pdf?fileId=5546d462533600a401535655ee0c2450, same TO 247 package again. These sort of look recycled too, tinned legs but they are full length.Never really played with this kind of HV stuff and learning as I go. So please bear with me.Thanks

author: Zero999
author_rank: Super Contributor
timestamp: January 28, 2019, 12:53:05 pm
content: Yes, it was probably the surge which killed it.Why use it on an angle grinder anyway? No doubt it has a universal motor which will be happy with the crappy distorted sine wave from the generator.If you powered the inverter from a rectifier and smoothing capacitor, then the power factor would be poor, which would explain why the generator struggled. Have you checked that it wasn't the rectifier which died?Ideally you need an inverter with a 230VAC input and 230VAC output, with power factor correction.

author: james_s
author_rank: Super Contributor
timestamp: January 28, 2019, 04:39:27 pm
content: My inverter came with counterfeit mosfets of unknown specs which I replaced before building it. Then I found that the output inductor was undersized and would saturate well below the rated load. It was overall not a very good design.

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 28, 2019, 04:40:17 pm
content: As British mountaineer George Mallory's famous quote: "Because it's there", I think I can understand the reasons why some individuals pursue certain goals which appear to be preposterous at first glance.It will be a difficult journey, but if you succeed, you will:Learned many things, both practical and theoretical, that otherwise you would not have learned.Feel really proud of your accomplishments. Also, and this is quite important, your children and grandchildren will also doNow, my two yen on this subject.Power tools most likely utilize series-wound universal motors. They generate very significant amounts of noise, due to the brushes. Additionally and this is most important, they draw very large surge currents.I would advise that you go to E-bay and purchase a bank of power resistors, such that you can do all sorts of troubleshooting without worrying -at first- about your load. Later, you can add in parallel some motor-run capacitors, to simulate a lagging power factor.

author: james_s
author_rank: Super Contributor
timestamp: January 28, 2019, 04:48:10 pm
content: What you really need for any sort of workable solution is very fast current limiting that will both limit the instantaneous current and trip completely if the average current exceeds a safe value for the mosfets.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: January 28, 2019, 05:22:52 pm
content: Take it from one who knows from bitter experience, you're wasting both time and good money.It looks like your generator is an AVRless, self excitation type which probably gives it some immunity to the capacitive loading effect from the PFC and emi filtering used in modern smpsu powered IT kit which sends the more sophisticated AVR type of genset into gross overvolting.For instance, the 8.4μF's worth of capacitive loading on the 230v input of my APC SmartUPS2000 would cause my 230v 2.8KVA genset to generate in excess of 270v which the UPS rejected, removing the capacitance when it switched to the battery, followed by the voltage going back to 230v and the UPS switching back to the generator to start the next yo-yo cycle.A simple self excited (by that 8μF capacitor?) generator is already making use of that overvolting phenomena which should minimise the effect of such capacitive loads that make the more expensive AVRd gensets "unsuitable for use with IT kit" (it's not noisy or badly distorted waveforms or even bad frequency stability that the UPS makers use as an excuse for the problems they cause with such 'cheap gensets' - 30 to 120KVA gensets can't be classed as 'cheap'! - it's this overvolting response to leading current (capacitive) loadings present in most IT kit's PSUs and in the larger amounts to be found in the older line interactive UPSes such as that vintage pure sine wave output (purer than the mains supply!) APC SmartUPS2000 of mine.With regard to your proposed conversion to inverter power, I'm afraid you're not going to see any benefit since what makes the inverter type genset more efficient and noticably quieter on no or quarter/half loadings is the use of a multi-pole (typically 6 or 7 pole pairs on the runner with 18 or 21 pole piece windings on the stator) three phase permanent magnet generator head feeding a full wave 6 diode three phase rectifier to generate the required low ripple 200 or 400 vdc used by the 60 or 50 Hz inverter (basically a pair of back to back high voltage class D amps in H bridge output configuration, driven from the required 50 or 60 Hz reference sine wave generator).Furthermore, a lot of weight and space savings made in these designs is realised from the use of an out runner bolted directly onto the engine shaft to act as a flywheel very much like the arrangement used by the old Seagull outboard motors with magnets embedded into the flywheel as part of the magneto ignition used to spark the two stroke engine. The little 1KW/1.2KW rated Parkside unit mentioned below only weighs a mere 13KG (dry - a full 4.5 litre tank of unleaded adds just under 4Kg to the all up weight).The 18 or 21 pole stator is bolted straight onto the engine casing end to feed the high voltage three phase full wave rectifier integrated into the inverter module which is more than just an inverter, including as it does, a microprocessor to monitor oil level and control the stepper motor driven butterfly throttle on the carburettor to control engine speed to match the electrical demand placed on the PM alternator by the inverter's response to the electric loads plugged into its outlet(s).Basically, I'm advising you to invest your money in an off the shelf inverter genset rather than wasting it on your folly of a project which can only succeed as an educational exercise in "Learning from your mistakes". There are surprisingly cheap inverter gensets available these days (long gone is that accursed Honda monopoly in such kit) but you still need to be wary of the Workzone shite (to name but one).I eventually solved my problem with the original 4 or 5 year old "Backup to my UPS based backup project by purchasing a 1KW continuous / 1.2KW (30 seconds peak) rated Parkside inverter genset (the 2nd generation PGI1200-B2 model) from my local Lidl store for just £99.90 in May last year. This little beauty, as I knew it would, didn't suffer the temperamental voltage effect of the earlier conventional 2.8KVA unit I'd had such a terrible experience of those 4 or 5 years back.I'd have preferred a higher rated inverter genset but these were typically 3 to 5 times the price of the little PGI1200-B2 for just twice, at best, the continuous power output rating. I'd spent the just less than 100 quid basically just to prove that an inverter type genset was THE solution to my problem (I knew the inverter wasn't going to respond with an overvolting reaction to leading current loadings like my previous genset had - the rest, frequency stability and waveform distortion and even "noise" were never ever the issue with my UPS).A few months later, Aldi put their 2000W Workzone inverter gensets on sale at just under 3 times the price so I took a punt on one, discovering just what a pile of excrement these were after sampling three different ones. Believe me, those Workzone units were total rubbish making the Parkside unit a shining example of inverter genset perfection by comparison. Actually, in hindsight, the PGI1200-B2 is inverter genset perfection just on its own merits. The only downside compared to a Honda inverter genset being the 10dB or so higher noise levels but, at a 900 quid saving in purchasing cost, I can happily live with that trivial downside. :-)HTH & HANDJohnny B Good

author: coppercone2
author_rank: Super Contributor
timestamp: January 28, 2019, 06:00:22 pm
content: Lol they make analog cctv malfunction pretty hard. Pc will be fine.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 28, 2019, 07:58:37 pm
content: Quote from: Zero999 on January 28, 2019, 12:53:05 pmThanks for your reply.Angle grinder, as it was at arms length, rated to 850W, thought in my head that I can run up to 2000W and didnt give it much more thought than that.Rectifier didnt die, still OK. I did think that too, but checked it out and all is OK. Its rated to 50A and something like 400A surge.http://www.eicsemi.com/datasheet/KBPC5000_10.pdfthe KBPC5010 version.Disconnect the DC incommer to the inverter, and its still making over 300VDC out of the Rectifier. Connect the inverter again and we have problems.I have no clue what Power Factor really is or PFC, so I need to do some googling. Thanks for your reply.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 28, 2019, 08:01:17 pm
content: Quote from: schmitt trigger on January 28, 2019, 04:40:17 pmYep lesson learned about the angle grinder, it was a poor choice, but I would have come to this position at some point, so better at the very start than when I actually needed to power something.Thanks for the reply. I need to do some more reading on the subject.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 28, 2019, 08:22:08 pm
content: Quote from: Johnny B Good on January 28, 2019, 05:22:52 pmThat's unfortunate. However, that said, my time is free to me and this was a learning exercise more than anything. The inverter itself was not expensive, and the company that sold it to me actually offered it for free if I could make a video on the project after I have it working, but I don't think that's going to happen given the results so far.Quote from: Johnny B Good on January 28, 2019, 05:22:52 pmThat makes sense, damn. I guess this 2 pole generator was never going to cut it. I was naively hoping that rectifying it to DC would remove a number of issues with the limited poles, and then inverting the DC back to AC would then just work. But obviously I have a lot to learn. Which I guess what the whole purpose of this.Quote from: Johnny B Good on January 28, 2019, 05:22:52 pmYep but again that's not the purpose of this at all. I didn't just want to buy something. This isn't something I need to use, it was more of a learning project for me. Buying something teaches me nothing. I was trying to learn from this, and if failing is the way to do that then I guess I am succeeding. It would be nice though to get this working, but from what I am reading I may never get there. I guess I need to do more research on the subject and find out exactly what is going on.As mentioned, I would have assumed that rectifying to DC and then inverting the DC back to AC would have solved limitations with the old generator. Maybe the DC doesnt have enough 'storage' to cope with surge, but maybe the inverter is just too simple to handle surge anyway. Maybe some power resistors would help limit surge current, but is that a good idea? I dont know.This isn't something I want to keep throwing money at, and to date hasn't cost me very much at all, but if there is something more I can do to at least get something out of it, I can convert the generator back to how it was pretty easily, and have the traditional AC output for most things, and have a more limited inverted output for smaller more sensitive loads, then I guess that could be a comprimise. I don't know what the best solution is.I just want to try and understand why this failed more than anything. If its rated to 2000W then in what situation would that actually be viable? A slowly ramping load, rather than anything with surge above this limit?If anyone has any more ideas on what I could try, then I would love to hear.This FPC stuff I really have no idea about, what it is, where it typically is in a system etc or what it does.Thanks All

author: Circlotron
author_rank: Super Contributor
timestamp: January 28, 2019, 09:55:00 pm
content: Somewhat off topic, but it would be cool if someone made a portable inverter generator with 3-phase VVVF output that you could use to drive a 3-phase induction motor.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 28, 2019, 10:42:31 pm
content: Just been googling and came across this youtube video, and just wanted to pick brains on the concept conveyed.So this guy seems to improve PF by using a Run Capacitor on the AC output of the Inverter he has. It seems the Run Cap would change depending on the equipment being run, but I am curious if this concept could be put into practice as a general output capacitor of the inverter to help deliver surge currents to protect the FET's, along with maybe large current limiting power resistors.So off the top of my head, he used something like a 20uF cap for his Freezer, and something like a 90uF cap for his drill press, and it improved the PF considerably.If I was to say put a 25uF run capacitor (which I happen to have one sitting here) on the output of the inverter, would that in theory help deliver current for surge startup on some devices, and help limit the surge loading on the FET's?Obviously it's not perfect as different devices will demand different caps, based on what he showed in the video, but could it help protect the inverter FET's?As what suggested above, power resistors might also help...If I was then to also put say a 5ohm power resistor of suitable sizing on the output of the inverter, before the capacitor (this is likely totally wrong math but say 220V / 40A = 5.5ohm), that might help limit the maximum current pulled out, right?Is this thinking totally wrong, and all I end up making is a basic filter which does nothing useful and I will still blow FET's ?Be niceThanks

author: WanaGo
author_rank: Regular Contributor
timestamp: January 29, 2019, 12:14:53 am
content: More googlinghttps://www.ametherm.com/inrush-current/inverter-inrush-current-protection

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 29, 2019, 01:41:00 am
content: Quote from: WanaGo on January 28, 2019, 08:01:17 pmPlease note.... I made a typo error. Connecting the capacitors in parallel with the resistors will produce a LEADING power factor.If you want to obtain a LAGGING power factor, nothing beats an unloaded induction motor.

author: Circlotron
author_rank: Super Contributor
timestamp: January 29, 2019, 07:56:05 am
content: Quote from: WanaGo on January 28, 2019, 10:42:31 pmFor an induction motor load it would help ~somewhat~ because during the time an IM is running up to speed the power factor is presents is awful. You would need a larger capacitor for runup and a smaller one after it has reached full speed. For brush motor loads like for example an angle grinder, I don't expect a power factor cap is going to help at startup.

author: coppercone2
author_rank: Super Contributor
timestamp: January 29, 2019, 08:16:04 am
content: i got a propane powered generator. Holy shit its a thing of beauty.FUCK gasoline.the things I have gone through because of small gasoline enginesstrip engine at 1am during hurricane. run out of ether. all sorts of BULLSHIT.Do yourself a favor and get a propane compatible one.I need to order a refurbish kit for the old gasoline one. And hopefully never use it again.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 29, 2019, 08:34:21 pm
content: Would having an NTC in series with the output help solve this surge current?Would it help protect the FET's instead of blowing them up if the surge is too high?Do inductive loads like NTC's, or are they a no-no ?Page 1 of this is essentially the circuit I seem to have in the Inverter, however, on mine there is a Toroid on the output stage which is not pictured, with a 0.2uF 375VAC capacitor directly across the output.http://www.lz2gl.com/data/power-inverter-3kw/egs002_manual_en.pdfAny suggestions at all for improving this?One thing I have spotted is bottom right of the schematic, there is a 0.1ohm resistor for the current sense feedback. On mine I don't seem to have this, however there are 2x M shape thick wire bridges which tie from the bottom of the 2 FET's back to the input -ve (GND), so potentially those do act like this. The Chinese comment states 'Kang Copper Wire' so maybe...Would love to hear suggestions for improvement on this thing, if there are any.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: January 29, 2019, 10:20:02 pm
content: The PFC circuit is part of smpsus with ratings above the 75W limit, iirc. It's job in this case is to reduce distortion of the current drawn from the mains supply due to the narrow conduction angle of the basic rectifier and capacitor circuit used to generate the 165 or 330 volts DC supply to the high voltage switching circuit that drives the stepdown and safety isolating transformer in the smpsu. Without such a circuit, the rectifier only draws narrow spikes as the voltage waveform matches then exceeds the charge voltage stored by the smoothing capacitor(s).The PFC circuit draws these current spikes out over a much larger portion of the waveform to mimic the effect of a resistive load, a characteristic also shared by universal motors (albeit with an additional startup surge characteristic- they don't have the narrow conduction angle characteristic of a basic smpsu rectifier and capacitor pack). Induction motors have low PF but at least this is of the ordinary kind were it's essentially just a lagging of the phase of the current relative to the voltage waveform which can be largely corrected for (in the motor circuit) with a simple PFC capacitor.Incidentally, if you're trying to compensate for lagging current loads with additional capacitor across the genset's output, don't try this with the more fancy types that boast "AVR" unless you want to see the output voltage go north of the 140 or 280v mark (120 and 240 volt gensets respectively). You might get away with it using a homebrewed generator based on a suitably rated single phase induction motor using a bank of capacitors to induce excitation in the rotor (after flashing some residual magnetism into it with a 12v car battery before firing it up) but quite frankly any PFC has to be done at each load. There's no one size fits all as that generator capacitor mod implied.The traditional generator only suffers the overvolting effect with capacitive loadings. The inductive loading from motors doesn't create this effect but the excess 'wattless' current still has to be considered from the point of view of avoiding exceeding the generator's maximum current rating. If you run a 1KW motor with a PF of 50% on a 1KW rated generator, although the mechanical load on the genset's engine isn't increased by that factor of two increase in the current draw, you're likely to overheat and possibly burn out the generator windings if such a load is maintained for more than a minute or two at most if the circuit breaker doesn't trip out beforehand.Although the inverter type of genset is free of this troublesome overvolting effect, such additional 'wattless' current of either leading or lagging type still has to be allowed for. Incidentally, the generator inverter modules are surprisingly robust in regard of handling such overloads with the microprocessor providing superior overload shutdown control compared to the simple thermo-electromechanical circuit breakers used in traditional gensets.BTW, I do understand your desire to experiment in the hope of improving the genset and gain some useful experience to increase your understanding of generator technology but I thought it best to let you know what you were up against in this laudable enterprise of yours.Basically, it's a lot more complicated than just simply trying to fullwave rectify and smooth the existing generator's single phase 120 or 240 vac output to provide the necessary high voltage DC to power a 60 or 50 Hz 120 or 240 vac output inverter module. You'll also have to add a stepper motor drive to the carburettor or replace it with a stepper motor controlled one, making the basic mechanical speed governor redundant. If the engine is a four stroke unit, it should already incorporate a low oil level warning float switch which you may need to invert the sense of if you wish to wire it into the inverter/engine management module rather than have it directly disable the ignition to automatically protect the engine from impending loss of lubricant and the risk of seizure.Regarding the comment made by coppercone2 about the use of propane (or, for that matter, natural gas) instead of the ethanol polluted 'gasoline' foisted upon the American nation, I heartily agree with that advice, if only because the use of propane or natural gas removes the need to store quantities of gasoline (petroleum) with a limited shelf life (a year, perhaps two or three with the use of an additive). Also, it eliminates the more corrosive products of gasoline/petroelum combustion, leaving the engine and its lubricant in a much better condition after each run, considerably extending the service life of the engine. What's not to like about a dual or tri fuel genset option?Obviously, preserving the facility of still being able to run off a petroleum based fuel with a dual / tri fuel engine maximises your chances of still being able to run the genset if your supply of propane or natural gas gets cut off - you may still be able to scavenge gasoline/petroleum to ride out any disasters severe enough to curtail those supplies.Here in the UK, the most likely disaster scenario for the majority of the populace will be either a very rare fault induced outage for those in the suburbs, or for those living in the countryside, outages from trees falling onto rural 11KV lines, in both cases, typically a matter of hours, rarely any longer than a day or three.However, the mismanagement by the UK government with regard to investment, particularly of the Nuclear Power station kind, in our National Grid has raised the spectre of rolling blackouts during particularly severe winters. The capacity margin to cover unplanned power station outages is extremely slim indeed, just a matter of a percent or so, afair. Thus far, we haven't experienced severe enough winters in recent years to put the system to the extreme test and it looks like we won't be experiencing one this year.However, it was this possibility in mind that gave me sufficient justification to invest the rather modest £99.90 in that Parkside inverter genset as a backup to my current 2KVA 1500W UPS setup. Initially, I didn't think it would provide for more than just the IT kit alone but the lighting upgrade to LED lamps over recent years has now made it possible to keep both the IT kit (and a TV set or two)andall the lights on through the next electrical outage. Although it's a little too marginal for my liking, it was a surprising result of my renewed assessment of just what this could keep running.The only downside with such cheap inverter gensets is the lack of an electric start option. However, I'm looking to add a bldc controller with, in my case, a 48v dc supply and fast acting isolator relays to use the PMG as a BLDC starter motor, neatly avoiding the need for gross mechanical modifications beyong that of adding a position sensor to provide the necessary "Hall Sensor" commutation signals to my BLDC controller.The sensorless option is only good with well defined mechanical loadings such as pumps or fans and prop blades, hence the need for such enhanced commutation signals. I've proved it will work in principle. With the spark plug removed I see 480rpm using a 48v test battery but even after it has started running just blocking the sparkplug hole with a thumb is all it takes to stall it.Sensorless operation just doesn't cut the mustard in this application. I know exactly how to fix this, I just haven't sprung for the Adapter Board for AS5047P just yet since I need to determine whether the PMG is a 6 or a 7 pole pair outrunner type. I've only recently acquired a 'scope that will let me determine this without the need to physically remove parts just to eyeball the inboard stator coils to get a count (I'm anticipating a count of 18 or 21 such salient poles). This is a project I've put on the back burner for now.What grieves me most about this (lack of) electric starter option in the cheaper inverter gensets (and which also drives my 'electric starter' project) is, well quite frankly, the very lack of such circuitry being integrated into the inverter/engine management modules used in these gensets.In mass production, the extra circuitry would literally only be a matter of a few cent's worth and a square millimetre or two of additional silicon. The more expensive 50vdc converter could be supplied as a luxury add on (a purchase option or after sales upgrade kit ). Even this would only add a few dollars to the BoM costs, far less than that of adding a starter ring gear to the engine and a klunky starter motor and associated mechanicals adding needless extra cost and weight to what is touted as a lightweight suitcase portable inverter genset. The heaviest item being a small starter battery which won't necessarily have to be the obligatory 7AH SLA, it could be replaced with a much lighter and more durable LiPo or L-ion battery pack to keep the weight down to little more than that of the original recoil starter only version.Anyhow, that's the level of my generator improvement project. Starting from where the OP was hoping to end up and finishing with a realisable goal of eliminating the faff of using a recoiling pull cord starting rope.Regards, Johnny B Good

author: WanaGo
author_rank: Regular Contributor
timestamp: January 29, 2019, 11:04:45 pm
content: Thanks JohnnyNot sure how much of that is relevant for me or not.This is a capacitor excited alternator, not AVR. Its a 4HP Honda GX120 engine with governor to control the engine RPM.Running drills and angle grinders directly off the generator before I added the inverter, was no problem, it adjusts fine, no doubt the output blips, but it was hardly noticeable.The aim ideally was to have the inverter also cope fine, and make it work with all loads I might plug in which are within rating.Unsure what the discussion is about sensors, propane and dual fuel, fuel storage, electric starts and controllers etc - none of that seems relevant for what I am trying to get help on. I'm a bit confused with over half of your reply to be honest.I do not want to buy a new generator.I do not need the generator daily.I do not suffer blackouts. I will not be powering the house with this.I don't need propane or dual fuel or anything like that.This is a project.I wanted to try and build this for if I needed remote power when working on something away from the house. Maybe to charge a laptop, power a drill, small welder, small fridge, other power tools, battery chargers, etc. Its not for daily use. Sure, maybe in a natural disaster etc, so I can charge stuff up etc.I wanted to try and put an inverter on it so if I ever had a load I wanted to run off it which was sensitive to rubbish AC outputs, it would work OK.I wanted to try and see if I could make the inverter be as capable as the raw AC output of the alternator was before I started playing with things.I hope its clear what I am trying to do.This is a project I am trying to learn from, to figure out how this stuff works and to tap into knowledge that other people on this forum have that I dont, that might be helpful to what I am trying to do.This is the first inverter I have ever played with, short of a 300W 12V to 220VAC one I have from about 10 years ago which I used in my car.Speaking of which, that has a PTC in series with the phase output...If you are able to help and provide some help, please do share and let me know what I could do or could try.Thank you.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: January 30, 2019, 02:19:45 am
content: Quote from: WanaGo on January 29, 2019, 11:04:45 pmOk WanaGo,I see where your coming from. Sorry for the information overload. I appreciate it's a lot to digest but you can never really have too much info. You can pick out the bits that seem relevant to your project and perhaps refer back to the other, seemingly not so relevant bits as you see fit.One thing I will say is that you'll never be able to match the raw output of your generator with the inverter module since this is yet another conversion stage with its own losses. These class D inverter modules are pretty efficient (circa 95% or better) but in your case, you also have the issue of PFC in the rectifier pack. Rectifying and smoothing a single phase supply voltage needs considerably more filtering compared to the three phase case. If you just slap a BFO capacitor across the bridge rectifier output, you'll be presenting your generator with very high current spikes which it won't take kindly to if you're trying to push for an output from the inverter that matches the original output you were getting directly.Even if you use a third order LPF with a series inductor between two smoothing capacitors to reduce the commutation spikes to reduce the stress on the generator, you're unlikely to do better than 80% of the original rating with such an add on inverter module. However, this might be all you require anyway and you'll have solved the issue of poor quality power for your sensitive electronic kit so there is still merit in what you're trying to achieve. Just don't expect the impossible.Regards, Johnny B Good.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 30, 2019, 02:33:39 am
content: Thanks, thats helpful information.Yes I was never expecting to get the same output power from the inverter as I do from the generator itself, losses were expected. Getting it to work and not blow up is the part I am trying to work around.Even contemplating at this stage to just have the inverter as an option, switch it in and out, using Raw output when required, or Inverted output when required, depending on what i'm powering.So are you suggesting I need to look at doing filtering between the Rectifier and the Inverter input, some sort of 3rd order LPF with Inductor?I still seem to have a problem with this inverter than it has no output protection.Some of the other inverters I see on Aliexpress have a few extra bits, but none of them taken the HV DC input like this one did, so I had to rule them all out.Some of them like this one (when you scroll down the page you see the image) has overload protection, short circuit, under voltage, input over voltage etc. Mine has none of that.https://www.aliexpress.com/item/Free-shipping-1pcs-1800W-5500W-DC12V-24V-36V-48V-to-AC-220V-pure-sine-inverter-board/32637730780.htmlI currently have the 2000W version of this which they sent in error, ordered the 3000W version, which is on its way to me now.https://www.aliexpress.com/store/product/1pc-3000W-Pure-Sine-Wave-Inverter-Power-Board-Post-Sine-Wave-Amplifier-Board/627093_32657842137.htmlas mentioned in a previous messageQuoteSo any suggestions on improvements that could be added on, would be a huge help. I can design a PCB and get it made, and build it etc, I just don't have knowledge of power electronics to this extent to know what is required.Even if I was do to the initial suggestion above and switch inverter in and our depending on what i'm powering, having the inverter protected still seem to be quite an important thing, as if it's so easy to pop with something like an angle grinder, then that's not going to be much chop.Thanks

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 30, 2019, 04:03:56 pm
content: I believe that the AliExpress product will work, if you can make sense of the following Chinglish gibberish:" First, after the correction of the inverter inverter power tube removed, and then look at thecorrection of a few transformers transformer, look at the transformer secondary circuit isconnected in parallel or in series, and then add the transformer parameters, modified wavetransformer secondary is parallel , In each transformer secondary plus 16 laps.The secondary of the modified transformer is a tandem type, plus 8 laps per transformersecondary. Then in the correction transformer which transformer 1 empty foot plus a smallvoltage parameter, the small voltage parameters using 0.6 copper wire, in the transformerinside around: 5 laps, the small voltage is linked AC: 16V position."Just be sure to fuse both the input and the output, and you'll be fine.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 30, 2019, 08:48:37 pm
content: Yeah that chinese detail is a shocker, makes no sense at all.I have a feeling its to do with how normal people would be powering this board. You would get the 16VAC by winding a few laps around the primary transformer which might have otherwise been used to generate power for the 380VDC input.In my case I just have the rectified output out of the generator, and the 16VAC I am just using the 12VDC output of the generator too, as that is somewhat like AC and more at 22V levels, so when this goes into the board its rectified also and then passed to a 15VDC regulator and a 5VDC regulator, which is used to power the EGS002 driver board. So that side of thing works fine.If there is something else in that description of note, I have not clicked on to it however. Very poor translation.Yesterday I managed to get hold of an english speeking engineer from EGMicro who makes the Driver Boards used in this inverter. While he wasnt familiar with this model specifically as its made by another company, we discussed various parts of it and I am a bit happier with the whole thing now.So there is a feedback shunt, which is marked as 0.1ohm in the schematic example in the EGS002 datasheet, which is used to determine if the voltage goes over 0.5V over this resistor, so it can stop the output to save the FET's. It however is a little on a slow side, and in my case the Surge I enduced from the angle grinder would have happened too fast.In my case, these shunts I believe are 0.02ohm each, and in my model there area 2 of them. So 0.5V/0.02ohm=25A and I have 2, so 50A. So in theory if the current passing gets to be 50A then the inverter will trip and save itself. But for surge it happens too fast, as the IFB pin sample time I believe is 600mS.Anyway, I got talking with the engineer, and brought up these NTC's, and showed him another schematic I had found which uses these same driver boards, and features an NTC on the 220VAC output, and is used for exactly this - Surge protection.You can see it near the top centre of this imageThe engineer agreed, and said the NTC could solve the problem.If I for example aimed for a 10ohm NTC, then at 25 degrees C, the NTC resistance will be 10ohm. As the Surge hits on startup, it will be like a 10ohm resistor, and block current over 220/10=22A approximately. As the current flows, the NTC resistance will drop down to almost nothing due to the NTC warming up, and then full current will then pass unhindered. The question is though how big should the NTC be. 10ohm, 10A steady current capable?There is then the side of it which is the recovery time, how long it takes for the NTC to cool again to come back to 66% of the initial resistance or something, which in some of the larger NTC's could be over 100 seconds. SO I assume if I was to surge with an angle grinder, it saves that, then turn it off, and start the angle grinder again, would it save the next one... I dont know.The FET's I have in it currently are rated 650V, 47A @ 25C, so I would hope that preventing surge over 22A would be enough to save the FET's. Some items like a fridge compressor etc might not like this 'soft start' approach, but for most things it should be OK, right?Not looking for a rocket science solution here, but would something like this work for basic protection of the FET's?After the Surge is taken care of, then the shunts with the IFB protection can work as normal.Would love to know what people think.10ohm 10A NTC's from Aliexpress are about $1 each. 10ohm 15A NTC's are about $7 each.Thanks

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: January 30, 2019, 09:25:51 pm
content: Quote from: schmitt trigger on January 30, 2019, 04:03:56 pmI landed up on a French Language page trying to make sense of the 'technical specification'. Typically, when it comes to tech specs, the language doesn't matter so much. However, after second visit, I managed to stumble upon the "Original English" description page, aka the Chinglish Description page as you've just quoted. Sheesh! I can't imagine what a nonsense a French translation of Chinglish would look like to a native Francophone!That seems to be describing an ancient digital switching sinewave synthesis technique based on a bunch of tapped transformers which that inverter module is most definitely not. The eight powerfets on the heatsink suggests the use of a pair of class D amplifiers in bridged output mode with sample filter inductors designed to filter the 5 or 8KHz sample rate typically used in these 50/60Hz inverters.I'm surprised if the absence of any form of overload protection is actually true. The Chinglish description could be hiding any number of 'standard features' by simple omission. However, the description seems to be one made up by the manufacturer and appears to be total and utter bollix. Personally 69 dollars is at least 60 dollars too much to take a punt on it being any use. It might turn out to be perfectly fine but that's not something that can be discerned from its current description.JBG

author: WanaGo
author_rank: Regular Contributor
timestamp: January 30, 2019, 09:37:34 pm
content: Ignore the chinglish description, the circuit is much the same as that above, and what is posted in the reference schematic in the EGS002 datasheet which I have linked in previous posts.The main difference is the one I have has an extra Toroid on the output which is used to help with EMI, so I am told by the engineer.For 1000W and 2000W models, there are 4 FET's. For 3000W there are 8 FET's, to simply move more power.On these models there is no actual protection circuitry other than the IFB pin which I have already mentioned, which is somewhat slow so would be for general current overload, and then there is temperature protection from a thermistor which is bonded into the heatsink, and then voltage feedback which is adjustable to modify the nominal output voltage too.Some other inverter designs I have seen which are more for Battery inversion to 220VAC, but still using the EGS002 drivers, do have over current, over/under voltage etc protection, however I have not yet found any published schematic on these circuits.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 30, 2019, 09:54:24 pm
content: Here is a vid I found on Youtube, sadly it's in Portuguese, but Youtube auto translate to English subtitles gives somewhat useful information I guess.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 30, 2019, 09:58:08 pm
content: Here is another one in Russian, but auto translate to English is also somewhat helpful

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: January 30, 2019, 11:50:35 pm
content: Quote from: WanaGo on January 30, 2019, 09:37:34 pmI think you may be overthinking the overload protection aspect here. You have to remember that the 380v is not coming off a 100A battery supply but from the more limited capability of a 3 or 4 KVA genset. An overload is more likely to stall the engine before burning anything out. The slower speed of the built in overcurrent protection is there to deal with the edge case of sustained overload that's not quite sufficient to stall the engine or trip the genset's own breaker. These inverter modules are surprisingly robust.The more sophisticated inverter/engine management unit in that little Parkside PGI 1200-B2 is rated for a continuous 1KW output (or with my particular example, 980W - not a trimpot in sight so I'm waiting for Lidl to get some more back in stock so I can test and swap inverter modules if the next is set to a more reasonable 1020 to 1050W overload set point and return the donor machine for a refund). It has an overload capability of up to 1200W for 30 seconds duration (not the 5 seconds claimed in the user guide). If it's overloaded above the 1200W mark, it shuts down the inverter immediately as you'd expect. TBH, I was quite surprised at this half minute endurance against modest overload surges, especially after reading the 5 seconds overload spec given in the owner's manual.JBG

author: WanaGo
author_rank: Regular Contributor
timestamp: January 31, 2019, 12:13:06 am
content: As mentioned already though, I can run drills and angle grinders directly off the raw AC from the generator without issue, the engine hardly blinks an eye.Yet when I ran the angle grinder off the inverter, it blew the FET's up.So not quite sure what you are saying here, as the generator side of things seems to cope fine, and the inverter doesnt, so its the inverter I can trying to protect with the NTC idea, to try and stop the FET's blowing from surge loading from things like an angle grinder.Yes the generator isn't a large battery, but at the same time it seems to handle the output required to start the angle grinder...Thoughts on this...

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: January 31, 2019, 03:45:02 pm
content: Quote from: WanaGo on January 31, 2019, 12:13:06 amThe only thought I have on this is that either the switching FETs are too underrated for the task or else there's a design flaw subjecting them to high voltage transients. If you're still waiting on the 3000W version to turn up, you might have better luck with that seeing as how they've doubled up the FETs in that design.JBG

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 31, 2019, 06:56:13 pm
content: WanaGo;I know for a fact, as stated earlier, that series wound motors as found on these types of tools, draw very significant inrush currents.Do you have access to a current clamp meter? Otherwise, we are only speculating at the current surge levels.

author: WanaGo
author_rank: Regular Contributor
timestamp: January 31, 2019, 07:56:26 pm
content: Yep I have a current clamp meter. Just not sure its fast enough to capture surge, but ill give it a try.

author: Circlotron
author_rank: Super Contributor
timestamp: January 31, 2019, 08:37:43 pm
content: Measure what it pulls with locked rotor and 24VAC applied. Then multiply by 10. Actually it might pull way more because presumably the magnetic would be saturated?

author: WanaGo
author_rank: Regular Contributor
timestamp: January 31, 2019, 10:03:51 pm
content: Measured 10 times or so, the highest I saw the meter read was 7.5A on startup.It however is a UNI-T UT210E, so the update rate is not very fast, and there doesn't appear to be a MAX type feature. So I don't think this is really indicating the true current surge.

author: james_s
author_rank: Super Contributor
timestamp: February 01, 2019, 01:41:15 am
content: It takes only a very, very brief excursion outside of the SOA for a mosfet to fail.

author: WanaGo
author_rank: Regular Contributor
timestamp: February 01, 2019, 02:17:55 am
content: Yeah. So do you think the NTC idea will be OK?Speaking to the engineer of the company that makes the driver boards for these things, again, he suggested 2x NTC 10D-20 in parallel should do the trick.10ohm 10A steady, 20mm diameter, in parallel making it 5ohm 20A capable I guess.Should restrict to about 220V/5R=44A, which the FET's I think can handle, as they are rated to 47A continuous @ 25C.Thoughts?

author: WanaGo
author_rank: Regular Contributor
timestamp: February 01, 2019, 07:29:10 am
content: https://www.ametherm.com/inrush-current/inverter-inrush-current-protection