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| Single phase to three phase sinewave converter |
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| MrAl:
--- Quote from: Yansi on January 14, 2019, 01:07:25 pm ---I have already suggested using a suitable microcontroller plus a 3phase power stage. BLDC controllers would not very likely suit, because BLDC is typically (but not always, mind you) driven by square wave. Any smarter controllers than that will likely have numerous feedback loops and it'll become quickly a mess, to make it produce a static voltage in open-loop mode. --- End quote --- Hi, Yeah it could get hairy. Like using two and shifting the phase and AND'ing to get a pseudo sine. |
| CatalinaWOW:
--- Quote from: CatalinaWOW on January 14, 2019, 10:08:05 pm ---Wouldn't a small transformer do the job? --- End quote --- Perhaps a better way to ask the question is this. You show the desired circuit powered by a current tap on one of the phases. Why not do taps on the other two? This at least would provide all three phases properly synched. Amplitude could be handled by designing the taps appropriately, in other words making it a three phase transformer. Additional thought could make it incapable of supplying much more than your required current, though this last step would be a custom transformer and perhaps not the cost effective solution. |
| soldar:
--- Quote from: T3sl4co1l on January 14, 2019, 10:42:29 pm ---So yeah, 3ph is really rare in the US. Evidently it's rare in Spain too; --- End quote --- No, do not get me wrong. It is not rare at all. I could get it "easily" in exchange for large wads of cash (if I had large wads of cash). Let us rewind for a moment. The OP needs very low power three phase supply for some tests or experiments. Someone says he would not have to deal with such "garbage" if he were in Europe where pretty much all households have 3 phase supply. I say that is not so except in the sense that pretty much all households own a Learjet. Yes, if you have the money you can get one but you do not have one now ready to go and you do not have three phase supply ready for me to come over and plug in my three phase motor. If the OP was in Europe he would have to deal with the same "garbage". He would have to go to some small business or shop to find 3 phase power because it would be extremely unusual to find it in a random household. Three phase supply is much more expensive and it makes no sense to supply three phase power to all households. It requires more wiring, more expensive and complicated meters, breakers, etc. It makes no economic sense and I just can't imagine why any country would do it. Now, if I really want to get three phase supply I can get it easily but that does not mean I have it now. I can call the power company, call an electrician, pay a few thousand euros to upgrade the wiring, meter, etc, then sign a contract with the electric company that will cost me quite a bit every month, and I will have three phases right there at my disposal. The thing is that nobody does it because it just does not make economic sense unless your consumption is upwards of, say, 20 or 25 KW. Then yes, it makes economic sense but if you need 3 phase 100W supply every now and then you are better off finding an electronic converter. The restaurant around the corner has 3 phase supply because they need it. They pay separately for active and reactive power. I helped them install capacitors with the fluorescent ballasts because they were paying a lot in reactive power and they did not understand why. All these things are something a homeowner can get himself into if he wishes, it is mainly a matter of money. But most people who have a three phase motor for some machinery find it advantageous to buy a variable frequency drive because it is much cheaper and simpler. So I remain skeptical that any country in the world routinely installs and supplies three phase power to every household. I am not saying it is impossible; I am saying it makes no sense and I therefore believe it would not be done. Now, if someone asserts this is the way it is done in some country I expect it would be easy to provide some evidence (rather than insults). It should not be difficult to find some cites, some videos, some websites, showing how, indeed, most households in such country have three phase meters, three phase breakers, etc. So far I have seen no evidence of this. None whatsoever. Extraordinary claims require extraordinary evidence. Where is it? Maybe in South Kangeronia they supply three phases which rotate counterclockwise and the meters count backwards too and the utility company pays you for the energy you use. It may be true but it is unlikely and I would need to see some corroborating evidence. |
| Zero999:
--- Quote from: IanB on January 14, 2019, 10:57:00 pm --- --- Quote from: T3sl4co1l on January 14, 2019, 10:42:29 pm ---It's my understanding, even if you have a 3ph drop nearby -- say you're neighboring a commercial property that has it -- they still want $10k's to come out and install new hardware, and that's assuming it's allowable at all for, say, zoning reasons? (which I have no idea if that's a thing, but maybe it's part of why). So yeah, 3ph is really rare in the US. Evidently it's rare in Spain too; I've only ever heard it's standard in the rest of Europe, as Yansi has said. I've not visited and inspected their breaker panels myself, I've only seen pictures of them. I don't doubt the veracity of everyone who lives there and says it is in fact available. :) --- End quote --- In the UK there is also a question of danger. Three phase 415 V is considered to be somewhat more dangerous than the normal 240 V single phase supply. You tend to see signs like this wherever 415 V is present inside a panel: This is (probably) not something believed to be compatible with a normal home. --- End quote --- 3 phase isn't that much more dangerous than single phase, since the voltage relative to earth is exactly the same. It's unlikely someone will get a shock between two phases. Yes, three phase is rare in the domestic setting in the UK, but I've heard that in some EU counties it's standard. |
| Simon:
In Italy up to a few years ago 3KW was your limit with extra fees getting you a 4.5KW supply. i don't know if it is still like that. |
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