12 V DC to a 220V AC Inverter AMplfier Design

[faizanbrohi]

THere is an idea in my mind which i want to ask if it is applicable or not. THe Idea is to create a SInewave Oscillator , amplify the sine wave signal and that it reaches a 220V P-P ,

Sine wave oscillator -->  Class A Amplfier --> 220V Sine wave AC Signal

The only thing i don't know is how the amp need to be designed or even if this idea is correct

 

[audioguru2]

A 220VAC sinewave is 622Vp-p.
A Class-A amplifier uses its full power whether it is fully loaded or not, so becomes extremely hot and wastes as much power as it delivers at full load. It is a total waste of power at low loads.

Think about using a Class-D switching amplifier that is very efficient (doesn't waste much power because it doesn't get very hot).
The inverter has a very high output voltage so maybe it would be less expensive to use a high current medium voltage Class-D audio amplifier driving a stepup transformer.

 

[faizanbrohi]

i have another idea  why use a power amplifier  ;D

Generate a Sine wave oscillator and then use a transformer simply to step up the Signal of 10V to 220V , i mean as simple as it gets . Beacuse since the 10V is an AC SIgnal. But as simple as it is , the Current Rating of the oscillator should be very high . so we can make a sinewave oscillator using power transistors with high current ratings , or power op amps .

plz reply if it is correct  ???

 

[audioguru2]

Your idea of using a linear sine-wave generator wastes a lot of power as heat. Even if the high current output of the generator operated in Class-B to save power when the load was low, it would heat about the same power as the load at full output. Half the power from the battery would be wasted.

If you use a 12V battery then the output from the generator would be a sine-wave of only about 3.5V RMS. If it was designed like an audio power amplifier then for 1000W output the circuit would heat with 1000W, the battery current would be 184A and the load on the circuit will have an impedance of only 0.012 ohms.

If you use a Class-D switching output then only 5% to 20% of the battery's power would be wasted as heat.

 

[Muhammad Abu Bakar]

Then what about class-C amplifier?

Why it isn't used at power frequencies. After all it has good efficiency!

 

[audioguru2]

A Class-C amplifying transistor conducts only part of the time so has very high distortion. Radio circuits use them because they can tune the LC load to substatially reduce the distortion. 50Hz or 60Hz is such a low frequency that an inductor and capacitor to tune to the low frequency with high power is impractical.

 

[Muhammad Abu Bakar]

Soes impractical means immpossible?

One more question.

In an LC tank often a transfo is used as inductor(antenna on other side). Does this transfo has some rigid inductance or it depends upon the load impedence?

 

[audioguru2]

Look in Google for "ferro-resonant transformer". It has a third winding that is tuned by a capacitor to be a tank circuit. It is designed so that its core saturates which makes voltage regulation but a square-wave, then the tuned winding converts the square-wave to a sine-wave.

 

[faizanbrohi]

I think you don't get the point i am saying if use a ordinary sine wave oscillator and then attach it to a Step up trasformer , that is it

 

[faizanbrohi]

ok i get it , it heats more at the oscillator stage , but it can be a way to tackle it good ....

 

[audioguru2]

ok i get it , it heats more at the oscillator stage , but it can be a way to tackle it good ....

It is not good to make an inverter that wastes as much power as the load uses.
An inverter should be efficient, and use a switching amplifier instead of a linear amplifier.

 

[faizanbrohi]

So are there any ideas for a switching amplifer and how is it to be interfaced with my oscillator idea... and the transformer one..

 

[audioguru2]

So are there any ideas for a switching amplifer and how is it to be interfaced with my oscillator idea... and the transformer one..

Class-D switching amplifiers are complicated. Ones for audio use a fairly low supply voltage. TI has an IC with up to only 240W output.
A sine-wave oscillator would drive a class-D amplifier which would drive a stepup transformer.

 

[faizanbrohi]

A switching Class D AMplfier is hard to make , is it no other idea to use any other type of amplfier.

 

[audioguru2]

Maybe your load doesn't need a sine-wave and will work from a simple square-wave inverter.
A "modified sine-wave" inverter has a square-wave with a step in it and isn't too hard to make.

 

[kachew]

Dear Audioguru,
Do you have the modified sinewave inverter circuit ??? can share it out for our knowledge?? ;D ;D just asking....

 

[audioguru2]

Do you have the modified sinewave inverter circuit ???

Somebody posted a circuit but it is on the broken hard drive of my old computer.

 

[kachew]

dear audioguru,

can u describe how its look like?? hehe ;D  ;D maybe i have it... ;D ;D

 

[kachew]

;D ;D