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500W sinewave inverter, 3 questions

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jolly_girl

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hi all... my project is to design a 500W sine wave inverter. :idea: with battery backup.

so i hv to design a battery charging circuit and then SPWM inverter.

for 500W, m using a 120Ah lead acid battery.
so i'll need a constant current of about 12A at about 14V to charge d battery. This is where i need your help, how can i design a constant current source at this voltage level.

2nd phase is : Inverter.
my partner is working on that. this is wat she suggested to me --->

1.we'll generate sine wave (50Hz) and triangular wave (10kHz) using XR2206
2. compare them with LM311 to generate our spwm signals
3. use an optocoupler to provide these pulses to our mosfets


So.. wat do u think... is this scheme gonna work or are there any better ways to do it :idea:

m waiting for ur suggestions..

thanx :D
 

Re: 500W sinewave inverter

for charging purpose.. u can use this

**broken link removed**

this is for 13.8V, but that can be adjusted using the regulator.. i hope this will serve your purpose. or u can use LM723, it also provides current limiting as well as current boosting..

regards
sameer
 

    J

    jolly_girl

    Points: 2
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Re: 500W sinewave inverter

thanx sameer,

i think this will serve my purpose... n wat abt trickle charging.. i will need about 300ma current for that at about same voltage level. well i think this circuit will also serve my trickle charging problem... battery will draw less current when fully charged n this circuit will easily provide it... isnt it ??.. or is there anything else u want to add


thanx
 

500W sinewave inverter

First of all, you are not going to build a pure sine wave inverter as they are extremely complicated.

Also it seems like women in india are smarter in technical fields then here hmmmm.
 

Re: 500W sinewave inverter

yaa thats rite smeezekitty... m not aiming for a pure sine wave but atleast by using spwm (n a few filters) i can have something like sinewave.. isnt it !!

1 more thing i was curious abt was that my inverter output will be some pulses(with variable width) at dc level of 12V or less, so i'll have to use a step-up transformer n this is where i was wondering if this xformer going to work fine... i mean problems regarding saturation n heating due to harmonics will be there.. wat can be done in this matter ??!!

i really need ur help tech-heads.. do make some suggestions.


thanx



n yes.. women in India are smart in technical field too :)
 
Re: 500W sinewave inverter

enter
Well if you mean use output filtering to turn square wave to sinewave, you will loose alot of power doing it.
leave
ret
 

500W sinewave inverter

The 10kHz waveform is modulated at 50Hz by PWM.
So it is not a square-wave. It is easy to smooth it into a pure sine-wave with a lowpass LC filter.

Most inverters use a high frequency power oscillator and a small ferrite transformer then rectify and filter it to make 330VDC. They use high voltage Mosfets and switch them with the PWM.
 
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    jolly_girl

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    K

    kif123

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Re: 500W sinewave inverter

" Most inverters use a high frequency power oscillator and a small ferrite transformer then rectify and filter it to make 330VDC. They use high voltage Mosfets and switch them with the PWM "


thanx audioguru , but i think this scheme gonna b a bit difficult for me. can u suggest me something to generate spwm pulses using some ICs or function generators..

thanx..
 

500W sinewave inverter

Most pure sine-wave inverters use a TL494 PWM controller IC. It switches high voltage Mosfets on and off at a high frequency from a +330VDC supply made with a power high frequency oscillator which is stepped up with a small ferrite transformer, a rectifier bridge and a filter capacitor. Then the high voltage high frequency PWM signal is smoothed into a pure sine-wave with a small ferrite LC filter.
It is easy for it to have its output voltage regulated.

If it is too difficult for you then design or copy a square-wave inverter that was used 40 years ago.
Its output voltage is not regulated. Many modern electronic products will not work when powered from it.
 

500W sinewave inverter

oki then... if this is wat it takes then i'll do it... can u pls attach some schematic for this.. m also searching but since u know it well u can decide which one is better..

n just one more thing i wanna know is that wats wrong with the method i mentioned in my first post(using xr2206, etc)

thanx.
 

Re: 500W sinewave inverter

jolly_girl said:
i wanna know is that wats wrong with the method i mentioned in my first post(using xr2206, etc)?
Click to expand...
Wanna?? Wats??

The TL494 has a triangle-wave generator and a comparator. It also has circuitry to provide some dead-time preventing both output transistors from being turned on at the same time. It also has a 5V voltage regulator. It also has error amplifiers and feedback that can regulate the output voltage.

So why not use it instead?
 

500W sinewave inverter

sry for the wanna..wats.. thing.

ya m studying TL494 n it seems to be a better option..thanx.. but m still lagging in the circuit diagram for the operations.. can u help me with that ..pls.

thanx
 

500W sinewave inverter

My electricity is very reliable and I don't go into the bushes for hunting so I have never used an inverter.

Also I have never seen a TL494 IC.

Sorry, I am not interested in making an inverter when inexpensive Chinese ones are available.
 
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    ali_01

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Rofl Rofl at the last reply ... She is typical indo-asian girl knowing nothing and asking for a cooked thing :d
 

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