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Forum Index : Electronics : Building a new Inverter.
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Madness Guru  Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Sorry I missed the part about grid tie charge only, The information is spread over so many forums and threads it is a lot to get through. With our weather here in coastal SE Qld we can get weeks of heavy cloud and little solar charge. Just had 6 days of it and the batteries where down to 40%, maybe your weather patterns on Flinders Island gives you shorter periods with out good sun. But here a backup power source is need unless I had maybe 20 or 30 KW of panels. Can you tell me where these Meanwell PSU's can be bought at those prices? I have been thinking that perhaps a home brew Toriod tranny with a rectifier and PWM regulation might be a good high power (8KW) charger to connect to my generator. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Not sure about Australia, but over here in NZ, grid-tied inverters must be type-approved, so you can't connect you own home-bake one to the grid anyway, only expensive commercial ones with approval stickers. The fear from the power company is in case your inverter arrangement sends some kind of nasty down the line to the network and causes damage to something in their network infrastructure - a perfectly valid concern I suppose. Australia and New Zealand seem to share many regs, so there is probably something similar over there, if not MORE intense, as I seem to remember reading in Silicon Chip magazine how Australians aren't even allowed to wire up your own three-pin plugs without an electrician signing off on it just about - that was a few years ago, so things may have - hopefully - changed by now. Smoke makes things work. When the smoke gets out, it stops! |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Grogster, in Aust we have AS4777 for grid tie. The grid tie I was referring to is a home grid... not an real power grid. Ie hook a grid tie unit to your inverter output, then when the sun shines, it helps run your loads, if loads are too small it will run backwards through the inverter to the battery bank, acting as a charger. On BSI ( bass strait islands) Hydro Tasmania has allowed us to override as4777, and go 4hz plus or minus because of their inability to hold 50 hz ( normally +-.5hz) with diesel and wind. Inverter still has to be as4777 BUT with software alteration.... no home brews allowed. So it has to have been a CEC approved unit in the first place, and you must be able to get the software altered for the wider bandwidth..... fat chance in most cases.... but now you can have it specified BEFORE it gets installed by the installer. I bought my last meanwell style power supplies here http://www.ebay.com.au/itm/AU-Stock-DC-12V-Universal-Regulated-Switching-Power-Supply-for-LED-Strip-CCTV-/251536308755?v ar&hash=item0&_uhb=1 They have gone up as our dollar has gone down apparently... still excellent value as a controlled charger. If you use a torroid ( don't) you will need very big chokes to control the current. For battery charging you need loose coupled windings, with lots and lots of leakage... everything a torroid is not. If you do use one, you need to control the current somehow... chokes and big ones at that. Otherwise it will blow every fuse in the place when the battery is flat, and not charge when the battery is nearing full... ie it is too stiff for the range... torroids do not range very well, they tend not to sag under load, so go from over power at low SOC and no power nearing full state of charge. I suppose if you wound for the right voltage, and used a choke for the low SOC, it would run out of steam at full SOC, and maybe not require a controller of any kind... interesting idea. PWM of the output is the only other good way to utilise a torroid I guess, and would be worthwhile trying. I use a little 120amp 60v one for my solar charging, so it is quite doable. .....oztules Village idiot...or... just another hack out of his depth |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Hi Oztules, I like the idea of the PWM, then current and voltage can be controlled allowing any AC generator to become a bulk battery charger. Add a timer to shut it down a set amount of time after the voltage set point is reached and let it go. That coupled with you Inverter for the output and you have always got as much power as you need. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
All very true as long as you have a inverter with transformer as all H bridges work both ways. The later transformer-less inverters wont work in reverse. Albeit the average inverter has no voltage charge control in reverse through the inverter, meaning they will boil the batteries without voltage limiting externally added. Sometimes it just works |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
The transformerless are going to removed from the market 9/10/2016 too. " The CEC will not list non-isolated (transformerless) stand-alone inverters, as these do not comply with the installation requirements of AS 4509.1 (refer to Clause 9.3.3)." AS 4509.1 There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
CEC certification is only to get Govt monies. I agree with their non listing transformerless units, I think they are junk from the start, and I would not co-sponsor them with Govt money. Edit I re-read that.... what is a transformerless inverter. Do they mean boost circuit inverter, or a hF transformer... the HF units are isolated anyway and have a HF transfromer( but I don't like them at all), and I have not seen any boost converter circuit units... but that would be possible.... They probably differ to me as to why not. Downwind, that observation is almost correct.... except it did not stand up to practical observation.. In the real world, GTI using AS4777 will self regulate as a normal function????.... not by design, by happy coincidence. I used a battery voltage disconnect at 59v and reconnect at 55v... thinking as you do/did. In practice, it just runs up to about 59-60v, and then raises the AC line voltage as the current drops off near full SOC, and shuts down because of over AC voltage instead...waits 3 mins and does it again etc etc So I don't bother with my circuit anymore, it looks after itself in winter, in summer I may use the voltage switch as the days are longer, but a cycling FLA loves this nonsense better than under charging by a mile..... no good for standby obviously, or other battery technologies. ..............oztules Village idiot...or... just another hack out of his depth |
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Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429 |
Downwind, I can confirm that the OzInverter back charges very nicely from GTI's that are connected to the OzInverter's 230vac Mini Grid. One of my main reasons for doing the OzInverter was its ability to accept GTI's charge the batteries, and when they start to fill and are full the AC voltage rises and at 243v the GTI drops out. I use second hand, and new old stock SMA SB2500 and SB3000. I also have the Control codes I can re-set those AC drop out voltages sequentially. I also have 5kW PV that has DC controllers, Tristar MPPT and the Midnite Classic 200. The Classic charging regime is excellent and I have a fail safe switch on each GTI that operates when the classic goes to float. I finish the 1300ah AGM batteries with the 5kW of PV on the DC Controllers. But so far the GTI drops out just right. Another thing, good DC controllers are dam expensive, but SMA Sunny Boys GTI's below 3000 are as cheap as chips. 3 brand New SB2500, (old stock) cost me about $450 here in Europe. Another thing about the OzInverter is its toroid windings, as we are in control of them we can keep the Toroid transformer tight. I never see my DC go above 59.5v on a bulk charge from the GTI. So my hat is duly doffed to 'oztules' for that. Oh just one more, I find the SB's GTI's rather good at squeezing every last drop of the PV, so on even dull days, ambient light I am still getting 10%, those 10%'s add up. Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Thanks Clockman, some good observations about how the hand wound toroid behaves. I have tried the AC coupled approach several times with off the shelf gear and could never get the operating windows of the GT inverter and batteries to match. It took me several years to realise that we dont need a bank of high tech networked DC controllers. I went down the same path as Oztules, with the clients who would listen, expanding their systems with panels with 6 inch cells, wired in pairs and simple charge controls. One fancy controller works its magic with the batteries at the top end, the rest (simple ones) just bulk charge and cut out a fraction earlier in a staggered sequence. the only thing I have added to that combination in the last few years it a big contactor that protects the batteries from extreme over and under voltage. I'm confused, no wait... maybe I'm not... |
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| Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429 |
Hi yahoo2, I just love the simplicity of the OzInverter. I feel sure folk could build from it, with auto load shedding, charging regime etc etc using Arduino, nano etc. After dealing with that well known Company and its product that would not do what I wanted, unless I spent a small fortune on its ancillary must have to get it work right products, The OzInverter is indeed a breath of fresh air. Personally speaking, Ac Coupling and using those cheap GTI's (thanks to the mass market PV on domestic house roofs Guys), Is a very cost effective way of collection and control, especially that 10% from PV on gloomy days. Here is a link to our Web site, its not much but its a start. http://www.echorenovate.com/the-ozinverter.php Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Just been looking at ordering a core from this supplier http://www.alibaba.com/product-detail/Grain-Oriented-Silicon-Steel-toroidal-core_60477443336.html?spm=a2700.7743248.51.1 .Hm61oV Is there a particular thickness and type of the core material that is best suited to this application. Options are A2: (1) Grain oriented Silicon steel: Grain oriented Silicon steel: 0.05mm / 0.08mm / 0.10mm / 0.18mm / 0.23mm / 0.27mm / 0.30mm / 0.50mm; Grain non-oriented Silicon steel: 0.35mm / 0.50mm Super Core (grain non-oriented silicon steel): 0.10mm (2) Amorphous: 2605SA1(28μm) for distribution gap cores; 1K101(28μm) for C-Cores. (3) Nano-crystalline: 1K107B(23μm) I know Oztules and others have stacked 2 cores together but if I can get the core made in one piece is that better. What I am planning to get is a core 230 mm OD 100 mm ID 140 mm wide, it looks like the supplier can go up to 800 MM wide so is 140 wide the way to go? Thanks Gary There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429 |
Hi Gary, This firm.... http://www.airlinktransformers.com/toroidal_cores/technical-notes/ Is our European supplier, they wind there own and have a fair stock of bare cores. The cores I use are 0.3mm thick wound strip Silicone Iron alloy. Have a look at there specs for guidance. As far as I am aware there is nothing between the laminations of the core. See the note on varnish in the laminations and degrading. For the 6kW OzInverter 200mm OD, 100mm centre hole 120mm high, is about 26kg for the bare cores. That size you have mentioned is my latest BigOzInverter size and that core is 39kgs. At that weight winding becomes problematic as the normal procedure bench, (as in the book) is not going to work. The 39kg toroid is difficult to pick up and rotate about a 6th. Also at that heavy weight the coating on the coated copper wire is easily scratched/removed/abrasion as we don't have as many turns on each winding. For mine I have done a 3mm thick rubber matt that only supports 3/4 of the toroid, so I can get my full hands in to lift cleanly and turn with safety and put down cleanly. Trust this helps. Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Thanks Clockman, I have sent the details to the Chinese supplier, I fear delivery cost from Europe to Australia would be rather high. I will post the quote when I get it. I have gone with your recommendation on size. Gary There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
After lots of searching and nothing I finally hit the jackpot. Picked up 6 3 KW Aero Sharps today, if anyone is interested there is another 30 where these come from. 
There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Congrats, 3kw is perfect. I watched a pallet of 12 sell for no money at an auction a few years ago, kicking myself now. I'm confused, no wait... maybe I'm not... |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
I wish I could find that kind of thing over here....  Smoke makes things work. When the smoke gets out, it stops! |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
There is 30 sitting in Brisbane they might freight them they weigh about 45 KG each. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Lovely thought, but I expect probably not - the weight of them would make the shipping pretty expensive I would think, however I would still be interested in that idea. Could you please either post the contact details for them, or flick me a PM with that info if you don't want to post that publicly. Out of interest, what do you think they weigh? EDIT: You edited and put up weight - thanks!  Smoke makes things work. When the smoke gets out, it stops! |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Just sent you a PM Grogster with contact details, I won't post it online but if anyone wants it just PM me. They are heavy things, even the heat sink is over 1 KG. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Grogster If you can get hold of one and get someone to pull the transformer, the weight may become more likely to be normal mail weight.... like 16kg or so.... maybe Mad can weigh his transformer if he has not yet started rewiring it. Much cheaper than sending the 45kg complete..... although the box is very very nice too....maybe even get the folks selling them to strip and send for a few extra dollars. Won't hurt to ask anyway. ...oztules Village idiot...or... just another hack out of his depth |
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