Inverter Circuit 12V DC to 230VAC Sine Wave

[audioguru2]

Chk it out a nice peace of work

could any one see a way to devolop it further

It has a square-wave output so its peak voltage is too low to operate many electronic devices whose rectifier charges its main filter capacitor to the peak voltage of a sine-wave from the mains.
It is smart enough to use Mosfets for reduced heating instead of the hot ordinary transistors in our 500W square-wave inverter project.
Its circuit would be much more complicated if it was re-designed to produce a modified-sine-wave or true sine-wave output.

 

[faizanbrohi]

Will a Ferrroresonant Transformer Produce a Sinewave from the Square wave input and one more thing , as shown in figure is it possible to use a simple transformer and then add a capictor at one end with some rating

View attachment 39375

 

[audioguru2]

I don't know how good is the sine-wave from a ferroresonant transformer that operates saturated and has a square-wave input. Since its primary is saturated then I don't know how high is its input current. A ferroresonant transformer is rare so probably is very expensive.

 

[faizanbrohi]

I think just using a simple LC Circuit at the output will be goood
.  but the problem will come as the RC circuit produces a sawtooth if a square wave is input . i don't know what happens to a LC Circuit , it would produce a sine wave , but will not be linear

 

[audioguru2]

If you tune a winding on a transformer with a capacitor and drive it with a high impedance so the Q remains high, then the output would be a perfect sine-wave without a load and the voltage would be infinite, then turn into a square-wave at the normal voltage when a load is added.

 

[faizanbrohi]

Well amazingly i found a UPS Inverter . and well it is quite complicated , dual layer PCB and all that stuff . i cannot use the parts in it , beacause it is my dad's office UPS and it is dead . so here are some of the things i found .

* 4 mosfets IRF240 , 2 sets in parallel .
* BUZ11 mosfet
* Transformer ( Don't know if it is a ferroresonant Transformer or not )
5 wires coming out of the input side , one is connected to battery directly. 4 wires coming out from the Input side .
* 4 Logic Gates IC , like CD4077 , CD 4093 , TC 4093 and MC14081
* One Quad amp LM339

Now condsidering the following components , i think the Logic gates produce a approximation sine wave and then is filtered into sinewave with a LM339 Quad amp and then Mosfets are used to increase the current , THen THe transformer does the step up .. All in all it is producing a approximation sine wave , i think
what do you think ? comment

 

[audioguru2]

Most people throw away their UPS when its battery dies. Maybe that one just needs a new battery to work again. Look up its model number and manufacturer in Google.
An LM339 is a quad comparator. It cannot be used as an opamp so it cannot filter a signal. Maybe the output is a modified sine-wave that is a square-wave with steps in it.

 

[faizanbrohi]

But this one is battery dead as well as circuit dead , i used it 4 years back to run television , even a computer , it was known here as a 486 computer UPS
You are right i think it is a Modified Sine wave . we can make a modified sine wave and then step up without heating and also can use mosfets. for low heat dissipation

 

[faizanbrohi]

IF we make a sine wave inverter with making sine wave instead of square wave and and use mosfets in our design 4 parrallel mosfets oen side and 4 parallel mosfets other side, IT willl minimize heat dissipation and we will have a sine wave inverter.
BUt making a modified sinewave wave , a digital which has steps in it , would be easier , but will it run a TV or Computer . The UPS I had , if it produces a stepped sine wave , then , i used it to run a computer , full with CRT monitor also and a TV also ran fine .

 

[audioguru2]

A sine-wave inverter wastes a lot of power in its output devices. Mosfets or transistors will dissipate the same and heat the same.
If you make the peak voltage from a modified sine-wave inverter about as high as the peak voltage of a sine-wave then it should be able to power anything.

 

[faizanbrohi]

Can you suggest a circuit for the Modified SIne wave inverter

 

[audioguru2]

Can you suggest a circuit for the Modified SIne wave inverter

Sombody posted one awhile ago but I didn't keep it. Google sells many inverters but no circuit is shown.
You could probably use a CD4047 oscillator/divider and some gates.

 

[ishaqfunsho]

hum ......i quite follow the discussants with a keen imterest, however, the discussion did not tell us whether the cct worked or not--pls i will like to know..I equally wish to know what has to be done to increase the power to atleast to 1000w.

 

[grateful]

;DHi,audioguru:

what i found is the ferroresonant transformer provides squarewave output but just require less filtering......

if i use PWM method  to convert a low VDC to high VDC through a ferro transformer.

Then using H-bridge (which is switch by PWM) to chop the high VDC to obtain 240VAC that have multisteps PWM which look like sinewave waveform.... will this work? ???

 

[audioguru2]

if i use PWM method

 

[kachew]

hi grateful,
can i know where u put the H-BRIDGE in the circuit? is it at the output of the inverter?
thanks

 

[grateful]

I c ...thanks....but is there any low cost but effective ways to convert a 12VDC to 220VDC?

Hi,kachew....at the moment i still on thinking...so,i still not certain with this design yet... :-*

 

[audioguru2]

I c ...thanks....but is there any low cost but effective ways to convert a 12VDC to 220VDC?

You could make a "boost converter" with an IC. It makes a high frequency, high current square-wave with Mosfets driving a small high frequency stepup transformer. Then rectify and filter it into 220VDC.

 

[grateful]

Hi there, does anyone know how to convert the different width pulses(vertical) of a PWM signal to different height pulses(horizontal) accordingly....any comparator I C can do this ???

Thanks. ;D

 

[audioguru2]

The output of a comparator IC can't make variable height (voltage) pulses because its output is either high or low.
The PWM pulses are converted to a smooth sine-wave with a lowpass filter.