Author Topic: Single phase to three phase sinewave converter  (Read 10602 times)

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Offline sanwal209Topic starter

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Single phase to three phase sinewave converter
« on: January 12, 2019, 10:40:53 pm »
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 Regards
Sanwal Saleem
 

Offline ArthurDent

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Re: Single phase to three phase sinewave converter
« Reply #1 on: January 12, 2019, 11:30:41 pm »
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/
 

Offline NiHaoMike

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Re: Single phase to three phase sinewave converter
« Reply #2 on: January 12, 2019, 11:34:47 pm »
Look up "VFD".
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Offline Bratster

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Re: Single phase to three phase sinewave converter
« Reply #3 on: January 13, 2019, 12:04:55 am »
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 Regards
Sanwal Saleem
What 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.

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Offline soldar

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Offline TimFox

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Re: Single phase to three phase sinewave converter
« Reply #5 on: January 13, 2019, 02:13:21 am »
Google “Scott-T Transformer”.
 

Offline sanwal209Topic starter

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Re: Single phase to three phase sinewave converter
« Reply #6 on: January 13, 2019, 02:50:45 am »
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.



 

Offline CatalinaWOW

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Re: Single phase to three phase sinewave converter
« Reply #7 on: January 13, 2019, 03:02:39 am »
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?

 

Offline beanflying

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Re: Single phase to three phase sinewave converter
« Reply #8 on: January 13, 2019, 03:27:25 am »
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.
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Offline sanwal209Topic starter

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Re: Single phase to three phase sinewave converter
« Reply #9 on: January 13, 2019, 03:38:36 am »
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
 

Offline CatalinaWOW

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Re: Single phase to three phase sinewave converter
« Reply #10 on: January 13, 2019, 06:17:50 am »
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
 

Offline soldar

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Re: Single phase to three phase sinewave converter
« Reply #11 on: January 13, 2019, 09:12:39 am »
Google “Scott-T Transformer”.
I googled and found
Quote
https://en.wikipedia.org/wiki/Scott-T_transformer

A Scott-T transformer (also called a Scott connection) is a type of circuit used to produce two-phase electric power ( 2 φ, 90 degree phase rotation) from a three-phase ( 3 φ, 120 degree phase rotation) source, or vice versa. The Scott connection evenly distributes a balanced load between the phases of the source. The Scott three-phase transformer was invented by a Westinghouse engineer Charles F. Scott in the late 1890s to bypass Thomas Edison's more expensive rotary converter and thereby permit two-phase generator plants to drive three-phase motors.

At the time of the invention, two-phase motor loads also existed and the Scott connection allowed connecting them to newer three-phase supplies with the currents equal on the three phases.
Since 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.
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Offline soldar

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Re: Single phase to three phase sinewave converter
« Reply #12 on: January 13, 2019, 11:04:13 am »
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.
« Last Edit: January 13, 2019, 12:34:48 pm by soldar »
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Offline capt bullshot

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Re: Single phase to three phase sinewave converter
« Reply #13 on: January 13, 2019, 11:25:23 am »
http://wunderkis.de/pwramp3/index.html
scroll down to "Input related stuff" - all analog.
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Offline station240

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Re: Single phase to three phase sinewave converter
« Reply #14 on: January 13, 2019, 01:33:51 pm »
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
 

Offline duak

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Re: Single phase to three phase sinewave converter
« Reply #15 on: January 13, 2019, 07:35:25 pm »
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-shifter   To 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,
 

Offline soldar

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Re: Single phase to three phase sinewave converter
« Reply #16 on: January 13, 2019, 07:54:25 pm »
Generating 3 phase from 2 phase quadrature is quite easy. 
Well, 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).
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Online Zero999

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Re: Single phase to three phase sinewave converter
« Reply #17 on: January 13, 2019, 08:02:29 pm »
Yes, I think a couple of people here have misread the original post. Here it is again, with the relevant parts highlighted.
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 Regards
Sanwal Saleem

That'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.
 

Offline Yansi

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Re: Single phase to three phase sinewave converter
« Reply #18 on: January 13, 2019, 08:07:23 pm »
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 as https://www.st.com/resource/en/datasheet/stgipn3h60.pdf controlled 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?
 

Offline duak

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Re: Single phase to three phase sinewave converter
« Reply #19 on: January 13, 2019, 09:14:33 pm »
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,
 

Offline Yansi

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Re: Single phase to three phase sinewave converter
« Reply #20 on: January 13, 2019, 09:25:33 pm »
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 find MC3PHAC integrated 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).
 

Offline CatalinaWOW

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Re: Single phase to three phase sinewave converter
« Reply #21 on: January 13, 2019, 11:41:59 pm »
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 find MC3PHAC integrated 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).

This 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.
 

Offline Yansi

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Re: Single phase to three phase sinewave converter
« Reply #22 on: January 13, 2019, 11:44:20 pm »
I have asked few times here, what the real purpose and requirements are. Still waiting for the response.  :-+
 
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Offline T3sl4co1l

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Re: Single phase to three phase sinewave converter
« Reply #23 on: January 13, 2019, 11:54:53 pm »
Google “Scott-T Transformer”.

Not 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.

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Offline Yansi

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Re: Single phase to three phase sinewave converter
« Reply #24 on: January 14, 2019, 12:04:39 am »
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).
 


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