Single phase to three phase sinewave converter - Page 1
Forum section: electronics / projects

author: sanwal209
author_rank: Regular Contributor
timestamp: January 12, 2019, 10:40:53 pm
content: Hi Guys,Is it possible to convert single phase 220AC to three phase synchronized output. If yes, can you please refer me to some documentation.Best RegardsSanwal Saleem

author: ArthurDent
author_rank: Super Contributor
timestamp: January 12, 2019, 11:30:41 pm
content: There are plenty of DIY methods that work to varying degrees. Google will be a help. The best way is a commercial M-G set like this.http://www.northamericaphaseconverters.com/shop/category/pro-line-rotary-phase-converters/

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 12, 2019, 11:34:47 pm
content: Look up "VFD".

author: Bratster
author_rank: Frequent Contributor
timestamp: January 13, 2019, 12:04:55 am
content: Quote from: sanwal209 on January 12, 2019, 10:40:53 pmWhat do you need the three phase power for? Depending on what your load is there are a couple different options that may work better or worse.For instance if it is just a motor than a variable frequency drive, VFD, will work perfect, as a bonus gives you speed and direction control.But if you need three phase to power something more complex then you probably need a different solution.Sent from my Fi Moto x4 using Tapatalk

author: soldar
author_rank: Super Contributor
timestamp: January 13, 2019, 12:20:42 am
content: https://en.wikipedia.org/wiki/Variable-frequency_drivehttp://www.powtech.cn/en/product-5-1.htmlSearch eBay for Variable Frequency Drive

author: TimFox
author_rank: Super Contributor
timestamp: January 13, 2019, 02:13:21 am
content: Google “Scott-T Transformer”.

author: sanwal209
author_rank: Regular Contributor
timestamp: January 13, 2019, 02:50:45 am
content: Thanks for replies, I appreciate it.We will build our solution. Yes i know VFD but i think it will not help here.i think i didn't ask properly. I am looking for some IC who can drive power stage to generate 3 phase sine wave 220V@100mA while syncing output to the input single ac phase 220V 50Hz.One solution could be to use microcontroller to drive the power stage to generate and sync the output with downgraded single phase voltage with PLL but that will require hefty firmware development. We are looking for some SoC which can handle all this.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 13, 2019, 03:02:39 am
content: Are you perhaps overthinking this? For the very nominal power levels you are requiring the whole sync problem could be handled by generating the two additional phase drivers with a two pole filter selected to get 120 degrees of phase shift, and either another two pole filter for another 120 degrees, or perhaps a separate four pole filter.The rest is just doing the same thing that the VFDs do, generate a DC bus voltage from the input, and then use the control signals to modulate that into your outputs.Does your circuit need to work with both 50 Hz and 60 Hz systems?

author: beanflying
author_rank: Super Contributor
timestamp: January 13, 2019, 03:27:25 am
content: Why go to three phase at such a low power level? What are you needing the 3 phase 100mA supply for?Zero Crossing detection on the single phase is easy to do by itself as a synchronizing point of reference. I have seen some Hybrid IC's (generally much higher currents) around for the 3phase side of it. It might be easier and cheaper to roll your own in your case if you have to stay with AC.

author: sanwal209
author_rank: Regular Contributor
timestamp: January 13, 2019, 03:38:36 am
content: Interesting, So i can feed 220V AC to two separate phase shift filter and get three phase. 100mA is maximum load but nominal load will be around 10mA. So probably this is the simple solution.Yes we do need for 50Hz and 60 Hz

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 13, 2019, 06:17:50 am
content: Doing both frequencies will require either a compromise, or switches. If you tune your filters for 55 you will have a few degrees of phase error at both frequencies. Only you can say if that is OK. Similarly you have to understand your application to know if this simple approach will work

author: soldar
author_rank: Super Contributor
timestamp: January 13, 2019, 09:12:39 am
content: Quote from: TimFox on January 13, 2019, 02:13:21 amI googled and foundQuoteSince the 1890s are long gone and two-phase systems have not existed since then and, in any case, the OP has only a single phase, I cannot see how this could be used in a solution.

author: soldar
author_rank: Super Contributor
timestamp: January 13, 2019, 11:04:13 am
content: One way to generate three phases equally spaced 120º apart is to use a divide by 12 counter and use logic gates to switch the outputs. I have not used this technique for three phase generators but I have used it for single phase variable frequency. By using counter/divider logic the phase will always be perfect no matter what the frequency.

author: capt bullshot
author_rank: Super Contributor
timestamp: January 13, 2019, 11:25:23 am
content: http://wunderkis.de/pwramp3/index.htmlscroll down to "Input related stuff" - all analog.

author: station240
author_rank: Unknown
timestamp: January 13, 2019, 01:33:51 pm
content: I built this circuit to trick a machine with 3 phase input into thinking it was connected to 3 phase, when only 1 phase was available.Does work for that purpose, uses the phase shifting ability of capacitors.https://www.homemade-circuits.com/2013/09/three-phase-signal-generator-circuit.html

author: duak
author_rank: Super Contributor
timestamp: January 13, 2019, 07:35:25 pm
content: Generating 3 phase from 2 phase quadrature is quite easy. It can be done with transformers as in the Scott-T transformer. Looking at it you can see that the B & C phases are basically the A phase with the Q (quadrature) phase either added to or subracted from it. This can be done with opamps and resistors which can then be used to drive some power electronics.Generating 2 phase quadrature over a frequency range is not as easy but is possible. An allpass filter can be used to generate a phase shifted signal with a particular phase at a particular frequency. Allpass filters can be combined to provide a constant phase shift over a range of frequencies:https://www.edn.com/electronics-blogs/living-analog/4375814/All-pass-filter-phase-shifterTo generate just Q for a 50-60 Hz frequency range, I think that only two stages of one chain will be needed rather than the four stages in two chains shown here.I also think there is an error in the schematic in that resistors R5 to R8 should be exchanged with the capacitor to the right.Hope this is clear,Cheers,

author: soldar
author_rank: Super Contributor
timestamp: January 13, 2019, 07:54:25 pm
content: Quote from: duak on January 13, 2019, 07:35:25 pmWell, yes, of course. Once you have two signals with different phases you can combine them into any number of phases with any phase offset you choose. That is how vectors work. If you have two or three phase you could combine them to form 5 or 7 or 9 or whatever you wanted.The problem is that nobody today has a two phase (90º) supply. If they have more than one phase then they will have three phase (120º).

author: Zero999
author_rank: Super Contributor
timestamp: January 13, 2019, 08:02:29 pm
content: Yes, I think a couple of people here have misread the original post. Here it is again, with the relevant parts highlighted.Quote from: sanwal209 on January 12, 2019, 10:40:53 pmThat's single phase, not two phase, to three phase conversion.I think a rotary converter is probably the easiest solution, especially as it's only low power.

author: Yansi
author_rank: Super Contributor
timestamp: January 13, 2019, 08:07:23 pm
content: What are your exact requirements?Making a three-phase inverter bridge with just fixed output voltage (no current feedback) is so easy. Even adding the synchronization (if you that much need the 3ph output synchronised to mains) would come to just one PI regulator to tune.All could be done with something as simple and as small ashttps://www.st.com/resource/en/datasheet/stgipn3h60.pdfcontrolled by even Attiny261 (any MCU with a three phase PWM timer). Sinewave output could be filtered out of the PWM using suitable LC low pass filters.So what do you need a 220V 3ph 100mA supply for?

author: duak
author_rank: Super Contributor
timestamp: January 13, 2019, 09:14:33 pm
content: I know that 2 phase power does not lay thick on the the ground. It's my bad for not tieing it all together by pointing out that the 2 phase quadrature is derived from the single phase input by using allpass filters to implement a phase shifter then simple networks to generate the B & C phasors that could drive a power stage as per the OP's second post:"i think i didn't ask properly. I am looking for some IC who can drive power stage to generate 3 phase sine wave 220V@100mA while syncing output to the input single ac phase 220V 50Hz. "I think the circuit could be implemented with one quad opamp and a handful of Rs & Cs.Cheers,

author: Yansi
author_rank: Super Contributor
timestamp: January 13, 2019, 09:25:33 pm
content: Forget analog filters. It won't be precise and stable enough, not really something botched up from a quad opamp package. But still, I haven't noticed you specifying the purpose of this 3ph generator, so hard to judge if that would suffice or not.Even if you could produce three sine waves 120 degree apart using few opamps, whats your plan of amplification up to 220Vac? This analog solution just does not make much sense. The digital route is definitely easier one.You may probably findMC3PHACintegrated circuit. Which if I remember correctly is some preprogrammed 8bit MCU or what. Very expensive, probably very obsolete too. But can produce 3ph PWM to drive a power stage, and probably could be frequency locked on the mains, using some external circuitry (PLL like a 4046).

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 13, 2019, 11:41:59 pm
content: Quote from: Yansi on January 13, 2019, 09:25:33 pmThis all hinges on what the purpose and requirements are. Stated requirements are 220 V AC single phase in, 220 V AC three phase out with 20 mA supplied and phase synchronization.An analog solution that achieved fractional degree phase alignment while supplying 220 +/- 1% output voltage would be complex and unwieldy at best. Digital approaches are likely to be far better, but I can make no meaningful recommendations on IC's.One that achieves phase within a few degrees of correct with outputs set at a nominal round 170 VAC might be suitable to purpose and is almost trivially easy to implement.It all depends on what the "real" requirements are. These dark corners of specifications are always where confusion lies and frequently leads to overdesigns, or underperforming designs.

author: Yansi
author_rank: Super Contributor
timestamp: January 13, 2019, 11:44:20 pm
content: I have asked few times here, what the real purpose and requirements are. Still waiting for the response.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 13, 2019, 11:54:53 pm
content: Quote from: TimFox on January 13, 2019, 02:13:21 amNot from single phase though!Also, not the US's "two phase" or "split phase", because the phase shift there is 180 degrees. In linear algebra terms, it's linearly dependent.The traditional methods, as mentioned, are a rotary phase converter (uses a spinning mass to generate the rotating phase sequence), or a VFD (synthesizes phases directly, with a controller).If the load is a motor, the third phase can be generated in situ (with a capacitor), if you don't mind that the starting torque is low and the maximum output is reduced (about half, I think?).If the load is a rectifier (lots of industrial equipment, e.g., VFD, welder, etc.), it doesn't much matter how many phases it's powered by, but you may need more filter capacitance on the supply, and the power factor will be poor, which is a big pain when it comes to the already low capacity of US outlets.Tim

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 12:04:39 am
content: I am not sure, but I think most (if not all) commercially available rotary converters will not have the output synced to the mains input and will provide slightly lower frequency? (unlikely to have both synchronous motor and synchronous generator inside).But I am not sure, how these are really made in the US, as we do not have to deal with this garbage in central EU. (3ph present in almost if not every household).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 14, 2019, 12:13:17 am
content: It's same frequency.Shifting frequency is actually really hard to do, electrically! If you needed, say, mains at 50Hz, you could use a synchronous machine with the stator driven at 60Hz, rotating it at 10Hz (600 RPM) via gearing from a normal (synchronous) motor, and taking 50Hz off the rotor. Otherwise, a motor-generator set, or these days, using a VFD.Tim

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 12:45:45 am
content: Doubt that rotary converters use synchronous motors (difficult to start), or that they use gearing to correct for the slightly under-synchronous speed of the induction motor. Because I think there is no need to correct for the slightly lower frequency in the first place.The will very likely be a induction motor and synchronous generator on a single shaft. Hence the output frequency MUST be slightly lower, due to the slip of the induction motor.Gearing is added cost, complexity, noise.Synchronous motor is a problem to start up, not to mention I haven't seen a single phase synchronous motor bigger than a couple of watts.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 14, 2019, 02:22:05 am
content: No, rotary converter doesn't fall out of sync. How could it? Two of the three phases are supplied directly by the mains input! The rotating mass is only there to supply the third phase. Do you mean the third phase has a frequency shift? But then its phase would be rotating relative to the mains, and a rotaryphaseconverter it ain't.The field in the rotor does slip, but it slips relative to the rotor itself. That field, as seen by the stator, is rotating at mains frequency. Slip manifests as a phase shift, not a frequency shift. The phase shift won't be exactly 120 degrees, but a bit more because of the slip. AFAIK, reactance dominates, so you need compensation capacitors anyway, and you probably can't measure this phase shift in operation, just under contrived circumstances (no load?).Perhaps you're having a confusion similar to the "missing dollar paradox"? In that one, the listener is misled to subtract quantities when the correct step is to add; in this case, the slip might be there, but it subtracts back out when you look at the field seen by the stator.Tim

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 02:55:00 am
content: What if you would try to first state what kind of electric machine the converter is, instead of insisting that i am not right (i think i am pretty spot on with those induction motor driven generators in the isolated converters)? I haven't noticed once you specify, the usual non-isolating rotary converters use an induction motor directly as a generator for the third phase? No other machine is present on the shaft.Without stating the basic concept, we could argue over and over and both be correct.But thats no problem, I have already done a bit of research and informed myself.So, cheap rubish uses specially wound* 3ph induction motors fed by a single phase using the remaining leg as the third phase.*to acomodate for the higher current in the input phase and the output voltage assymetry.Then it makes sense.God bless those with (and without) 3ph available!//EDIT: Typo.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 14, 2019, 04:52:32 am
content: Ah hm, I thought this was the only kind but if there are others I'm not aware, that would be a problem!http://www.phase-a-matic.com/images/Rotary-Converter-Connection.jpgWhere "rotary converter" is just an induction motor (no load) with capacitors as needed.Or, better yet, this:https://electronics.stackexchange.com/questions/280486/diy-rotary-phase-converter-with-starter-motor-cutout-relay-in-parallel-with-loaAn "isolated" converter that is literally no more than a genset would indeed require a synchronous machine to produce synchronous output, and one made from induction motors would... hmm, I'm not sure offhand which way the field slips in generator mode actually, but that's rarely used anyway, so, a pair of sync machines it would be.Cheers!Tim

author: capt bullshot
author_rank: Super Contributor
timestamp: January 14, 2019, 06:34:40 am
content: Just a hint across the pond:In Europe, a "rotary converter" in general refers to a Motor-Generator set on the same shaft. Could be anything including DC / single phase AC / induction / synchronous and even different frequencies.I had read about the Uncle Sam style "rotary converter" before, there's no such thing here.

author: MrAl
author_rank: Super Contributor
timestamp: January 14, 2019, 11:47:05 am
content: Hi,Back when i worked with a power converter company we used our own special designs to do single phase and three phase low distortion sine converters. We were able to get high efficiency and very low distortion.The main idea is to use a three phase bridge circuit with PWM. The PWM comes from a controller board that generates the signals alone with driver boards that drive the main transistors of the 3 phase transistor bridge. Power levels could go up to 30 kilowatts.I see your power requirement looks low however. Maybe you could look into 3 phase brushless motor drivers.You can also type in "Three phase controller chip" and get some links to look at.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 01:07:25 pm
content: 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.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 01:14:37 pm
content: Quote from: T3sl4co1l on January 14, 2019, 04:52:32 amIn an asynchronous generator, you would need to up the speed above the synchronous speed, to obtain the synchronous frequency.Induction generators are used too, not that often, but nothing that special. You just connect a typical induction motor to the mains and then drive it above the synchronous speed, where you put it in a negative slip ratio, which is the generator mode. (Slip ratio above 1 is a braking mode).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 14, 2019, 04:49:46 pm
content: Negative slip, of course! It would need gearing to account for two slip's worth.Tim

author: soldar
author_rank: Super Contributor
timestamp: January 14, 2019, 05:15:09 pm
content: Quote from: Yansi on January 14, 2019, 12:04:39 amReally? Where is this? What city and country is it that "3ph present in almost if not every household"? I am curious.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 06:31:51 pm
content: Germany, Poland, Austria, Czech Republic, Slovakia, (probably even others) all those very likely have 3ph present everywhere. haven't seen a single 1ph distribution transformer anywhere in my entire life. Always 3ph, always 3ph wiring, either cables in ground or hanging on the poles.Small flats tend to be connected only single phase (due to small power requirements), but to get three, you just pay few bucks more to get the electricity meter change out to 3ph, three phase low voltage power is readily present in the incoming distribution cabling.

author: soldar
author_rank: Super Contributor
timestamp: January 14, 2019, 06:44:22 pm
content: Nonsense. I have traveled and lived in Europe, USA, Asia, etc. and there is no country in the world where there is "3 phase supply in almost every household". I do not know where you live but there are people from many countries on this board who, I am sure, will confirm what I am saying.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 06:52:33 pm
content: No, you do not know nothing, bro. Can you give example, where in Germany, or for example CZ is a place, where there is not 3ph available?Having a 3ph available in household does not mean you have a 3ph outlets placed in your living room.And as a plain tourist, you won't likely ever see how stuff is wired here.

author: soldar
author_rank: Super Contributor
timestamp: January 14, 2019, 07:15:41 pm
content: The notion that anywhere in Europe, indeed anywhere in the world, there is "3 phase supply in almost every household" is ludicrous. Saying it is "available in every household" means it is already wired and installed. That is nowhere true. If by available you mean you can pay to have it wired and delivered then that is just as true in America as it is in Europe. I do not know what idea you have of America but I assure you they have 3 phase over there too. At least they did in the parts where I lived.I travel in Europe regularly for business and pleasure and I know what domestic "household" installations are like in most European countries. In fact I was in Prague just some months ago (lovely city BTW) and stayed at an RB&B and exchanged some conversation with the apartment owner about some wiring problem he was having in the bathroom where he had installed a clothes washer in a less than perfect way.Again, maybe posters here from other countries can confirm or deny.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 07:22:54 pm
content: Do you have problems reading a text or what? I have written a CENTRAL EU.The countries above mentioned (DE, AU, CZ, PL, SK) are pretty much what CENTRAL EU is about. And I am pretty sure I am correct with what I have stated.Quote from: Yansi on January 14, 2019, 12:04:39 amAnd no bro, your interpretation of written text is again incorrect. All distribution is done in 3ph. No single phase transformer for distribution are being used. Any point you can connect a house to, has a 3ph power available. Having installed only a single phase meter is just cost optimization for low power demands, where 3ph would not justify.But the cable into the house from the power company is always 3ph power, without an exception. The meter is the last thing the power company owns, the rest is a problem of the house owner.Please specify where exactly have you stayed, I will gladly check whether three phase distribution is available at the panel.//EDIT: Maybe you just do not understand the difference: In the US and most Anglophonic countries, distribution is done in SINGLE phase ONLY, and there is NO way to get wired a three phase power in, even if you would like to. Unless you are willing to pay the power company to build those 5 miles of wiring to your house.Changing a single ph to 3ph for a household in central EU means just having the power meter replaced!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 14, 2019, 07:37:29 pm
content: Difference in detail. Single phase distribution exists for local areas (like where I live currently), but unless you are really rural the distance to a 3 phase source is much less than 5 miles. In my case it is about a half mile (one kilometer) to 3 phase power. It still is not economical to bring that in. Hence the market for VFD and other converter technologies.I am sure that it is hard to generalize about this to entire regions or countries. Lucky for you that you live where 3 phase is available. Who knows whether the money spent on that has held back your economy in other ways?

author: IanB
author_rank: Super Contributor
timestamp: January 14, 2019, 07:40:49 pm
content: Quote from: soldar on January 14, 2019, 07:15:41 pmIn the UK, domestic low voltage power distribution is almost universally produced by utility transformers as three phase, 240 V / 415 V wye (three phases plus neutral). The normal arrangement is that each dwelling gets one phase plus the neutral at 240 V with typically 100 A or maybe 200 A service. Farms, commercial premises and small businesses may have all three phases inside the building, though still usually distributed and used as single phase supplies. Therefore the typical domestic household does not have access to a three phase supply, however light industrial users can have such access for heavy machinery.In many parts of continental Europe I understand that domestic dwellings may have three phase service as standard, with perhaps 60 A per phase. Normal outlets get just one phase at the nominal 230 V, but power hungry devices such as water heaters, central heating or ovens may use all three phases. Since every country in Europe has different supply standards this may vary depending on which country is being considered.

author: soldar
author_rank: Super Contributor
timestamp: January 14, 2019, 08:03:02 pm
content: Again, "3 phase supply in almost every household" is just not true anywhere. Installing it means paying for wiring, meter, etc. To cite that as a solution to someone who is asking about needing 3 phase, 100 mA supply is just ludicrous.In Spain, new detached, single family homes, usually get 230volt and around 60 Amp service which is almost 14 KW and should be plenty enough for most homes. I suppose you could get more amps if you needed but that means a much more expensive installation and most homes simply do not need it. Now, I am sure that if you have special needs you can get three phase service but it is far from being "every household".I participate in a Spanish forum for machinery and machinists and only people who have business shops with machinery would have three phase supply. The rest who have small shops in the homes or garages all use variable frequency drives for their three phase motors because getting three phases delivered is just too expensive and out of the question.I am willing to be corrected if someone comes here and posts "I live in city X, country Y, and here all residential households have 3 phase supply as a matter of course". I would like to see that because it would be very, very, unusual.

author: IanB
author_rank: Super Contributor
timestamp: January 14, 2019, 08:07:35 pm
content: Quote from: soldar on January 14, 2019, 08:03:02 pmSomeone will come along and tell you that it is true where they live. It may not be true in Spain, or Britain, or France, but I have been told it is true in central and eastern parts of Europe. In such places every home has three phases at the switchboard and big appliances like heaters use a three phase supply as standard. You may not believe it, but that does not mean it is not true.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 08:24:09 pm
content: Why are you again putting in my mouth something I haven't said? Are you troll or dumb or what? Could you please take the time and point me to the place, where I have offered as a solution to the OP, to get a 3ph power to his house?And again and last time, I am clearly stating, that to obtain a 3ph here, you just need a meter change-out, You will NOT pay any extra wiring (except your own side to the 3ph appliance), 3ph power is already and always present at the place of the meter.Detached houses in central EU do have indeed 3ph power available, and even more often used than just flats, as typical mountain cottages uses 3ph for heating, water pumps and even for cutting firewood. In flats, the 3ph is used sometimes also for heating and for example electric cooking stoves.Okay, then leave your singlephase in Spain, nobody in central EU could care less. 14kW you say? That would be a nice 3x20A supply in here. That means you (in Spain) have about 2x 16mm square wires. Impressive. We need just 3x 2.5mm square for the same 14kW. You are probably smart enough to figure out, if 3ph power into remote household makes sense, aren't you?But you can still be an non-believer, as you wish. No wonder that you are stuck with single phase, if people think like you.

author: soldar
author_rank: Super Contributor
timestamp: January 14, 2019, 08:40:20 pm
content: Ok, I will wait for someone to come in and say "I have three phase supply in my residential home as do all the homes around me and I am located in such and such place". In the meanwhile I stand by what I said. It is not true that"in the countries above mentioned (DE, AU, CZ, PL, SK) 3ph present in almost if not every household". Not true at all.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 08:45:49 pm
content: Unfortunately for you, it is true. Please continue living in Spain and leave this thread.You have probably not once put any useful information in this thread, you seem to be just trolling for whatever reason. Continue doing so, you will probably get reported.

author: soldar
author_rank: Super Contributor
timestamp: January 14, 2019, 08:52:26 pm
content: Quote from: IanB on January 14, 2019, 08:07:35 pmWell, I am not saying it is somehow impossible, I am saying I have not seen it. And he saidQuote from: Yansi on January 14, 2019, 12:04:39 amwhich is hogwash. He is talking like the US is some backward water compared to Europe where we all have 3 phase supply at home. I am willing to bet that only a very small percentage of homes in Europe have 3 phase supply.

author: sanwal209
author_rank: Regular Contributor
timestamp: January 14, 2019, 08:58:47 pm
content: Sorry folks for late reply, I had fever.Let me write down brief requirements. So We developed a device which does testing coils of diesel generator. While testing there is a point when generator have to be off due to certain requirements and to continue testing we need to feed 3 phase AC to the coils of generator. Attached is rough block diagram.Problem is we dont have time to develop inverter which is controlled by micorcontroller. it will require alot of firmware development. Our best bet would be a SoC or IC which takes downgraded mains supply and generates 3 phase output which is synced with input mains.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 09:25:59 pm
content: Because you have not seen something, does not mean that it is not true. Especially if someone, who lives there (you do not and hardly to believe you ever did) for his whole life, has formal education and a degree in power electronics and is professionally qualified (although for not so long) to work on mains installations and appliances, should know better than you, how mains distribution and networks look here like?And yes, I insist upon what I have said. The need for rotary phase converters is completely unheard of here. And also yes, the distribution of electric power and the general technical level of electrical installations in the US is way behind what is available and commonly used and done in the central EU (but it seems, it is also valid for Spain?).Please accept that as a fact. No offense, just stating facts. You just seem offended, that I use stronger language, when calling out things with names. But please rest assured, that I do this regularly, independent of the topic. You may like it or not, but please do not try masking your nonexistent arguments behind me using a strong language to call things out.The only rotary converters that has been in wide use in our country (and very likely all our neighbors) and some of them are still in use, are ward-leonard type of drive systems, which are mostly used for quite different tasks, than making 3ph from 1ph.Even IanB has told you, that central/east Europe uses 3ph as a standard, but you just seem to selectively ignore that.Now I will ignore YOU because we have already made enough mess in this thread, and I am not willing to deal with people like you (who know everything and been everywhere) any longer.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 09:29:41 pm
content: Quote from: sanwal209 on January 14, 2019, 08:58:47 pmThank you for the image and sorry for the mess in this thread.Could you please explain the process, in which you feed 3x220V into the generator coils? What is it supposed to do? I can't figure out which test would need a very weak (100mA?) threphase synced supply.Do you test the control electronics with it (hence just the small current required)?

author: sanwal209
author_rank: Regular Contributor
timestamp: January 14, 2019, 09:47:18 pm
content: We only want the control boards to think that there are voltages present on the coil. We only require small current for it.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 14, 2019, 10:08:05 pm
content: Wouldn't a small transformer do the job?

author: sanwal209
author_rank: Regular Contributor
timestamp: January 14, 2019, 10:09:11 pm
content: Transformer how?

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 10:10:07 pm
content: So in fact you will not feed any coils, just the measurement circuit, then small current will suffice. I have just wanted to be sure I understand your intention correctly.Do you know how clean (THD, upper harmonics) the signals should be? What is the limit, what is still usable for the test?I think unfortunately, that the digital solution may still be the easiest one. There is not much code that is needed to make a threephase inverter bridge to produce the voltage and to sync it to any other signal.However, I think you could probably still make it happen in good old analog fashion. I have remembered, that one of my friends have built some fully analog controlled VFDs, so I have asked him if he could share the schematic of the 3ph VCO, and sure enough, here it is!There are four OTAs used (2x LM13700, still should be available) and the frequency is voltage controlled.Use the VCO input together with a PLL, for example a 4046 to lock the frequency of this to the mains input.The output amplitude at the RST terminals should be stable, due to the AGC (on the left). The phase stability and accuracy is given by the timing capacitors - all must be the same in capacity and stable in temperature. (Use good quality foil types)Then use three analog amplifiers, something like TDA2030 to drive three small step-up transformers, to up the voltage from those few volts up to the desired size.I think this analog amplifier + step-up transformer solution will have the advantage of producing very clean outputs, and is probably good enough for some tens of watts of output.I can't think of anything simpler than this. It is just a couple of OTAs, the PLL and three power amplifiers, plus the three output transformers. (Just use backwards connected small mains transformers)

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 10:18:30 pm
content: In principle, the circuit above is an oscillator with a three phasing RC filters, except that the R part is created by the OTA, which serves as voltage controlled resistor.Each RC circuit provides 60 degree of shift, 180 degree the whole loop (oscillates). That's why there is the inverting amplifier to obtain the third phase, which is 60 + 180 degree away, to make the third phase of 240 degree shift.

author: sanwal209
author_rank: Regular Contributor
timestamp: January 14, 2019, 10:23:02 pm
content: Indeed its a good solution. I was thinking about another solutionMains AC 220 -> 5V -> Buffer -> 120 Phase sifter -> 120 Phase shiftier -> TDA2030 -> Step Up Transformer| || |__ TDA2030-> Step Up Transformer|__TDA2030-> Step Up TransformerIt will be more simple and we dont need PLL right?

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 10:26:36 pm
content: I think crating 3x 120 degree shift is not that easy, as 3x 60. You will in the end need probably more active parts in the circuit, than in the diagram above.Also your solution will provide incorrect phase outputs, if the mains frequency gets offset away from the nominal, where the phasing networks have been calculated. I think the solution with 3x 60 degree loop will be more robust and not frequency dependent (i.e. less phase error).If you change your mind you want to test 50 or 60 Hz system, you won't need to change all phasing networks. The PLL will just lock at different frequency and the output phase relations will be still correct.I am not sure, why are you afraid of a PLL. I think PLL is easier to implement, than to wrestle three 120 degree phasing networks.My solution IC count: 2x LM13700, 1x opamp, 1x 4046 (or other similar device), plus 3x some monolithic power amp. I don't think it is that bad.

author: sanwal209
author_rank: Regular Contributor
timestamp: January 14, 2019, 10:36:19 pm
content: I simulated in Tina, Have a look at the attached schematics and Waveforms.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 14, 2019, 10:42:29 pm
content: Quote from: CatalinaWOW on January 14, 2019, 07:37:29 pmIt'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.Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 14, 2019, 10:44:32 pm
content: Quote from: sanwal209 on January 14, 2019, 10:36:19 pmLooks nice.I don't suppose you can take a close look at the control and see what it's sensing? If it doesn't matter what frequency or phase each of the inputs is, you don't need a phase shifter at all, just wire them up straightaways!Tim

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 10:48:51 pm
content: I would not consider this solution.it is: 1) fixed frequency only 2) you need a lot of precision parts, or trimming respectively, to reach satisfactory level of phase balance. Don't forget precision foil caps are rare, and a typical resistor is 5 or 1%.I think the solution with OTA providing correct phase at all frequencies without the need for tuning the phasing networks, is better. More bang for the buck. My solution just needs the caps to be the same value. It is likely easier to find three caps of the same value, than to find and select some specific value (or to trim the resistors in circuit).You would need to align both allpass filter branches to obtain correct phase and amplitudes. The three phasing RC 3x 60 degree are self-aligned, always at 60 degree each to make the 180 degree shift to start oscillation.Or have I missed st.?

author: IanB
author_rank: Super Contributor
timestamp: January 14, 2019, 10:57:00 pm
content: Quote from: T3sl4co1l on January 14, 2019, 10:42:29 pmIn 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.

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2019, 11:07:00 pm
content: That is the leg-to-leg (phase-to-phase) voltage.We have 400V leg-to-leg, and 230V (any)leg-to ground. Nothing special really, for any extra warnings to be present. (so for the British 240V, a 415 is the correct leg-to-leg voltage). That is just normal voltages one has to expect, when poking his fingers in switchboards.The load from the house is split equally (at least in theory) across the three phases, as each phase-to-ground voltage is the standard 230V (+-10%).Only the large power hungry appliances work with all three phases, to be able to see the phase-to-phase voltage. (There are also exceptions, some appliances use just single 400V input and are connected in between two phases, typically some industrial power supply modules and for example some welders use 400V single phase input - although typiccaly having a three phase plug, but only two phases used as a single 400V).

author: MrAl
author_rank: Super Contributor
timestamp: January 15, 2019, 12:51:44 pm
content: Quote from: Yansi on January 14, 2019, 01:07:25 pmHi,Yeah it could get hairy. Like using two and shifting the phase and AND'ing to get a pseudo sine.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 15, 2019, 01:56:56 pm
content: Quote from: CatalinaWOW on January 14, 2019, 10:08:05 pmPerhaps 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.

author: soldar
author_rank: Super Contributor
timestamp: January 15, 2019, 04:11:17 pm
content: Quote from: T3sl4co1l on January 14, 2019, 10:42:29 pmNo, 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.

author: Zero999
author_rank: Super Contributor
timestamp: January 15, 2019, 04:28:09 pm
content: Quote from: IanB on January 14, 2019, 10:57:00 pm3 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.

author: Simon
author_rank: Unknown
timestamp: January 15, 2019, 05:40:22 pm
content: 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.

author: soldar
author_rank: Super Contributor
timestamp: January 15, 2019, 06:22:06 pm
content: It is interesting to know how many of the standards we have today are the product of evolution. You can pick any standard device and think it is badly designed. British plugs, NEMA, Schucko, all have their cons and maybe you can find something if their favor but they all emerged like that for their own reasons. One thing I do not like about Schucko is that it is not polarized but the Wikipedia explains why. I also don't quite like the Earth contact system.At any rate, in Italy they used to have different rates for lighting (luce) and for motor power (forza) and they had different plugs. Of course one of the most common items was a plug converter which allowed using cheap electricity for lighting.https://en.wikipedia.org/wiki/File:ForzaLuce1950.jpgEven though I have never seen it personally it used to be the same in Spain and a carryover from all that is that, even though today they are connected to the same meter and pay the same rate, circuits are either for "lighting" (luz) or for "power" (fuerza) and those circuits have different requirements. Lighting does not require protective earth while power does. I find it stupid. And also, as a carryover from those old times a thingy which allows three plugs into one socket is called an "electric thief", just like in Italy. You can search Google images for -ladrón electricidad- (electricity thief) and see what I mean.I have a theory that the design of the BS plug was so big so that it could be used as a boat anchor in an emergency.

author: soldar
author_rank: Super Contributor
timestamp: January 15, 2019, 06:34:10 pm
content: Getting back to the OP, it would not be too difficult to design a three phase signal generator, even of variable frequency, followed by three linear audio amplifiers. I think this would be an interesting project.This might practical up to, say, 50 or 60 W per channel. Once yo get into some real power the linear amps are going to be dissipating some real heat and a switching amp would make more sense.I can't see a real need for a low power three phase source but it would be an interesting project.

author: capt bullshot
author_rank: Super Contributor
timestamp: January 15, 2019, 06:59:33 pm
content: Quote from: soldar on January 15, 2019, 04:11:17 pmI don't own a Learjet, but just because I don't have enough space to build the appropriate hangar on my propertySo this is the panel in the basement, and the three-phase outlet in the basement. There's another one in the garage. The cooker / oven in the kitchen has a three-phase feed. It's been there when I bought that house, so no excuses I might have installed that just because I've wanted that. Anyway, if I would walk (I won't do that) to a random neighbor and ask him to show me his / her panel, it would be a three-phase installation like mine. Mine's quite a modern one, with an additional (single phase) meter for the solar installation, but older ones look similar, often you find a mechanical (Ferraris wheel type) three-phase meter. Very old ones have a single phase meter, but a three-phase feed available at the panel, one just has to ask the utility to replace the meter. There's no single phase distribution here at all. Even in e.g. a two-room rented flat it's normal to have three phase power at the breaker panel with a three-phase meter installed.Other countries have other standards, for sure.Edit: added a random (images search found) picture of a typical (old style) household distribution line (four wires, three phase). You won't find these anymore since they buried the cables under the streets in large scale some ten years ago.

author: MrAl
author_rank: Super Contributor
timestamp: January 15, 2019, 07:01:54 pm
content: Hello again,Quick note...Around this area we mostly see 3 phase power systems in industry.Yeah i think anyone can get it but it will cost much more than a standard home bi phase service (USA).

author: soldar
author_rank: Super Contributor
timestamp: January 15, 2019, 07:52:38 pm
content: Quote from: capt bullshot on January 15, 2019, 06:59:33 pmOK, this is interesting. I can't see the photos well so I will just take your word for it. Is this general use in all of Germany? Even what used to be Eastern Germany? What is the amperage or power available at the panel? Is the range/stove water heater or other appliances three phase? It would be interesting because I have never seen three phase appliances sold here. Part of it is that we have very expensive electric rates and using gas or other fuel is cheaper.I mean, if they wanted they could build every home here with the panel already prepared and wired for three phase but it saves a little money at building time and it means a lot more cost to retrofit. Like so many other things. I would like to have cat5 ethernet cable in every room but it would cost me a fortune now to install when it could have been done at new construction for very little.

author: capt bullshot
author_rank: Super Contributor
timestamp: January 15, 2019, 08:27:25 pm
content: Quote from: soldar on January 15, 2019, 07:52:38 pmIt's general use in Germany, but I don't know what was the standard in former Eastern Germany was. For sure, everything gets adapted to the Western Germany standards there over time. So it's perfectly possible to find older installations that aren't updated to modern standards.At this particular panel, there's 22kW available (3x 32A). Afaik, this is the common standard for a household. If one uses electric heaters, up to 3 x 63A (43kW) can be installed. But usually we have Gas or Oil for heating.There are small boilers (2kW), single phase pluggable into a standard socket, and larger ones (three-phase, up to 24kW) commonly available. In the kitchen, there's a three-phase wire junction box for the cooktop and oven available (also common standard). Cooktop / oven combinations have a three-phase input but can also be wired for single phase usage. At older houses, the kitchen cooktop installation can be quite confusing for the beginner, since the three-phase junction box wasn't standard back then.I have retrofitted Cat5 installation here myself, didn't cost a fortune at all, but had to be done at the right time (e.g. while renovating a room).

author: soldar
author_rank: Super Contributor
timestamp: January 15, 2019, 08:57:36 pm
content: Now that I think about it, I was recently reading a thread in some forum, I don't remember where, where some guy was asking about connecting some heater which could be wired for three phase or for single phase and he was doing it all wrong. I do not remember the country. I assumed it was some industrial heater but now I wonder if it might have been a domestic thing.I was assuming the price of electric power in Germany would be relatively low but I foundhttps://www.cleanenergywire.org/factsheets/what-german-households-pay-powerwhich shows it is the most expensive in Europe due to high taxes. Well, I guess Germans are rich and can afford such high prices.In Spain we have high prices and low incomes so we have to save. It would be interesting to compare energy consumption in different countries.I find it interesting to discuss the different electrical systems, regulations and customs in different countries and I might open a thread in Chat on this topic if I feel I have the energy to write about it.

author: Zero999
author_rank: Super Contributor
timestamp: January 17, 2019, 12:44:55 pm
content: In the UK power is mostly distributed as three phase, but it gets split up into single phases, when sent to houses and small shops. Pole mounted transformers are rare and are only found in remote rural locations, such as farms, which have a three phase power supply.