[No]Should I design an inverter? - Page 1
Forum section: electronics / general

author: blueskull
author_rank: Unknown
timestamp: June 25, 2016, 01:56:04 am
content: I've been suffering from power outages for a while thanks to the power company does nothing on maintaining their wires.I bought a Black and Decker 500W inverter just in case. Well, I had a chance to use it, as we had another power outage yesterday evening. To my surprise, it can not even power 2 22'' monitors, let along the computer.I searched on Amazon for some good deals, and this time I was focusing on higher quality pure sine wave ones. Unfortunately, none of the low power ones look well built -- I do not want to waste money on a well build 2kW+ system, I just want to get a high quality 500~600W one.Also, most cheap inverters use input ground as HV bus ground, that poses some safety hazard. I want one with its neutral wire connected to ground, or the HV subsystem completely isolated.So, should I spend some time on building a super high efficiency 600W inverter? I do have the technology to build a 96%+ efficiency one, but that will cost me some time, at least a week, 2 hours per day. Do you think it's worth it?New design thread startedhttps://www.eevblog.com/forum/projects/weekend-project-pure-sine-wave-inverter/.

author: Rerouter
author_rank: Super Contributor
timestamp: June 25, 2016, 02:08:31 am
content: How about something like this?http://www.ti.com/lit/an/slaa602/slaa602.pdfOnly painful part in my head would be the magnetics, as those tend to be expensive for those power levels,

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 25, 2016, 02:11:32 am
content: Check to make sure the inverter you have is not a fake? A real 500W inverter should have no problem running most home electronics.

author: MK14
author_rank: Super Contributor
timestamp: June 25, 2016, 02:15:05 am
content: Quote from: blueskull on June 25, 2016, 01:56:04 amObviously you used it in "500 Watt" mode ?NOT in "100 Watt" mode, via the car lighter input thingy and/or socket ?tl;drIt is limited to 100W, depending on how you connect it up (apparently).

author: rx8pilot
author_rank: Super Contributor
timestamp: June 25, 2016, 02:37:55 am
content: I will only consider sine wave inverters for continuous use. Modified sine is a mess.Sent from my horrible mobile....

author: MK14
author_rank: Super Contributor
timestamp: June 25, 2016, 02:43:59 am
content: Quote from: blueskull on June 25, 2016, 02:28:37 amOk, sorry if you thought I was being rude.You might be very surprised, if you knew some of the silly mistakes, apparently well educated electronics engineers and similar can make.

author: mtdoc
author_rank: Super Contributor
timestamp: June 25, 2016, 02:50:59 am
content: Forget about crap Home Depot B&D inverters and the like. A quality 600W PSW invertercan be bought for less than $200.Should you design and build one? It depends on how much your time is worth or whether doing it is a worthwhile project in itself.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 25, 2016, 03:55:36 am
content: If you only want to run electronics, just have it output 170V or so DC.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 25, 2016, 04:47:36 am
content: There's a big push for HVDC power distribution in the data center for efficiency reasons. Apart from reduced losses at the source, it also reduces losses at the load. That's especially true for loads with PFC.Now if you're planning on making it capable of driving motors, do it right by making it a full fledged VFD. Doing a V/Hz soft start really helps start motor loads, just beware there may be patent issues if you're planning on selling it. Scaling down the voltage/frequency reduces the power usage of motor loads and can easily extend battery runtime by a significant amount.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 25, 2016, 05:12:30 am
content: I think the patent (if it exists) specifically focuses on standalone single phase inverters that use the V/Hz ramp up to ease starting of motor loads. Vector (a brand of cheap but decent inverters) once implemented it but no longer do, while Samlex (one of the premium brands of inverters) has been offering it for a long time. I have a 400W Vector that I reverse engineered and the soft start feature is just a ramp up to 120v/60Hz in about half a second. A simple RC circuit is what controls the ramp up and costs very little to implement. In a higher end inverter with digital control, the ramp up is merely a few lines of code that costs virtually nothing to implement.

author: Seekonk
author_rank: Super Contributor
timestamp: June 25, 2016, 12:55:00 pm
content: Check out the 8010 boards on ebay for about $7. A complete sine wave driver board, just add FETS for H bridge or transformer. Just about plug and play. Seehttp://www.fieldlines.com/index.php/topic,148953.0.htmlfor an example of use. There are several threads there related to this.

author: station240
author_rank: Unknown
timestamp: June 25, 2016, 05:37:35 pm
content: If you can build a 500W 96%+ efficiency inverter then go for it.Vampire current draw, and efficiency do seem to be common problems with store bought ones.Hence you either reduce the life of the battery (risk of overdischarge), or just get less runtime.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 25, 2016, 05:48:18 pm
content: A good part of the idle current is due to the output filter. (Same effect happens in some audio amplifiers, often to an even greater extent.) That can be reduced with a lower loss inductor (will increase cost and size), but why when the simple way out is to just output DC if you're running electronics? For motors, it can make more sense to run them off PoL inverters (VFDs) that can vary the frequency a much wider range than a general purpose inverter can.

author: ez24
author_rank: Super Contributor
timestamp: June 25, 2016, 06:58:13 pm
content: Does China have Home Depots? (your flag says China) Would love to see some pics of one. I wonder if they look like our Ikea.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 25, 2016, 06:58:44 pm
content: Try changing the polarity of the input? A few PSUs need the DC polarity one way for them to start.Transformer isolation doesn't work very well at the extreme duty cycles often found in inverter applications.

author: diyaudio
author_rank: Frequent Contributor
timestamp: June 25, 2016, 08:26:02 pm
content: Quote from: blueskull on June 25, 2016, 01:56:04 am600W, x1 EPCOS etd54 + simple SG3525A + fets, pcb.however R&D time is the most expensive aspect especially winding those dam transformers manually and getting the control loop control stable. at that power level, its worth trying for.

author: bitslice
author_rank: Frequent Contributor
timestamp: June 26, 2016, 01:16:16 am
content: Quote from: blueskull on June 25, 2016, 08:09:09 pmWhich isn't super helpful when other people are trying to evaluate your options...btw, derate any inverter by 5 to get the actual output. Yo marketing.

author: rx8pilot
author_rank: Super Contributor
timestamp: June 26, 2016, 01:58:17 am
content: It could have been the inrush current from startup that shut it down - not the average current.

author: mtdoc
author_rank: Super Contributor
timestamp: June 26, 2016, 02:30:09 am
content: Quote from: bitslice on June 26, 2016, 01:16:16 amIt depends on the brand. My Outback inverter meets it specs without breaking a sweat.Like most things. You get what you pay for.Any good inverter will have a brief max power output far above it's rated output to account for motor or compressor startups, etc.

author: Seekonk
author_rank: Super Contributor
timestamp: June 26, 2016, 11:32:08 am
content: How can you not like this solution?http://www.ebay.com/itm/Pure-Sine-Wave-Inverter-Driver-board-EGS002-EG8010-IR2110-Driver-Module-/171460635650?hash=item27ebd9ac02:g:iuIAAOSwfcVUKkIe

author: TerraHertz
author_rank: Super Contributor
timestamp: June 26, 2016, 12:33:27 pm
content: Quote from: Seekonk on June 26, 2016, 11:32:08 amhttp://www.lz2gl.com/data/power-inverter-3kw/eg8010_datasheet_en.pdfThe module manual:http://www.egmicro.com/download/EGS002_manual_en.pdfWTF? Why is the Neutral line being driven, and without filtering? [reads datasheet...] Oh, I see. Urrgh. That's completely unacceptable.This thread is interesting. But if someone (or several cooperatively) were going to do an open-source mains inverter design, rather then just jumping into schematics a better initial stage would be a thread discussing design objectives.Because there's a lot of potential to do something really useful, considering the various reasons why there doesn't seem to be an open source 'power independence' inverter system already.For example, the design could ignore:- patent restrictions.- government policy prohibiting true grid-tied/grid-free/no-dropout transitioning systems, able to do 'quiet grid load profiling'. ie injecting power into the local side of a grid-tied system, to reduce consumption from the grid, while looking like a standard power-consuming household. For when you have some local power source, but don't want to announce it to anyone, and it's illegal in your area to actually disconnect completely from the grid. Or you do still need grid power sometimes.- government prohibitions of building-cluster or small community private distributed power sharing systems.Also including:- Ability to disconnect (main contactor) from the grid and reconnect, without transients and dropouts. Means your local inverter has to be able to accurately sync up to and waveform-match the grid before reconnecting, and smoothly shoulder all your local load before disconnecting.- Basic inverter module (of say 1KW) able to be paralleled up for higher power and redundancy.- Ability to run one, two or three banks of inverters, phase locked correctly to provider single or three phase power for machine tools. (or 2 phases if needed for some reason.)- Flexible power origin and storage management subsystems. Solar panels, battery banks, local DC LV household bus, etc.

author: TerraHertz
author_rank: Super Contributor
timestamp: June 27, 2016, 12:33:49 am
content: Quote from: blueskull on June 26, 2016, 06:45:36 pmBecause in their reference design, the Neutral line has an unfiltered non-sinusoidal HV signal on it. This means it can't be used with standard home wiring since a) not safe, and b) lots of EMI radiation. Oh, and no DC isolation between AC mains and battery system.QuoteSorry, I am aware you just need a quick fix. I should have made it clearer I wasn't criticizing your efforts. Just commenting that it could be useful if this forum also did a wider scope inverter design process, with an initial 'decide on objectives' stage.QuoteYou're right, I am. Though substitute 'corporate & financial-elites fascism' for 'government'. Government operating under the thumb of the financial powers is just one face of that evil. Not unique to any country.Being critical of such things is not an unusual position these days, and for good reason.I do understand your position on this, and on the other matter. Yours is also a widely held view. A little cowardly, and in general people ignoring wrongs and saying nothing enables the excesses of the power-hungry bastards, but it's your choice. (One you may ultimately regret, I think.)"And how we burned in the camps later, thinking: What would things have been like if every Security operative, when he went out at night to make an arrest, had been uncertain whether he would return alive and had to say good-bye to his family? Or if, during periods of mass arrests, as for example in Leningrad, when they arrested a quarter of the entire city, people had not simply sat there in their lairs, paling with terror at every bang of the downstairs door and at every step on the staircase, but had understood they had nothing left to lose and had boldly set up in the downstairs hall an ambush of half a dozen people with axes, hammers, pokers, or whatever else was at hand?... The Organs would very quickly have suffered a shortage of officers and transport and, notwithstanding all of Stalin's thirst, the cursed machine would have ground to a halt! If...if...We didn't love freedom enough. And even more - we had no awareness of the real situation... We purely and simply deserved everything that happened afterward."-- Alexander Solzhenitsyn {1918-2008), The Gulag ArchipelagoBy the way, not long after this article appeared:20160502http://www.womenofchina.cn/womenofchina/html1/news/china/1604/2230-1.htmPresident Xi Jinping Asks Officials to Respect Intellectuals' Creativity, Criticismthat person I spoke to you about began posting again, and is OK. Ostensibly no connection between these events, but then if there was, it wouldn't be admitted.QuoteSure, quite useful, especially given the crappy quality of cheaply available inverters. I have something much the same, for car camping. Couple of solar panels, a commercial panel-battery management unit, large 12V lead acid battery, and a small inverter. For remote car-camping, it's not a good idea to draw from the main car battery.I can also use it at home during power outages, but since the cable Internet also goes down then, it doesn't help much.One reason I keep an old fashioned wired phone land line. No net via it though.But for home power, it annoys me that the standard grid-tied no-battery solar panel installation inverters seem to all be designed to deliberately be impossible to adapt to stand-alone battery storage operation. And systems that are designed to run in isolation with batteries, don't seem to have provision for agile grid connect/disconnect.Seems like the official reasoning is "we will subsidize grid load reduction via solar, but certainly won't allow anything that might provide suburban households with an option to disconnect from the grid, either intermittently or permanently."Btw, with your system don't forget that the car battery is grounded to the chassis. If your 120V AC output is not isolated, and somehow gets connected to other household wiring, you might end up with a dangerous voltage between your car body and ground.

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2016, 01:02:40 am
content: Quote from: blueskull on June 26, 2016, 06:45:36 pmWhy not just get a small generator set? An alternator in a car doesn't work very well at idle speeds.A long time ago I equiped a car with a reasonable amount of computer equipment and used a 2kW pure sine wave inverter to turn 12V into 230V. Maybe the actual load was around 500W but even that made the new alternator smell (I had the car equiped with the most powerful alternator which fitted on that car). Still when running idle for longer periods the alternator just couldn't keep up and the voltage dropped below the inverter's threshold. Luckely I also included a UPS in the setup which then took over (there was more cleverness in this system BTW).

author: Red Squirrel
author_rank: Super Contributor
timestamp: June 27, 2016, 02:15:13 am
content: It seems the market is flooded with cheap square wave inverters, would be nice to see more availability of pure sine high capacity inverters.What would be neat is rackmount inverters where you can add modules to add more capacity. Then it would feed say, a 100a transfer switch that goes to the main electrical panel. You could then have solar system or other power source power the inverters, but if that system fails you can transfer to regular commercial AC.

author: mtdoc
author_rank: Super Contributor
timestamp: June 27, 2016, 02:19:38 am
content: Quote from: TerraHertz on June 27, 2016, 12:33:49 amNot true at all. Outback Power, Schneider Electric, Magnum, SMA, and others all sell such inverters.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 27, 2016, 04:31:46 am
content: Quote from: blueskull on June 27, 2016, 01:41:12 amSince you're only running electronics, DC most likely is all you need. Assemble the DC/DC part of your design first and if it works, call it done!

author: TerraHertz
author_rank: Super Contributor
timestamp: June 27, 2016, 06:52:07 am
content: Quote from: mtdoc on June 27, 2016, 02:19:38 amOthers might find useful the result of an hour I've spent hunting up those companies and distributors and reading their advertising.---------http://www.outbackpower.com/17825 59th Ave. NE, Suite B, Arlington, WA 98223 USAOutBack Australia: Suite 2 32-34 Peter Brock Drive, Eastern Creek NSW 2766Phone: +61 (2) 8599 6960They call it grid-tied partial state of charge (PSoC)http://www.schneider-electric.com.auUrrgh. over-complex website, doesn't work even with firefox. Can't get to details of inverter systems.http://www.magnum-dimensions.com/http://www.magnum-dimensions.com/renewable-energy-products/NE USA only. Not much for international market. Can't find any grid-tie partial...http://www.sma-australia.com.au/Headquarters: Niestetal, GermanyGlobal presence: sales and service subsidiaries in 20 countriesAustralian Authorised Distributors:RFI SOLAR Tel. 1300 000 734http://rfisolar.com.au/99 Station Rd, Seven Hills NSW 2147Sol Distribution Tel. 1300 660 483http://sol-distribution.com.au/Unit 14, 39 Herbert Street, St Leonards NSW 2065Solar Juice Tel. +612 9725 1111http://www.solarjuice.com.au/Unit 1, 10-12 Forsyth Close, Wetherill Park, 2164 NSWSolar + Solutions Tel. 1300 255 410http://solarsps.com.au/456 Lower Heidelberg Rd, Heidelberg VIC 3084More inverter manufacturers:ABBZeverSolar Evershine TLC8000 - 3 Phase, Dual MPPTKstar---------Just starting a file. As for the original question of flexible grid connection, it seems now there are some. Still not many; most are still either grid-tied or independent. And good luck trying to find any technical details on _any_ commercial inverter.I still say there's a need for an open-source project here.

author: mtdoc
author_rank: Super Contributor
timestamp: June 27, 2016, 05:02:26 pm
content: Quote from: TerraHertz on June 27, 2016, 06:52:07 amThe term normally used is "Grid Interactive" aka "Grid tie with battery backup"I'm most familiar with Outback products.Their Radian lineis their flagship grid interactive capable inverter/charger. I suspect it can be adapted to non-North American power specs but I haven't investigated.]Here is a listing of their all their North American market (60Hz) grid interactive unitsThe do have inverters for the international market - 50Hz etc.This page has someand I believe there are others available as well. I'd call Outback Australia.There is full documentation of specs and manuals for each inverter linked on that website. They also havean active user's forumThey make high quality inverters and have a reputation for excellent customer service - which I've had first hand experience with in the past. This may have changed in recent years - since they were acquired by the "alpha group".Quote from: TerraHertz on June 27, 2016, 06:52:07 amYeah - Schnieder bought Xantrex a few years ago and took over their inverter line. Their venerable XW line was a top grid interactive capable inverter for years. Now updated and called the "Context XW"You canfind details here.Click on one and under the details tab is documentation. I believe these can be programmed to international 50Hz output and voltages.QuoteYeah, my bad. I'd thought Magnum had a grid interactive model. They do make good off grid inverters.QuoteThe SMA Sunny Islandit their grid interactive model. It is high quality.QuoteI have no knowledge of any of those manufacturers.One I forgot to mention isVictron EnergyThey are a Dutch company that do not market in the US much but they make high quality inverters - some of which are grid interactive I believe.QuoteI agree - it would be great to have that as well.

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2016, 05:11:21 pm
content: Quote from: blueskull on June 27, 2016, 01:41:12 amModern small generators are very quiet.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 27, 2016, 10:06:05 pm
content: Quote from: nctnico on June 27, 2016, 05:11:21 pmIs there one that would be efficient at just 150W load? Granted, leaving a car idling won't be efficient either, but that only needs to be run part time with the help of a deep cycle battery. (Or use some other source, such as solar panels, to charge it.) 100Ah class deep cycle batteries can be found for under $100 and with the 50% derating, will run 150W of load for 4 hours.

author: mtdoc
author_rank: Super Contributor
timestamp: June 27, 2016, 10:20:24 pm
content: Quote from: NiHaoMike on June 27, 2016, 10:06:05 pmYou'd want an inverter generator which will allow power output to be independent of engine RPM. They do cost more.Honda EU generators are the standard. The smallest is 1000W. Google EU1000.Yamaha and other companies also make similar models.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 28, 2016, 01:00:58 am
content: I'd be surprised if it would be as efficient as an inverter running from a battery and running a generator part time to charge it. It's pretty difficult to make a very small engine efficient. Not to mention it would be yet another device to maintain.Also, where in the US does the grid regularly go down for more than 4 hours (or even one hour) at a time? If a single deep cycle battery can cover most of the outages, it might not be worth the cost to improve the efficiency of the second level backup solution.

author: TheSteve
author_rank: Unknown
timestamp: June 28, 2016, 10:01:39 pm
content: Honda EU1000i or EU2000i - both wonderful options. I ran my EU2000i on the weekend in Eco mode(powering 100 watt amateur radio transceiver) for 13 hours on 1.1 gallons of gas. The bonus with an EU2000i is you can run the fridge/freezer/microwave if needed during a longer outage.Not as much fun as building your own inverter of course.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 28, 2016, 10:52:57 pm
content: Quote from: blueskull on June 28, 2016, 09:54:24 pmThat's more or less what I found when I worked on a 2kW inverter. A large portion of the idle losses are in the output inductor. (Same goes for many audio amplifiers.) One trick to reducing that loss is to period skip near the extreme duty cycles, lowering the effective switching frequency. Or just output a trapezoidal wave at low output power so there would be no switching over much of the waveform.HVDC eliminates that loss. Not to mention significantly lowering cost and complexity at the expense of making it only work on electronic loads.If you just want an off the shelf solution, here are more reviews than you could ever imagine existed:https://www.youtube.com/user/knurlgnar24/videosKeep in mind that if you want fancy features like V/Hz control, expect to spend a lot. But for the uses you listed, that would be irrelevant.

author: rx8pilot
author_rank: Super Contributor
timestamp: June 29, 2016, 01:10:46 am
content: Quote from: TheSteve on June 28, 2016, 10:01:39 pmI had a few of those for my business and loved them. Really fantastic for gas options.

author: Pineapple Dan
author_rank: Contributor
timestamp: July 25, 2021, 06:45:27 pm
content: I did design my own inverter. Well technically just a H-bridge and connected to an old transformer. It is ridiculously simple and hack-ish but one can run some stuff off ithttps://vimeo.com/manage/videos/523141818Should be able to make the output more sine wave-like by software but haven't tried this yetI doubt it will do 500W but I intend to design an improved version, I want something that I can pack in with a solar charge controller & batteries and be remote controlled, reset automatically after overload and so on. My shop-bought 1KW inverter will just give up and start beeping once the battery goes down or if it gets overloaded. With a home-made one it will be easier to work around those problems