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Forum Index : Electronics : Time for a new Warpinverter build
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| rogerdw Guru  Joined: 22/10/2019 Location: AustraliaPosts: 885 |
Haha, yeah. I have a reasonable number but not sure if I'm going down the track of mosfets or IGBTs yet. I figure I'll wind some transformers first then experiment. Thanks for the detailed description for using a hoop to wind. I've gone over and over it in my head and am fairly keen to try that way. And I know I'll overdo the amount I wind on to make sure I have enough ... but it would be more painful to come up short.  Agreed, that was an issue I could see happening ... so using your method made sense to me. The only other alternative I could think of was to fold tape around in several places ... but that would be an absolute pain and hold up the winding process. I have given some thought to finding some stiffer tube and cut the thin slot around the circumference ... then have a spider armed arrangement with wheels that hold the spool in position (from the inside) ... then when you need to rotate it, you can continue holding the wire taut with one hand ... and spin the hoop with the free hand. Probably too hard to create so I likely wont do it ... but it's fun to consider alternatives. I also like the idea of marking out the layout before you start as well. I use CorelDraw a lot, so figured I'd mark it out on screen and print out and stick it to the top and bottom to act as a guide ... especially as the first layer will be spaced quite widely and not up against the previous turn. As I mentioned above ... I was also trying to work out if I could 3D print a very thin layer with faint grooves to guide the wire also ... but would be nervous about potential issues with the printing material long term. Cheers, Roger |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 885 |
Haha, yep. I need to maintain momentum. You've certainly gained some experience winding toroids and building inverters, it definitely sounds like you've fine tuned the process well. I'm only just beginning my journey, so hopefully with all the experience in the group here I'll be guided on the right track. Speaking of momentum ... looks like I might have to go for plan b. I received a quote for 1 x 300mm OD x 120mm ID x 100mm thick toroid core and it was for $614.35 including gst.  In my naivety I was hoping it would be about half that ... and while I could pay that amount I suppose ... it kinda defeats the purpose of what I'm trying to achieve. (The initial quote for 2 x 240mm OD x 120mm ID x 70mm thick cores was for $371.80 incl gst for the pair) So looks like I need to take the standard approach and stack two 3kW AeroSharp cores and go that route. Of course that leaves the assembly with a 100mm ID ... not ideal for having a 5mm spacer between sec and core ... and sec and prim ... so need to make some decisions again. I had put in an order for another 3kW AeroSharp so will just have to wait till one turns up. There's plenty I can do in the meantime though. Cheers, Roger |
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InPhase Senior Member  Joined: 15/12/2020 Location: United StatesPosts: 178 |
That could be a huge problem. The hole will be on the outside of the toroid! Edited 2021-02-08 23:40 by InPhase |
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Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 671 |
Funny lot these yanks who post here. One is an attention seeking nobody who knows nothing but insists to pretend he does by adding his crappy posts. The other does not seem to know the difference between OD and ID. |
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| InPhase Senior Member Joined: 15/12/2020 Location: United StatesPosts: 178 |
You're right, I read it backwards. I thought he said 300 mm ID, 120 mm OD. I was just having some fun. Why are you such a twat about it? |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I am a bit dyslexic myself, and often do the backwards thing. Cheers, Tony. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
There's one in every crowd in phase Rogerdw if you haven't bought your mosfets yet There is a place "Aztec maybe" to buy them cheap 100 Hy4008 for around 100 bucks I have had good luck from this one store on AliExpress no fakery They sell many different types of mosfets and are likely to have what you need I have ordered many times from this store and had no problems If you need the store name and info I can look it up It is very convenient to have mosfets on hand And at 100 for a hundred bucks they are affordable to have lots on hand It's nice not to have to wait on mosfets Although many thought it silly I use the same physical size mosfets in all inverters I build So if a family member or friend has a break down I have parts on hand Out of around 20 no break downs yet but I have use mainly the china boards and it's only been a few years The things I told you about winding Transformers are facts by experience Alot of the tranny advice was told to me some I found out myself I have wound many trannys and told you what I have found to be fact I was hoping it would make it a little easier on you to get started because it can seem overly complicated You can do all the math and figuring in the world But it comes down to something very simple wind a few more turns and test it That's how to have it the best it can be I would recommend not to forget about the insulation in between all wires that have a very large difference in voltage Many will tell you it doesn't matter Transformer manufacturers use it and use more of it in higher-quality Transformers And trust me when I say men greater than I have gotten a turn or two off so test to on every layer I and many others will the cheering for your success in the background be warned i am good parrot but Dumber than a box of rocks |
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Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 437 |
rogerdw, These folk in Wales, UK, have been supplying my needs for many years. https://www.wiltan.co.uk/ Watch the start Video, shows a guy winding a good size toroid, old school. And yes, they ship anywhere in the World. They have always been helpful when i contact them, and the prices very good, last ones i had were M4 0.3mm 220mm OD x 100mm ID x 120mm thick at 130GBP each. And they now have lots more info on their toroid products, soft porn for 'Warpspeed'. https://www.wiltan.co.uk/toroidal-cores and ... Wilton Wound toroid cores. pdf.pdf I trust this helps. Edited 2021-02-09 19:29 by Clockmanfr 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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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
The Wiltan prices seem roughly comparable to our AEM cores here in oZ. AEM are the only company in the entire south east Asia Pacific region making these cores, its a pretty specialised business. The biggest problem is the cost of shipping, these things are enormously heavy. Cheers, Tony. |
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| Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 437 |
Delivery charge from the UK into Europe, ie, me in France, was 150GBP for a small pallet weighing 75kgs. Yes, if you can get it locally its better. 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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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 885 |
As mentioned above, I've decided to use a couple 3kW AeroSharp stacked cores for the largest transformer. That is definitely definite especially now that I've had a quote from Wiltans.Their cores are very reasonably priced ... but as expected, the freight is the killer. 260x120x120 - M4 bare GBP114 each exw = AUD $203.83 280x120x120 - M4 bare GBP137.10 each exw = AUD $245.13 260x120x160 - M4 bare GBP151.98 each exw = AUD $271.73 280x120x160 - M4 bare GBP182.79 each exw = AUD $326.82 GBP = United Kingdom Pound ... for some reason the forum will not accept the pound symbol!!! Freight to Australia for just one core (the first in this list) is GBP510 = AUD $911.85 For anyone in the UK who can organise freight or pick up, the core prices seem very fair. -------------------------------------------------------------- Anyway, I've stripped my last core for #4 TX ... a 500VA toroid 115mm OD x 70mm ID x 50mm high So cross sectional area = 11.25sq cm Secondary Turns = 32 Primary Turns = 169 Primary Current = 11.32 A If my maths is correct ... I need a couple layers for the primary ... of 1.45mm (1.65mm sq) = 2 x 6.6A = 13.2A ... or 1.6mm (2mm sq) = 2 x 8A = 16A I have plenty of new 1.45mm and tons of used 1.6mm Could you double check my figures please Tony before I make too many other plans? Thanks. Cheers, Roger |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yup, all looks good Roger. 44v, 169T, 11.25cm = 1.04 Teslas 32/169 x 44v = 8.33v Current density in the wire looks good too. Cheers, Tony. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 885 |
Thanks Tony, I appreciate the doublechecking. So for this smallest transformer ... if I fit the primary first (2 lots of 169 turns) ... The ID will be 67mm, so circumferece is 210.5mm Using 1.45mm wire I will fit approx 123 turns for the first layer if closely wound ... leaving 46 turns to overlap the first layer (with some insulation over the top of the first layer before starting the next) Or do I space the turns out and fit half of my 169 on the first way round ... wind a layer of insulation ... then wind the remainder? Then put a couple layers of insulation and repeat for my second primary winding. I realise this transformer is only producing 8.33 volts ... but the secondary is in series with the 240V AC. Can you explain a bit about where the main potential stresses will be? Thanks. Cheers, Roger |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
O/k we start with a 70mm bare hole, circumference 220mm, and being a pessimist we might get about 80% of that in practice, say 120 turns of 1.45mm wire. Now the final primary winding should leave at least a 50mm hole (70% of 70mm). The build height of the primary can be no more than 10mm if we are to still have a 50mm hole remaining. With 1.45 wire + bulges, plus insulation, 2mm per layer is about the best we can hope for. So five primary layers may just be possible, four dead easy. If we assume ten turns less per layer worst case, then: 1st layer 120 turns 2nd layer 110 turns 3rd layer 100 turns 4th layer 90 turns Total possible 420 turns. And we need two 169 turn windings 338 turns total. So its going to fit very easily. It might come mighty close with three full layers. So that is how I would do it. First layer 120 turns (or whatever will fit). Insulation on top of that, then continue winding on the second layer until you reach 169 turns. Begin the second winding on the second layer, and keep going until layer two is full. Insulation over the top of the second layer, Keep going on the second winding on layer three. It may come close to fitting, if not, place the few extra turns required onto a fourth layer. There will then be three full layers which satisfies the requirements of having the turns evenly around the core. It should work out pretty close, as our original estimate of what would fit was very conservative. As you have pointed out, the two primary windings will never see more than 40v to 50v so the insulation requirement is not great. The secondary to primary insulation will see up to 350v + 50v is theoretically possible. You can pile on the tape over the primary until the hole is 50mm, and be pretty certain to have adequate primary/secondary insulation. Cheers, Tony. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 885 |
That is awesome thanks Tony. Gives me lots of confidence that I'm going about this the right way. I need to make a start on it this weekend. Cheers, Roger |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 885 |
Tony, I have a question about current carrying ratings for our winding wire. I may be wrong but I reckon I saw a post where you said we can allow 4 amps per square mm of wire ... so 1.6mm diameter = 2 sq mm = 8 amps and 1.8mm diam = ~2.5 sq mm = 10 amps While looking for other info I came across a wire sizing chart from CMP Controls where they show ratings based on only 2.565 amps per square mm. See page 19 here ... http://www.cmpcontrols.com/content/CMP-Wire.pdf Do I need to review my plans, or are they just being super conservative? Cheers, Roger |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Acceptable current density in the wire depends on the allowable temperature rise. That limit in turn usually has to do with the type of insulation, and how effectively the heat generated can be dissipated into the environment. As far as transformer winding wire is concerned, there are many different grades of wire suitable for different purposes, and have very widely temperature ratings and limits. There are also many very different applications, such as motor armatures, transformers both large and small, and things that never get hot at all such as tuned circuits and coils on circuit boards. For the "cold" applications, you can buy 105 Celsius rated wire that can be soldered directly without first stripping the insulation. Very nice for making coils for headphones or microphones, but pretty useless for a high power application. The wire manufacturer can have no idea of what you want to use his wire for, or the environment in which it must work, so there is really no way for the wire manufacturer to specify a design current density. The equipment designer is in a much better position to know from experience and testing, and generally accepted practice, what suitable current densities may be. For small and medium sized transformers with fairly exposed windings such as our beloved toroids, 4 amps per mm square is a fairly high but quite acceptable figure. For something much larger, its much more difficult for the heat generated right in the middle of a very deeply buried winding to conduct to the surface, so there may be dangerous hot spots develop deep down, which can be a problem. So a much lower wire current density, maybe 2 amps per mm sq, or even less may be prudent in very large transformers. So really, its a judgement call. Everyone on the Forum seems to have had success with the 4 amps per mm square design figure. Our transformers will get pretty hot at full continuous loading, but I do not know of anyone that has actually had an inverter transformer run so hot it failed (burned out). Cheers, Tony. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 885 |
Thanks for the explanation Tony and the reassurance. Not that I was trying to, but it's hard to argue with experience ... especially seeing so many transformers have been built here. I imagine the manufacturer needs to cover their butt when it comes to listing the various ratings ... plus it wouldn't hurt their bottom line if people buy a couple sizes larger than really needed for a job. The reason for my searching for wire sizes etc was that I visited my scrappee friend yesterday looking for some heavy cable ... and he showed me a roll of stranded insulated wire with the intact label showing 6mm ... but the overall diameter of the insulation would have been lucky to be 5mm ... and the wire maybe 3.5mm ... and I was trying to work out just where the 6mm comes in. I suppose it is the cross sectional area ... but it still doesn't compute for me.  Cheers, Roger |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Wire is often labeled as a mm squared figure, and sometimes with a "wire gauge" which can mean different things in America or Britain, and sometimes directly in diameter. Another measure of wire cross section is "circular mills". One circular mill is an circle of .001 inches diameter. If you look up a wire gauge chart it will very often list several of these All these different units are still in constant everyday use. Cheers, Tony. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 885 |
I do have one of those charts, it was on the wall in my previous workshop. I know I brought it with me when we shifted but have no clue where it is now. Hopefully by using them regularly they'll become a bit more second nature eventually. Just another random question to throw in the works ... I know in reading many of the threads here from over the years ... that if people are using an ozinverter (effectively like their grid) and they add another smaller GTI into the mix ... that any excess power ends up charging the batteries. I reckon I did understand how that works at one stage, but seem to have forgotten. Without muddying up this thread by going too far off track ... would the same thing apply to the Warpinverter? Cheers, Roger |
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