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hi power dc-ac inverter designe

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richmon74

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www.nalanda.nitc.ac.in/resources/ee/ebooks/vt.pdf

I want to make a dc inverter that will be able to carry 10 computer with 15" regular CRT monitors for each.
* what power output should i target?
* what is the best dc Voltage i should use? i have an option of 24Vdc and 48Vdc
* What kind of oscillator will be more adviceable; pwm, winebridge, cristal sine wave, square wave, pulse etc?
* has anyone done a project at this level could he share his experiences with me?
* which EDA programm is best for simulating this kind of ccts? i've tried simpler ones with protel and it's actually a mess
* or does anyone have an already design circuit for this spec. and is willing to share?
* any website for in formation/circuits on this level of project?
* between FET abd BJTs which one is preferable and why?
* what kind of transformer design is best for this? (details if any)
* what really determine the output power; xformer or power transistor
* what is the effect of frequency on the output power

I've been trying my hands on inverter projects for sometimes now and it hasn't been really eassy. any help will be appriciated and i hope it will be usefull to others in this forum also
 

toxadi

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high frequency inverter schematic

Do NOT use square wave. It may be a lot easier to build but it really stresses switcihng power supplies and transformers. Old tech UPSs used it but not any more.
 

Thiago

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welding inverters practical schematic

I need also ome projects about power inverter, 300 V to 10 V for weld aplications, and i want informations about how to projet a high-frequency transformer and full-bridge....so if anyone have something, please send me :)))) thank all :)))
 

ted

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dc to ac inverter schematic 1000w

I try to address some of your isues-- even if my experience is of systems of very much lower effect levels than you seem to need.

First of all, be aware that Watts are not VotAmps. You have to consider the VAs when calculating the system. Of course, modern equipment do not have as bad cos-phi figure as it was only a few years ago, thanks to approval requirements.

You should not forget the old good Google search, with relevant keywords. There are much material out in the net!

1) * what power output should i target?
You have to research the VA figures of those devices. And also consider the startup situation. Best way is to use both the name plate figures and make some measurments as well.

2) * what is the best dc Voltage i should use? i have an option of 24Vdc and 48Vdc
The desicion here is mainly depending on a few factors:
- Smaller voltage means higher currents, and potentially more ohmic losses.
- Higher voltage needs high voltage transistors and other components.
I would start investigating 48 V and moderate frequency (25-50 kHz or thereabout, maybe somewhat more if the components perform well on frequencies) as a starting point.

3) * What kind of oscillator will be more adviceable; pwm, winebridge, cristal sine wave, square wave, pulse etc?
In my opinion. selection of oscillator is not the most critical task in the beginning. Your need will be affected on the selected converter topography, and you should start there.

4) * has anyone done a project at this level could he share his experiences with me?
Sorry, not me. Have worked on much smaller constructions....

5) * which EDA programm is best for simulating this kind of ccts? i've tried simpler ones with P*otel and it's actually a mess
I think there is no general purpose simulator for designs of this kind, partially because the component models are insufficient, partially because the discontinuous environment (switching!), and dependency on usually very secondary parameters.

6) * or does anyone have an already design circuit for this spec. and is willing to share?
* any website for in formation/circuits on this level of project?
-Look around in the net, too!

7) * between FET abd BJTs which one is preferable and why?
- More research at Internet and at component producer's web sites might help....

8 ) * what kind of transformer design is best for this? (details if any)
- The transformer will be a very "hand-made" device. I would consider large E cores as the first approach, they are available with plenty sizes.

9) * what really determine the output power; xformer or power transistor
- Both! The design is an entity, all parts count.

10) * what is the effect of frequency on the output power
Frequency <20 kHz leads easily to audible noise and should be avoided.
Magnetics get smaller with higher frequency, but demands for transistors increase and switching losses are more consern on higher frequencies.
My gut feeling is 25-50 kHz as the starting point. Be aware that any ferrite core material has its optimum frequency range. Also on higher frequencies the wire inductance and grounding gets (even) more troublesome. On the other hand, "everything", specially the transformer, gets smaller on higher frequencies. Be also aware the ripple current limits of capacitors, that can be an issue even on smaller effects than your design requires!

Good luck!
ted
 
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richmon74

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inverter dc12 to 220 ac 50 hz use igbt

thanks so much Ted
i really thought that bye now i would have gotten enough response in order to know what to do but it seams people don't really know this topic here
 

Mr.Cool

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output transformer dc/ac power inverter analysis

hi, i know this topic well. i am making an inverter for 120V AC (rms). you must choose a topology first. i would suggest a Full H-Bridge because of its current carrying capability.

then you must create PWM switching for the elements. the switching elements should be MOSFETS at power levels of 500W or less. BJTs are for less than 1A projects. IGBTs are quickly becoming industry standard, but generally are reserved for high power application. you can get free samples of these at w*w.fairchildsemi.com

to create the PWM you need to compare a sine wave with a triangle. this is the most common method. i would strongly recommend a trip to the library to descover about bi-polar and unipolar switching schemes. you must understand things like amplitude ratio and frequency ratio, over modulation, harmonics etc.

a transformer is not really necessary if you design your inverter properly. it is used only for isolation or sometimes also as a step up/down.

note that you must filter the output of your inverter. if you do not, you will see a bunch of square waves and not a sine wave! you need a large choke inductor (a self wound ferrite core will saturate instantly at this high of current, so don't try that). also a capacitor might help, in parallel.

good luck.

Mr.Cool
 

Mr.Cool

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schematic on how to remove thd+noise in inverters

my advice above is ment for high power applications. the desine is basically the same though for any level. you just change the switching elements to suit and make minor tweaks elsewhere.

my experience is with 1000W +

i make 60Hz AC output, synchronized to the Grid.

for simulation, you can try PSIM. i think v4.1 is available for d/l. the web site says v5.0 is the latest.

Mr.Cool
 

j_o_n_i

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inverter designe

Hi richmon,

I've been working with inverters for the past two years now, installing and repairing them i have been trying to build one myself these last months but it's no easy job.

Before starting the design you should have sth things clear

The power!
From my experience you need more than 2500VA and possibly a 3kVA inverter should suit your needs, from the practical point of view you have to make your calculations a bit better, there are 10 PC ok, but you need a correct illumiantion, you may also need a printer or sth else... I have installed 3000VA inverters with 8 computers and it hasn't had problems.

Backup time!
Another important parameter you should decide is the backup time of your system. Thats a very influent factor in the design of the inverter but more importantly in the chargher
( I don't know if you're planning to build the charger into the inverter or buy one, my inverters have a built in charger and its very efficient because it uses the same transformer that is used in the inverter mode)
You have to make a good caculation if there is a good enough ratio of time when the mains(energy from the local power line) is present and when is actually missing in order to ensure enough time during the rest of the daynight for the batteries to recharge (you will have to use more than 200Ah batteries and they need a lot of time to recharge)

I don't have any more time right now but i'll write sth else later
regards
joni
 

richmon74

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3kva inverter circuit diagram

Mr.Cool said:
note that you must filter the output of your inverter. if you do not, you will see a bunch of square waves and not a sine wave! you need a large choke inductor (a self wound ferrite core will saturate instantly at this high of current, so don't try that). also a capacitor might help, in parallel.

good luck.

Mr.Cool
this is one unit which always gives me a lot off headage. can u plz throw more light on this. a basic schematic will help a lot.

can u plz send ur schematic (1000w) to my e-mail with some basic describtions - it maight help so well
 

richmon74

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inverter+20khz

thanks joni for reminding me of the charger
yea i intend to build the charger inside and i'll need a high current charger since power outages here is very frequent

so any help on the charger will be well apprieciated. i'm not familiar with using one transformer for inverter and charger at the same time, a basic schematic with the explanation of the most important point to consider will be ok

richmon74@yahoo.com
 

j_o_n_i

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details on the driver stage of a 3kva inverter

I'm continuing to give my answers to your first post:

24 to 48 V
hmm i'd prefer 48 volt in your case, because of the high power so you don't have to use very thick cables both inside and outside the inverter
for 3000VA you can have more than 65 A for 48V double that for 24 V
the most important point related with this is the most expensive part of the inverter: the Transformer. I think forst you should find or just choose a transformer and then you build all your inverter around it. With regards to the charge there's quite a simple solution if you have an extra output in the transformer it uses a couplr of thyristors but you can use a triac too. I'm going to send sth one of these days its that i'm in the middle of an exam session :)

I've worked with both Square wave and PWM but i'm not familiar with the others. Definitely PWM is much better than square wave main reason in pwm you can have a much stable output voltage controlled by an IC while in SquareWave the output voltage is directly dependent to the battery voltage. You can do some kind of stabilising using relays at the output but i don't like that at all. SquareWave may be a bit easier to design bit it isn't worth it.

Ah Mr.Cool, My project lacks an Output filter too any link on that would be helpful thnx

joni

PS. I never managed to simulate my inverter on an EDA tool. I use SG3524 and have found only one model but it doesnt seem to work. I don't think the prodlem it's only there I think that when the schematic has too many components no eda tool can simulate it correctly (until now ) I managed to simulate one part of it with pretty good results (1/4). If I remember well you were searching the model for this IC too some months ago.
 

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igbt+dc-ac converter schematic

I just wonder in such application whether the Sinusoidal output is really needed.

Normally the computer and monitor have their own SMPS bulit-in, and those power supply will rectify the input AC to DC. If just diode rectifier is used and no PFC circuit presents there, then DC or square wave feed-in should be fine.
 

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high frequency inveter project example free

Thiago said:
I need also ome projects about power inverter, 300 V to 10 V for weld aplications, and i want informations about how to projet a high-frequency transformer and full-bridge....so if anyone have something, please send me :)))) thank all :)))
For the transformer core, ferrite or metalglass is your choice. The latter is much more expensive.

Another thing you need to take care is the output stage, generally you will use a diode rectifier after high frequency link. However, the reverse recovery of that diode will be a big headache, it may cause the diode over-temperature or eventually burned.
 

richmon74

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ee/ebooks/vt.pdf

i'm still on this project and i still exp[ect response
thanks
 

lebrit

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synchronized inverters

You can use two stages conversion:
1) DC-DC from 48V to +/- 180V using an H-bridge and a HF (100-200kHz) transformer.
2) DC-AC converter using Neutral Point Clamping switch topology.
 

richmon74

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48v battery inverter

lebrit said:
You can use two stages conversion:
1) DC-DC from 48V to +/- 180V using an H-bridge and a HF (100-200kHz) transformer.
2) DC-AC converter using Neutral Point Clamping switch topology.
Plz give me more details of these...links will be appreciated
 
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upol

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how to build a 3kva grid tie inverter.

Did anyone succeed with the project?
I am wating for a UPS circuit diagram
Hope someone will work this out.
 
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richmon74

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high frequency inveter project free

upol said:
Did anyone succeed with the project?
I am wating for a UPS circuit diagram
Hope someone will work this out.
what kind of ups do u want? i have a couple of circuits (working) in my drawer
 

upol

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charger +designe+circuit

I just need a simple circuit which parts are common and easy to build and not a very large power is required. A 5 min backup will do just fine for me
thanks
 

richmon74

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1000watts inverter schematics free download

upol said:
I just need a simple circuit which parts are common and easy to build and not a very large power is required. A 5 min backup will do just fine for me
thanks
for such simple circuits u can do a search on google and your will get a handfull of them

I'll still send some circuits to u later
 

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