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BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961
Posted: 06:10am 27 Apr 2019
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Is the losses so bad when a square Transformer is used as an inverter
I know just plugged into the wall it seems like on some Square Transformers it's very little lossbe warned i am good parrot but Dumber than a box of rocks
PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 651
Posted: 08:16am 27 Apr 2019
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If you GOOGLE something like "advantages of a toroidal transformer" it will go on about smaller, lighter, less magnetic leakage, less noise even easier to mount and that is all true however a conventional transformer will still work but you will lose a few percent in efficiency. Between toroids ans E&I there is/was the C core which was considered to be quite good.
Peter
BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961
Posted: 11:10pm 27 Apr 2019
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PeterB I have read a lot about toroids but was hoping to hear from someone that has used a square Transformer to compare difference and losses
The real world difference in the leakage or idle current when used as an inverter and if it really matters in the end whether it's a toroid or a square
so another words what I'm trying to say here I mean is a square one so bad when toroids are really hard and expensive to find
Thank you very much PeterB 4 taking your time and considering my post
This is the largest Square Transformer I have
Unwound now and setting directly on top of the biggest toroid I have the 52-pound one
As you can see I have not cleaned it up or anyting
it is very dirty but I do have the Old Wire off of it now
I honestly believe that this Transformer would make for a very good low loss inverter
But I could be wrong there are much wiser people on here than I so I'm hoping they would chimed in and set me straight one way or the other
I might just get lucky and have the wise guru himself chime in
according to my amperage meter this Transformer when plugged into wall has a very low idle current
This Transformer seems to be a handmade Transformer
not a factory type Transformer if anyone knows the difference and could tell me for sure I would really appreciate it
Tinker I have still seeing no link or directions where to go to read stories of your adventures on your boat would love to read about it a little bitEdited by BenandAmber 2019-04-29be warned i am good parrot but Dumber than a box of rocks
PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 651
Posted: 12:24am 28 Apr 2019
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Good morning From your drawing the cross sectional area of your core is 6 squ in. Using an old rule of thumb, and correcting for 60 Hz, that indicates 1 turn per volt (roughly). Does that agree with the turns you removed? The core looks a bit like me, old, scruffy etc. so you will be taking a risk and if things go wrong you will destroy some expensive FETs. As you probably know, each lamination is insulated to prevent a current flow across the stack. If that insulation has failed your losses will increase. The quality of the steel is also an unknown. On a different but related subject, I have a question, does the steel in a toroid have to be insulated? I have had a look at the Warpspeed inverter. It is interesting in that a square wave contains all the odd harmonics and this idea removes them by adding equal waveforms in opposition to them. So, if you use a modified sinewave design which has no third harmonic it should reduce the complexity although the 5th would need to be increased. Has anybody tried this? Sorry if I've gone on a bit.
Peter
edit Sorry I forgot the important part. I do not know how well that core will work but if it is in good condition, I would expect the losses to be a few percent higher.
PEdited by PeterB 2019-04-29
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 01:07am 28 Apr 2019
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The whole concept behind this type of inverter is harmonic cancellation in the frequency domain, and filling in the larger steps with much smaller steps in the time domain.
Its just adding directly together the outputs of four simple square wave inverters in the correct proportions to generate a very low distortion sine wave.
Direct digital to analog conversion on steroids.......
The largest harmonic is the third, which measures about -40db below the fundamental, with all the higher order odd harmonics tapering away even lower than that. Total harmonic distortion is around 0.8% without any filtering.
Edited by Warpspeed 2019-04-29Cheers, Tony.
PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 651
Posted: 01:19am 28 Apr 2019
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As usual, I'm behind everybody. However, your waveform is flat and that would be because your added bits are not continuous. According to Mr. Fourier, a square wave contains all odd harmonics and each harmonic is a pure continuous sine wave so you should be adding a pure continuous sine wave out of phase with the original. Using 120 degrees does get rid of the third. O.K. I know , you have already thought of that
Peter
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 01:26am 28 Apr 2019
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This isn't abstract theory, the above waveforms all came from an oscilloscope connected to a working inverter.Cheers, Tony.
PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 651
Posted: 01:45am 28 Apr 2019
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Mr. Fourier is not abstract theory. How dare you? If I am counting your waveforms correctly, the fundamental is on for 120 degrees which clears the third, you then add the 5th, 7th and 9th to produce a very adequate waveform. If those waveforms were continuous, you would get a better output. That's my 2 bobs worth.
Peter
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 02:08am 28 Apr 2019
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Its still a pretty amazing outcome for only four crude bridge inverters, and the residual distortion could easily be reduced further with some additional low pass filtering.
In fact, connecting this inverter to the house wiring significantly flattened out all the fine wiggles. I have no idea why it did that, but the final result is very acceptable.Cheers, Tony.
PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 651
Posted: 02:14am 28 Apr 2019
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It flattened out the fine wiggles because your mains is a very low impedance source. But can I tempt you to think about modifying you design to improve the wave form even more?
Peter
PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 651
Posted: 02:47am 28 Apr 2019
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I think LadyN simulated this somewhere else.
Peter
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 02:52am 28 Apr 2019
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This is what it looks like with a x100 probe poked into the active of a power point. The ripples are mostly gone except just after the peaks, and there is a slight upward sloping flat topping due to many domestic loads having rectifiers that only draw capacitor charging current up near the peaks.
There is also a two stage EMC filter at the inverter that has about a 20Khz cutoff frequency. Don't plan to do anything more with the inverter, but would be interested to hear any suggestions. Edited by Warpspeed 2019-04-29Cheers, Tony.
BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961
Posted: 03:32am 28 Apr 2019
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What do you know the the wise and humble Guru chimed in that may not be a good word guru hope it's not offencive it's not meant that away
And 2 PeterB very close to a turn / volt it was hard to keep track of cuz I was just in a hurry to get it off there
the wire wasn't in real good shape but the best I could tell was about a hundred and ten turns
The Transformer is definitely Pretty Dirty Use this transformer for different things never had any problem out of it
I have forgotten and left it plugged in for weeks at a time and the temperature does not go over the surrounding rooms temperature
I have a name brand laser temperature gun and it can't tell any difference and neither can my finger
I honestly think it's just dirty and would be a good Transformer for years and years to come
I would definitely trust it I tried to take the laminations apart
I did not bend it or nor did I want to bend it and it didn't come easy so I just treated it like a toroid
When I get a chance I'm going to show you a picture of an old Lincoln welder Transformer
I still use every once in awhile this one looks like a brand-new sparkling Transformer compared to it
By the way I'm guessing it was a Lincoln welder because the rest of it was pretty much rusted away
this was dug out of a side of a creek Bank buy a friend of mine
I hosed it out with a water hose let it dry out for a couple weeks
now I use it anytime I need something with a whole lot of amperage it has many taps with many different voltages
Works great I definitely wouldn't leave it plugged in and walk away
but as long as I'm there with it and no kids no neighbors kids no silly Buddies dogs cats any kind of life is around to get into it
I use it and I'm very happy with it
now would I trust this no but my point is these things just keep on workingEdited by BenandAmber 2019-04-29be warned i am good parrot but Dumber than a box of rocks
PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 651
Posted: 04:46am 28 Apr 2019
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That transformer has character! Just be careful. I retired 25 years ago but before that if I needed a transformer I only had to specify it and it would arrive in due course. Eat your heart out
Peter
BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961
Posted: 05:36am 28 Apr 2019
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That is pretty cool I didn't know I was talkin to one of the greats
Do you mind me asking what you used to do Peterbe warned i am good parrot but Dumber than a box of rocks
PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 651
Posted: 05:47am 28 Apr 2019
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Nope! not one of the greats. Just a bloke having fun. I started as an apprentice radio tradesman in 1955. All valves. From 1959 to 1968 as a Technician. All transistors. From 1969 to 1994 as an Engineer. All everything. Early retirement because the establishment I worked for decided there would be no more engineering. I have a mate who makes agricultural equipment and he is kind enough to keep giving me problems just to keep me alive. I am now 81 and probably starting to get dangerous but life has been fun.
Peter
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 09:06am 28 Apr 2019
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You keep on asking that but I have to disappoint you. That website is gone now, They increased the price for the domain too high for me to keep it. The boat will be gone too, soon - if I can find a buyer.
Please no more unrelated questions like that, it is an electronic forum after all.Klaus
BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961
Posted: 12:01pm 28 Apr 2019
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Sorry just dream of mine and u have a boat on your profile pic be warned i am good parrot but Dumber than a box of rocks
BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961
Posted: 12:06pm 28 Apr 2019
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PeterB
My theory of why the world is messed up so bad is no one's listening to the older Generations of the communities they're the ones that have been there done that and have all the wisdom but no one's listening
Or that's what I say anywaybe warned i am good parrot but Dumber than a box of rocks
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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