Help needed in push-pull circuit for Inveter.

[koolguy]

You can make a simple square-wave inverter and use a transformer with a single winding without a center-tap if you switch both ends of the winding like this Japanese (100VAC) one (it is simple so it does not have voltage regulation)

Do you think it will work for all AC LOAD??
I have also seen that when i have connected a CFL of 18W on my 12W INVERTER it was blinking very low but a low power filament bulb was glowing(dim) as shown in last pics...

 

[audioguru]

If the output voltage of your inverter is too low then the lights will be dim.
You are using a cheap tiny 12W transformer. Its voltage might drop when loaded with only 10W or less.
I have never seen a incandescent mains bulb less than 25W.

 

[koolguy]

Modern transformers have two low voltage windings so they can be connected in series with or without a center-tap or can be connected in parallel.

Please tell me more about these transformer(voltage rating which one to buy), i will buy this..

 

[audioguru]

Please tell me more about these transformer(voltage rating which one to buy), i will buy this..

Look at www.digikey.com or www.newark.com for powerful dual windings transformers. You can look at manufacturers like Triad or Hammond. I don't know if you can get them in your country.

 

[ChrisP58]

I realize that the circuit shown in post #40 was to show how to drive a transformer that doesn't have a center tap, but there is a big problem with the way that the mosfets are driven.

The gates of the P and N channel mosfets are tied together. This means that there will be a brief time during switching transitions when both mosfets are turned on, causing a direct short between +12V and ground. This condition, known as shoot through, is a big killer of mosfets. Even when they don't die quickly, there will be a lot of power wasted.

**broken link removed**

 

[koolguy]

I want to know that can we use fuzzy logic or neural network for any mean in UPS like for controlling purpose??

 

[audioguru]

I want to know that can we use fuzzy logic or neural network for any mean in UPS like for controlling purpose??

Sorry, I cannot understand your broken English.

 

[koolguy]

never mind, i am asking that how can we use fuzzy controller in UPS.....

 

[audioguru]

never mind, i am asking that how can we use fuzzy controller in UPS.....

You want the output of the inverter in a UPS to be properly controlled.

 

[kubeek]

I want to know that can we use fuzzy logic or neural network for any mean in UPS like for controlling purpose??

Ritesh, I just can´t understsand your logic. You can´t even make an inverter work properly without any control loop, and still you ask how to apply things like fuzzy logic and even neural networks, which most people here either have no clue about or they never heard of it.

You need to learn to do things in small steps.

 

[4pyros]

I want to know that can we use fuzzy logic

yes you can

 

[koolguy]

OK, i have connected that 4001 IC but the voltage level is down ~136Vnow what to do??

 

[audioguru]

You cannot measure the stepped modified sine-wave with an ordinary meter that is calibrated for a real sine-wave.
My meter measures "True RMS" so it might read the voltage accurately.
The transformer must be 9V-0-9V for the average output voltage to be 240VAC and the peak-to-peak voltage to be 340VAC.

Maybe your little transformer is too small and is too cheap.

 

[koolguy]

The transformer must be 9V-0-9V for the average output voltage to be 240VAC and the peak-to-peak voltage to be 340VAC.

But the 12 0 12V should work fine to convert 12V DC to AC??

Maybe your little transformer is too small and is too cheap.

The small transformer is used or testing after that large rating will be used.!!

 

[audioguru]

But the 12 0 12V should work fine to convert 12V DC to AC??

No.
If the transformer is perfect (most have a voltage drop when loaded) then the peak-to-peak output voltage (shown on an oscilloscope, not on a meter) will be 240V. But the new circuit has a modified sine-wave waveform so its average voltage will be only 170V.

 

[koolguy]

No.
If the transformer is perfect (most have a voltage drop when loaded) then the peak-to-peak output voltage (shown on an oscilloscope, not on a meter) will be 240V. But the new circuit has a modified sine-wave waveform so its average voltage will be only 170V.

That mean now i have to change 12 0 12V to 9V transformer??
and I have seen the transformer used in low power UPS (600VA) in that transformer there are many tapping should i buy that??

 

[audioguru]

The modified sine-wave inverter needs a 9V-0-9V transformer. a square-wavew inverter can use a 11V-0-11V or 12V-0-12V transformer.

I don't know if the output of your UPS is a pure sine-wave, a modified sine-wave or a square-wave so I don't know the voltage of the taps on the transformer. Some of the taps might be used to charge the battery.

 

[koolguy]

I don't know if the output of your UPS is a pure sine-wave, a modified sine-wave or a square-wave so I don't know the voltage of the taps on the transformer. Some of the taps might be used to charge the battery.

OK, if it Square wave so what will be tap winding...

 

[audioguru]

On a square-wave, the average voltage is the same as the peak-to-peak voltage. The Mosfets have a small voltage loss.
but a charged 12V lead-acid battery is about 13.2V so the output of the 12V-0-12V transformer should be 240V average or peak-to-peak when loaded. The voltage will be higher when the load current is small.

 

[koolguy]

The modified sine-wave inverter needs a 9V-0-9V transformer.

After using 9 0 9V transformer my multimeter is showing the same reading , why??