How to design a single phase , 50Hz, 240VAC inverter (grid tied)
How to design a single phase , 50Hz, 240VAC inverter (grid tied)
(OP)
Hi,
Would you agree, that this is a simple job? One simply has to set up sinusoidal PWM into a H bridge, and have output current limitation.
You make sure your DC bus is say , 400V, so that its always above mains peak...then you simply sinusoidally PWM it.....the sinusoidal PWM is made by a ref sine into a comparator with a sawtooth into the comparators other input...and you monitor the current drawn...and adjust the PWM pulse widths until your average output current is correct. Would you agree with this? Its almost an "open loop" operation?
Would you agree, that this is a simple job? One simply has to set up sinusoidal PWM into a H bridge, and have output current limitation.
You make sure your DC bus is say , 400V, so that its always above mains peak...then you simply sinusoidally PWM it.....the sinusoidal PWM is made by a ref sine into a comparator with a sawtooth into the comparators other input...and you monitor the current drawn...and adjust the PWM pulse widths until your average output current is correct. Would you agree with this? Its almost an "open loop" operation?
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
Keith Cress
kcress - http://www.flaminsystems.com
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
But we may be underestimating you. Let us know how it works out.
By the way, shifting the zero point of the PWM signal to control or limit the current may be non-trivial.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
The GTI's only have current and voltage limiting.
The attached LTspice sim shows an open loop GTI doing a pretty good job with no control whatsoever......i admit that a little bit of extra control is needed to get that current sinusoid and in phase with the voltage...but as you can see.....the jobs almost done here, and thats open loop!
This is why i say the GTI is nowhere near as difficult as its made out.
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
..for some reason i cant upload the ltspice sim?
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
It puts a sinusoidal current into the mains. Is mostly analog...would just need some software to generate the sinusoidal reference and do all the protections needed for a GTI.
(LTspice of grid ited inverter attached)
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
What are you planning for a power source feeding your inverter? Where does your isolated 400VDC come from?
-JFPE
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
Why re-invent the wheel?
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
However, we need it to last >10 years, and so we will need to work with the manufacturer over the years to put right any failure points as they (possibly) show up.
The Chinese are great people, they are genuinely decent and superb. China has become "first world" without invading other countries. The Chinese are most honorable.
However, within the next 10 years, the Chinese will (possibly rightly) take over the entire south china sea, and all of its wonderful oil and mineral reserves. The "nine dash line" will belong to China.
When this happens, we believe the West will ban all further trade with China, and so we wont be able to get the support we need for this inverter.
We have to think of such things before we jump in with wallets flashing.
The Chinese are truly decent people though....and we really want to trade with them.
(We are already heavily invested in China, and are really worried that we may get banned from continuing this relationship with China. Especially with all this "climate" talk.
Is this for real?...this villification of oil?.....is it something to do with the fact that the west is running out of oil....therefore they want to villify it?
...its this kind of rhetoric that worries us that soon there may be a ban on trade with china...but we sincerely hope not....we are not pulling our current investments out of china though)
RE: How to design a single phase , 50Hz, 240VAC inverter (grid tied)
That is; Arrange to build your own to a Chinese design under license.
You will be able to replace failed components and with the source code you will be able to tweak performance.
Costs a little more but worth it.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!