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Author Topic: Require Mini Grid Inverter Concept  (Read 4133 times)
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sohel
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« on: May 26, 2013, 03:40:51 15:40 »

Dear all,

I would like to work on solar mini grid inverter . which topology will fulfill my requirement?   

Thanks
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nordiceng
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« Reply #1 on: May 26, 2013, 08:03:23 20:03 »

more details please
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solutions
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« Reply #2 on: May 26, 2013, 09:58:16 21:58 »

The topology that has fuses on the output and a microprocessor controlled zigbee link that sends an email informing your friends/family that you are that pile of carbon that's on the floor (because it sounds like you found a 3 phase boost converter output and think you can make a grid tie out of it).

It's one thing to build an inverter, quite another to build one for fault-tolerant grid tie. You are planning to play with extremely dangerous and unforgiving stuff,I hope you realize - both to yourself and to others (like linemen who THINK they shut the power off). Grid tie is also a nasty environment - it's not just 400V, low impedance, coming AT YOU, but also the huge surges it has from lightning hits, motor starts, etc.

If you do get a design working, you need to have it inspected and certified by the utility before you can connect it to the grid - you could buy dozens of off-the-shelf inverters for what they'll charge you to do it, if they will even give you the time of day. They'll also require you to carry huge liability insurance to pay for their damages from things like your code going off into the weeds or getting hung up, if you use a micro for instance.

Mains stuff, especially that 220/240 or 440V stuff is not something to take lightly, especially if you are attaching to a system capable of delivering thousands of amperes - you really need to know what you are doing. Maybe you do, sohel, but others here likely do not.

Nice knowing you....
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zab
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« Reply #3 on: May 27, 2013, 05:04:44 05:04 »

The best way to start this is to collect all related informations. and a reference designs. I suggest you to download microchip ref. design from here http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en551429
and study it. Get awareness of all dangers and problems and then move forward. MY suggestion is to divide it into individual portions and  build these one by one.
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sohel
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« Reply #4 on: May 27, 2013, 06:45:11 06:45 »

Thanks

I am not talking about grid tied inverter, i am talking about non power area where this inverter will produce power for home appliance. i am calling it mini grid. sorry if i bothering  you.

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PaulC
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information is free and should be shared for free


« Reply #5 on: May 27, 2013, 09:59:09 09:59 »

try this link out and let us know some sort of spec - i.e amps (Load & roughly supply) volts (output) phase (1-3).
and we will go from there..
https://www.google.ie/search?q=36v+to+220v+inverter+circuit+diagram&source=lnms&tbm=isch&sa=X&ei=BiGjUYv8KtCf7AbusIDQDA&sqi=2&ved=0CAcQ_AUoAQ&biw=1052&bih=580
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find it , read it , share it .
sohel
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« Reply #6 on: May 27, 2013, 10:05:16 10:05 »

maybe same topology. i have serviced one of them.

http://www.ipocasa.com/low-frequency-online-ups/3-3-phases-low-frequency-online-ups.html
« Last Edit: May 27, 2013, 10:27:32 10:27 by sohel » Logged
zab
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« Reply #7 on: May 27, 2013, 11:02:15 11:02 »

Thanks

I am not talking about grid tied inverter, i am talking about non power area where this inverter will produce power for home appliance. i am calling it mini grid. sorry if i bothering  you.



you have not mentioned the required power for inverter and its utility. DC to DC converter topology need careful selection. as it has its own implications. Any how, if you need high power then full bridge topology suits you .If less power flyback topology is most favorable for its simplicity of design.you can use 2  flyback circuits switching alternately to get high power as well.If you go for full bridge then ZVT full bridge circuit will give same high efficiency. One more thing need attention is varying solar  irradiance which result in variable power ie. so you need to tackle this problem as well.Either you need battery backup or capacitor bank for stability or you have reduce the load.
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solutions
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« Reply #8 on: May 27, 2013, 11:16:15 11:16 »

OK - so you just want a SINGLE PHASE inverter if it's a household appliance. The sketch you put up in your OP was a three phase output stage, which can be rather expensive compared to a single phase.

I think there were other projects on this site of people doing inverters. Did you look? we also need to know what DC voltage range you're working from and what RMS voltage and frequency you are after.
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sohel
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« Reply #9 on: May 27, 2013, 01:22:51 13:22 »

"I think there were other projects on this site of people doing inverters. Did you look? "

i didnt find.


seeking support from expert.
« Last Edit: May 27, 2013, 01:48:23 13:48 by sohel » Logged
Magnox
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« Reply #10 on: May 27, 2013, 03:24:42 15:24 »

Here's a search tip: Use google and limit the search to sonsivri. I often find it better than a site's own search engine. Type the following into google's search:

inverter site:sonsivri.to
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andig
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« Reply #11 on: May 27, 2013, 07:16:12 19:16 »

Hi,

If I have properly understood then you are looking forward to a GRID 3-Phase alternative supply with a NEUTRAL. (VVF Drives do not use a Neutral). I did one with a PIC18F4331, but  I used a 3 Phase Transformer for the boost. The double conversion topology definitely have the advantage of smaller more efficient design. As suggested by zab ZVT could be the most efficient topology but I couldn't make a successful one, which I suppose is my lack of skill in SMPS design, being an embedded developer in the first place.

Well for a 3-Phase inverter you have a complete lookup table of 360 degrees divisible by 3 then you can have 3 pointers to the table 120 degrees apart. In feedback measure all the 3 outputs and have a compensation algorithm having individual + a proportional of the sum. Why not start by simply generating 3-phase and turning some motors. Phase imbalances and occasional overshoot can be hard to trace if you are not having 4 channel scope with isolated channels (at least I don't have one Sad), but the motor will certainly complain with jerks / sounds.

For the simplest MPPT a perturb and observe is the most done, however with varying loads it can have latency issues in DC-DC and DC-AC control loops resulting in beating. So an incremental conductance seems better.

It has been found on site that irradiance imbalance in panel to panel also causes lower energy extraction.

You mentioned areas where grid is not available, so one question comes to mind, is it an industrial or consumer application. If consumer then why 3 phases are needed ?? My application was running automatic embroidery machines in Bangladesh (as my customer mentioned), however it was battery backed. We used an online like topology. A MPPT DC-DC ->BATT-> 3 Phase Inverter

For the posted topology for the same overall capacity a 3 phase system is only 30% costlier. As you just add Drivers,IGBT,Filter cause your existing MCU/dsPIC may already have 3 or more complementary PWM units.

If Rony from Chittagong is around here he can surely help as he has first hand experience in Solar and Inverter

Regards
Sougata

BTW: Would somebody let me know why my status is "WARNED"
« Last Edit: May 27, 2013, 07:18:43 19:18 by andig » Logged
Magnox
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« Reply #12 on: May 27, 2013, 08:16:45 20:16 »

@andig, go to your profile (click your username) and check the 'warning log' link on the left side to see your warnings.

.....

So, are we talking about single phase or three phase here?

'Household Appliances' implies just single phase to me, I don't know of any household appliance that needs three phases.

I do know that I have seen people using computer UPS units slightly modified to run small appliances from a photovoltaic panel/battery system. Even large units are quite cheap to buy surplus, if they have dead batteries.
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solutions
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« Reply #13 on: May 27, 2013, 08:34:54 20:34 »

"I think there were other projects on this site of people doing inverters. Did you look? "

i didnt find.


seeking support from expert.

A search, using the site search engine for the word inverter yields ELEVEN pages on Sonsivri.

Use your eyeballs to filter, take your pick of what sounds interesting, read the materials, then ask questions in the appropriate thread.

It's still a dangerous project, but not as much as the grid tie. Your biggest headache will likely be the magnetics.
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pickit2
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« Reply #14 on: May 27, 2013, 09:43:14 21:43 »

If Rony from Chittagong is around here he can surely help as he has first hand experience in Solar and Inverter

BTW: Would somebody let me know why my status is "WARNED"
Part of Warning to you
Remember my PM to you :----------- Why No Answer?
I invited a leech and a waste of space

Update; You never did answer my PM so why should I remove a warning that needed you to answer my question?
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Note: I stoped Muteing bad members OK I now put thier account in sleep mode
sohel
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« Reply #15 on: May 28, 2013, 04:34:10 04:34 »

Your biggest headache will likely be the magnetics.

You are right. i am also confused how they did it.

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andig
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« Reply #16 on: May 28, 2013, 05:25:10 05:25 »

Part of Warning to you
Remember my PM to you :----------- Why No Answer?
I invited a leech and a waste of space

Update; You never did answer my PM so why should I remove a warning that needed you to answer my question?

@ pickit2,

I did see your message but can't fully recall the context. Seems I forgot to reply. Accept my apology.

@ sohel can you be specifics on which magnetics you are talking about, the input DC-DC or the Output Filter

Regards
Sougata
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sohel
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« Reply #17 on: May 28, 2013, 06:42:13 06:42 »

"magnetics" love for new topology. Tongue

@ Sougata

I know you can help me because you are expert.

i think Freescale use same topology,

Freescale DSCs in PV Solar Inverter Applications, Application Note AN4615.
« Last Edit: May 29, 2013, 02:37:25 14:37 by sohel » Logged
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