I'm looking for a DIY design for a 20kw pure sine inverter. There are many resources for building 1-3kw versions, but none for an inverter with a 20kw output. If someone has a design they could share or explain to me exactly how to modify one of the smaller inverters to handle the extra power capacity, that would be great. The input is coming from a 220VDC/50amp generator and the output from the inverter should be 220VAC@50hz with about 20kw load capacity, enough to power a household.

I have not worked with electronics for quite some time (decades) and this project is looking much bigger than I had anticipated; I wonder if it makes more sense to buy one, but my friend is insistent that we build it ourselves. Thank you for any help you can provide!

 

Actually, going a step further, assuming people have already designed this circuit, would anyone have a printable PCB layout and parts list?

 

20KW is a very large inverter and far from a trivial design task
It is something that should not be attempted by someone not experienced in high power electronic design.
I wish you luck but you are also unlikely to find a posted circuit for that.

Disagreeing with you friend, I think you would be better off to buy one ready built.

 

How do you expect to get 20kW from a 11kW generator?

 

Here's how You do it ..........

Replace the "" 220VDC/50amp generator ""
with a 220VAC/50-Amp Generator.

Problem solved,
and,
it will cost-less, be more efficient, and last for at least ~50-years.

Then You can re-sell the DC-Generator to defray some of the costs.
.
.
.

 

I'm looking for a DIY design for a 20kw pure sine inverter. There are many resources for building 1-3kw versions, but none for an inverter with a 20kw output. If someone has a design they could share or explain to me exactly how to modify one of the smaller inverters to handle the extra power capacity, that would be great. The input is coming from a 220VDC/50amp generator and the output from the inverter should be 220VAC@50hz with about 20kw load capacity, enough to power a household.

I have not worked with electronics for quite some time (decades) and this project is looking much bigger than I had anticipated; I wonder if it makes more sense to buy one, but my friend is insistent that we build it ourselves. Thank you for any help you can provide!

220VDC at 50 Amps equals to 11kW power. Your inverter will not ouput more power than you input.

 

...this project is looking much bigger than I had anticipated....

It's even bigger than it looks. It makes a lot more sense to buy one, but if you proceed to design one the maths say you will get 220V * 50A = 11kW from your generator and less from your inverter, so your requirements need rethinking for a start.

 

I agree with @LowQCab , remove the dynamo from the engine and replace it with an alternator. A brushed dynamo would indicate that it is rather old.

 

Only a small portion of the circuit could exist on a circuit board.
In addition, the previous comments are certainly correct, in that a 20 KW inverter will not simply be a scaled up 2 KW inverter.
Besides that, a "pure sine wave" circuit will either require a resonant transformer or a linear switching arrangement, which will not be efficient. This means that at best the output with 1100 watts DC input would be less than 5500 watts, and the heat losses would also be 5500 watts.
So it will be far more effective to get an AC generator to provide the power directly.
The 1100 watt DC generator can be used to power the existing incandescent lighting system. If connections are separated from all else.

What area of Electrical Engineering did the TS focus on???

 

"Pure sine wave" is achieved by PWM, as in a Class-D audio amplifier, so the efficiency is >95%

 

at 50 Hz and 20 KW, the filter would be a monster. But certainly the resonant 20KW transformer would be a good filter. Of course providing adequate regulation would be a challenge.

 

enough to power a household.

While a common US residential power delivery may be 240 VAC 200 amp service I doubt anyone will ever run close to that capacity. Next as mentioned if you start with 220 VDC 50 amp you are starting with 220 * 50 = 11 KW. You will never get out more than you put in. Even in a perfect world you would need to start with over 220 volts 92 amps and that does not begin to take into consideration efficiency. There is no 100% efficient. Your least expensive and most reliable source of 220 VAC @ 20 KW would likely be a generator. Building a 20 KW 220 VAC inverter is a seriously large challenge. Commercial inverters for solar system that size will normally be 3 phase 480 volt with a price tag of about $4,200.00 USD. Even these units require about 26 KW in to get 20 KW out so back to efficiency.

Ron

 

at 50 Hz and 20 KW, the filter would be a monster. But certainly the resonant 20KW transformer would be a good filter. Of course providing adequate regulation would be a challenge.

It's generally done with a split-bobbin transformer using the leakage inductance as the filter. It can also be done with toroids where the low voltage winding only covers half the toroid.

 

It'll be cheaper to buy one used or even new. Chinese factories buy parts for a fraction of what they'll cost you, and do whatever QA is necessary to ensure they don't get ripped off.

 

I just wanted to thank everyone who responded. I honestly didnt think anyone would because most sites I find myself on for any reason are basically defunct. Glad to know the engineers are still passionate; I appreciate it. And yes, I dumbed down my question a bit because, like I said, I did not expect any response, let alone so many! We're moving forward apparently, just for the fun of it! Cheers & 73's

 

It's generally done with a split-bobbin transformer using the leakage inductance as the filter. It can also be done with toroids where the low voltage winding only covers half the toroid.

A FIVE KW 60H control transformer is quite heavy, and a 20 KW transformer will probably weigh about four times as much, close to 100 pounds. Are transformers that large still wound on bobbins??

 

For a home to draw 20kW it must have electric heating and air conditioning both running at the same time.
The home has no insulation?
Is the outdoors swimming pool heated with electricity all winter? The pool at a neighbor has steam all winter but it is heated with natural gas.

 

There are people with homes far larger than any folks who visit this site.
There are also people who have no clues about how much power a home uses.
There are some folks who are not quite what they claim to be.
And there are those folks who are a lot richer than me. Think about Jeff Bezos, the guy who just lost 54 BILLION DOLLARS a few days ago, and halted construction work on his new house.
My guess is that the new house would have 20 KW electrical service.

 

Um, 100A service is quite common, I have it, and that is 24KW..

 

Some people still heat their homes with oil or electricity (lots of money).