Questions about my pwm sine inverter

[gaetan8888]

Hello

I never succed with PIC programing, so I've assembled a schematic of a simple version pwm sine inverter.

I have few SG3524 but no SG3525, and I can't find any SG3525 here around, that why I use a SG3524 in my schematic.

I know that I won't get a very good sine at the transformer output, but I've ad a negative feedback from the transformer output to the SG3524 input to do a better sine.

I can even use one of my big standard EI silicon steel transformer, but it would better to bring down my SG3524 oscillation frequency to 200 hz or 300 hz, because at higher oscillation frequency the Eddy current would be quite high in my output transformer.

At those low oscillation frequency (200 to 300 hz) the LC low pass filter would need a big L coil, but it would be easyer to keep my SG3524 circuit very stable.

Anyones can look at my schematic and tell me if it would work ok ?

Thank you

Bye

Gaetan

 

[MicrosiM]

I wonder about the 110V at transformer output.

Is this supposed to be a SMPS? for?

Why you are trying to drive using sine wave?

 

[gaetan8888]

Hello

IT's a power inverter to convert 12 volt dc to 110 ac, it use pwm to have a sine wave at the output, I would ad a filter at the output.

Most power inverter give a noisy modified square wave 110 ac output, sine wave output are much better.

Thank

Bye

 

[zabi]

Hi,
making sine wave inverter on low frequency will result in lot of power losses in shape of heat dissipation in power mosfet.

 

[gaetan8888]

Hello

I've change the oscillation frequency of the SG3524 in my schematic to 2.36 khz

I can even use one of my big standard EI silicon steel transformer for the output.

Here is the link to my schematic image:

http://data.imagup.com/11/1146939743.gif

Thank you

Bye

Gaetan

 

[MicrosiM]

Sine Wave

Found this file


Hope it help you


Regards

 

[DCPreamp]

I have seen similar applications of DC-AC converters using conventional SMPS's to generate the +185VDC used by the AC driver, but then using actual Class-D audio amplifiers driven by 60Hz, sine-wave oscillators. That way, the entire system is efficient because all power systems are switching and the only analog systems are low-power, signal level oscillator circuits. Then the AC output is very high quality, low distortion sine-waves. It is similar to the SineWave_Generator file MicrosiM posted before, only using commercial Class-D amplifier circuitry like that offered by TriPath or something similar.

There are Class-D, super high powered car audio amplifiers that produce enough voltage and current to operate like a DC-AC converter, but they are far more expensive than commercial sine-wave converters. However, if a damaged unit could be found for a reasonable price, it could be repaired, modified, and used for powering AC devices. That could be a fun project...

Very cool idea! You should pursue it and if you decide to build a converter, post your project here.

 

[joeh_tan]

Great Idea

Hi,
Have you assembled this device and tested? What would be the Max power handling Capacity of this inverter? How can I convert this to a 50Hz, 220V Inverter.

Regards
Joe

 

[szhighstar]

advise to select transformer which core is ferrite.

 

[Tahmid]

For sine wave inverter, you should use sinusoidal pulse width modulation. There are of course other methods that exist. However, I've found it very reliable to use SPWM using microcontrollers. It does become problematic if you're not confident in your programming abilites. However, if you're interested in SPWM, you should take a look at these:
http://tahmidmc.blogspot.com/2011/01/generation-and-implementation-of-sine.html
http://tahmidmc.blogspot.com/2012/10/smart-sine-software-to-generate-sine.html
http://tahmidmc.blogspot.com/2012/10/generation-of-sine-wave-using-spwm-in_10.html
http://tahmidmc.blogspot.com/2012/10/600w-50hz-sine-wave-inverter-test.html

2 other interesting articles:
https://www.wpi.edu/Pubs/E-project/.../unrestricted/MQP_Report_Final_2012-04-26.pdf
http://www.wpi.edu/Pubs/E-project/A...-190851/unrestricted/PWM_Techniques_final.pdf

If you are thinking of the non-microcontroller way, you could take a look at this:
http://www.wpi.edu/Pubs/E-project/Available/E-project-042507-092653/unrestricted/MQP_D_1_2.pdf

Hope this helps.
Tahmid.