About my pwm sine inverter

[gaetan8888]

Originally Posted by Elvee

It does work quite well, and can even be used with an old style, superposed windings transformer.
The only types that are completely ruled out are toroidals.

Hello

Yes, 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 the LC low pass filter would need a big L coil, but it would be easyer to keep my SG3524 circuit very stable.

Thank

Bye

Gaetan

[Elvee]

Originally Posted by gaetan8888

Hello

Yes, 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.

You shouldn't do that: at such low frequencies, the transformer will still be relatively "perfect", and the leakage will not be able to play its role.

This will generate high peak current and huge residues in the output.

You do not have to care about eddy current losses: what counts is the flux excursion, translated into volt/turn, and this remains constant.
When you increase the frequency without changing anything else, the peak induction decreases in a proportional manner.

The situation for hysteresis losses is different, because energy is lost for each cycle, but in practice, this is more or less compensated by the reduced induction level.

The only loss that does increase is caused by magnetic viscosity, but it remains relatively marginal.

In summary, if you operate the transformer at ~20KHz, you will incur some additional losses compared to 50/60Hz, but that will remain moderate and just requires a small derating.

[gaetan8888]

Hello

Another way to do a NFB could be using a small transformer at the output like in my new schematic.

I've also done few littles others modifications.

Thank

Bye

Gaetan

[gaetan8888]

Hello

I've found the inside schematic of the SG3524.

For those who can use it, here it is.

Bye

Gaetan