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Forum Index : Electronics : Chinese Inverter Board - voltage feedback and other ?'s
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| noneyabussiness Guru  Joined: 31/07/2017 Location: AustraliaPosts: 513 |
Oh and there is nothing wrong with EI transformers, they just are not as efficient as toroidal cores, and usually twice the weight for the same power handling... but use what you have... I think it works !! |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Sounds really good. I have never tried an oil filled transformer myself, but looking at the specifications of larger three phase oil filled variacs, and the same variac when run dry, oil jut about doubles the safe continuous current rating. As its maximum safe temperature rise that sets the power limit of any transformer, its definitely something to keep in mind. The latest generation of car automatic transmissions now have a microcontroller brain, but much of the solenoids, control valves and wiring run continuously submerged in very hot transmission fluid without any long term ill effects. Cheers, Tony. |
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| noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 513 |
I used a " 2kw " aerosharp box(ip67 rated box, so watertight, oil tight), custom wound 5kw core on its side... its a beast.. it regularly sees that 5kw too.. Cooling includes the original heatsink on box, and a small pump and cooler in space with board , control gear etc.. hottest oil temp ( i have an arduino with temp readout and fan control) ive seen is 97°c pushing about 7kw on a 38°c day.. its not a work of art like you blokes , but its a work horse... I think it works !! |
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poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1418 |
Hi FFTandMe (is FFT = Fast Fourier Transform?) If I can offer some encouragement, it would be to say by all means build something using the transformer you have. Just learn how it works. Then when you get a different transformer, use that and see the difference. I have built the last 3 inverters using good quality chokes in the primary winding circuit. I view them as the "secret sauce". The chokes absorb the PWM pulses and so prevent high energy pulses coming back to the MOSFETS and destroying them. So, the choke I used in the last 3 is a 2 part choke - 2 in series. I used one of this core and one of these to make a choke. The core is to have a 1mm gap. The gap is important, it allows the choke to operate at relatively high currents and still behave as a choke (and not a straight piece of wire) I make 2 chokes and connect them in series. This arrangement is good for power levels of 3000W and more with a 48V battery. wronger than a phone book full of wrong phone numbers |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
  I keep an eye on eBay for Transformers I seen this one down to $55 last time they List It If you offered them 55 bucks I'm pretty sure they'll take it I'm still not sure where you live so may be helpful maybe not be warned i am good parrot but Dumber than a box of rocks |
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| FFTandMe Newbie  Joined: 11/10/2019 Location: CanadaPosts: 32 |
Hi poida! Yes, you are bang on with the meaning. We owe a lot to Fourier in our daily lives today. He's kind of a hero and I've used the FFT often. Great tool for DSP. I saw that link in the BenandAmber thread and immediately ordered an equivalent from Mouser (I'm in Canada to answer that question too). I also got all the other parts to modify my board at the same time and it all just arrived yesterday. Based on the power levels you listed I'll be happy with that choke. The problem I have with the transformer I have is that its from a microwave, so I'm probably going to have to rewind the core. Add to that that it seems welded together and it adds complexity. I have a ton of 16 gauge (1.3mm^2) enamaled wire on a spool from some amateur radio work (mostly antennas and crystal radio coils; I believe in buying in bulk because "you never know"). I'm toying with making a DIY core and using the tips here to determine the volts per turn. I agree with the approach to get it running. BenandAmber - Thanks for the link. I am toying with that route along with a few others. When I decide which way I go I'll be sure to let you know. |
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| poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1418 |
FFT, how are you positioned with respect to spending a few $$ on a transformer. Maybe obtain a toroid from mouser or even ebay. It could be $100 well spent for a small tranny that will be all you need for testing. (then start looking for a bigger one) The microwave tranny is not a good choice for a core. The laminations are welded together on one or more sides. Sure, it will work, but only for low power levels due to the small size with which you need to get enough turns inside for the secondary. But every tranny you try is a good data point and adds to the collection of experience. The very first inverter test rig of mine used a toy torroidal tranny, 25V @ 1.6A primary with a 240V output. This suited my 48V battery perfectly. And it produced 240V AC in enough quantity to command some respect. Could you tell me the battery voltage you expect to use? Can I presume you want 120V output? Where abouts are you (East/West/North/South) I then will start looking for possible choices. Joseph Fourier was a giant. Not only a Mathematician but he was looking at greenhouse effect back before it appeared as the threat to the world. wronger than a phone book full of wrong phone numbers |
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| FFTandMe Newbie Joined: 11/10/2019 Location: CanadaPosts: 32 |
Hi poida, I'm in a pretty good position for spending money on transformers. The microwave option, while poor for the reasons you and I mentioned, just happened to be on hand. I had contemplated the transformer BenandAmber suggested as well as a toroid from Mouser, but if I'm going to spend a hundred I may as well go with something like this: https://www.ebay.ca/itm/Toroidal-laminated-core-for-AC-power-transformer-3000VA-DIY/174128862663 Its a touch more but I could wind it for experimentation and then when I choose rewind it with appropriate wire to really crank up the wattage. I'm in eastern (maritime) Canada, to answer the other question you asked. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Poida is quite right, give the microwave oven transformer a miss. It would be very difficult to rewind, and the results would be disappointing for the amount of work you would have to put into it. That toriod looks to be very good value and would make an excellent starting point. Cheers, Tony. |
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| FFTandMe Newbie Joined: 11/10/2019 Location: CanadaPosts: 32 |
Thanks. Kinda confirms what I was thinking from the start after I removed it from the unit. I think I'll get that other toroid to start experimenting. Oh, and to answer poida's other question, my system is 24v. At the time I pieced it together (about 6 years ago) that seemed to be the sweet spot of performance for the price as well as parts availability. I may switch to 48v as money becomes available. Not sure though. |
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| FFTandMe Newbie Joined: 11/10/2019 Location: CanadaPosts: 32 |
Thanks. Kinda confirms what I was thinking from the start after I removed it from the unit. I think I'll get that other toroid to start experimenting. Oh, and to answer poida's other question, my system is 24v. At the time I pieced it together (about 6 years ago) that seemed to be the sweet spot of performance for the price as well as parts availability. I may switch to 48v as money becomes available. Not sure though. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
If you need a Transformer I have a few square ones I'm not sure how expensive shipping would be may not be worthwhile to you But I would be glad to give you a Transformer I may have a few other things you could use also  Edited 2020-02-06 15:36 by BenandAmber be warned i am good parrot but Dumber than a box of rocks |
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| FFTandMe Newbie Joined: 11/10/2019 Location: CanadaPosts: 32 |
Hi BenandAmber, Sorry for the delay in reply. My spouse had a major medical event requiring almost 2 weeks in hospital coupled with home care and just thought today about checking in. I appreciate the offer for the transformer but after hearing the toroid I posted is a good candidate for experimentation I bought it. The only question left is: do I use my spool of 16AWG wire and wind a primary just to confirm volts per turn and do some lower power testing, or do I buy some 10AWG wire and maximize the core's potential on the first go? Decisions, decisions... In a related vein, I had my first AliExpress MOSFET scam. Supposedly HY4008s to match what's on my board so I have spares. Markings didn't match spec sheet and Red(on) at 10v measured 110milliohms!!! We shall see how AliExpress handles the dispute as the "seller" is not cooperating. |
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| FFTandMe Newbie Joined: 11/10/2019 Location: CanadaPosts: 32 |
Sorry should have been Rds(on). Phone autocorrupt and all |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
That is up to you, but there is no real reason to experiment as it can all be worked out, and a successful transformer wound first attempt. Inverters generally use a much lower flux density than commercial transformers. For us, idling power is of critical importance, and the recommended design flux density is 1.0 Tesla (10,000 Gauss in imperial). The other thing is that we ideally want to end up with about the same volume of copper in the primary and in the secondary. So when designing a secondary for this, plan to use up no more than than half the full area of the original open hole. Edited 2020-02-20 07:01 by Warpspeed Cheers, Tony. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
I have a few Hy 4008 if you need them warpspeed is not blowing smoke He's probably one of the best in the whole entire world even though he would not tell you this his self It'll blow your mind when you find out Who these people on here are What thay do and have done and what they've accomplished and are capable of You know about poida the great walking me through my build He is just one of the many!!! be warned i am good parrot but Dumber than a box of rocks |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
Like I said before I have a few Transformers and other things like mosfets capacitors If you wanted some parts to experiment around with while you're waiting on your permanent parts It would get you out in the shed and tinkering while you're waiting on parts or trying to determine how you want to wind your Transformer Thank you for your time and have a blessed day Edited 2020-02-22 04:14 by BenandAmber be warned i am good parrot but Dumber than a box of rocks |
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| FFTandMe Newbie Joined: 11/10/2019 Location: CanadaPosts: 32 |
@Warpspeed - thanks for the tips. I'll keep that in mind when I start winding. @BenAndAmber - I ordered some more HY4008's from a reliable supplier. Aliexpress wont give me a full refund so I will be opening a dispute with my credit card company. They want me to send them back but dont want to pay for shipping back. Considering they told me blatant fakes I shouldn't be out a penny on this. As for a transformer, I might take you up on that. My neighbour has a new kid and the last two storms took power out and it made a hardship for them. I was thinking of ordering a 12v version of my board and hooking a transformer to it so they can have something for an emergency they can hook to a car battery or whathave you. Is there a way to private message on here so I can send you details to get an idea of how much it would cost to ship to Canada? |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
 I sent you a private message I have a few other ones also The two that are bolted to the same plate on the left I would guess weight 50 lb Edited 2020-02-24 07:33 by BenandAmber be warned i am good parrot but Dumber than a box of rocks |
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| tytower Newbie Joined: 19/11/2017 Location: AustraliaPosts: 21 |
Just a note for anyone playing with Inverters and boards. I have been able to buy various grid tie inverters by looking on Gumtree in australia . Perhaps Craigslist in US. Some of the older inverters being replaced by bigger systems can't be reused as they no longer pass inspection here . They can be bought for a song if you let the seller know that they can't be legally reused or tested even ! Edited 2020-02-24 08:11 by tytower |
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