[moved] sinusoidal pulse width modulation inverter

[maaxamed]

Thank you for the reply and advice

I will start with the square wave inverter first, is there a circuit I could try which would then lead on to the transformer design?

 

[BradtheRad]

This topology is a natural choice for starting out. It has just two switching components, which makes the control portion less complicated than for a full H-bridge.

I built one of these because it is easy to work with. However I had a problem with high voltage spikes because I did not know enough about snubbing techniques. I was unable to get much power from my inverter. I also burned up several mosfets.

Once you construct the transformer for this inverter, it should be possible to re-use it for SPWM.

 

[maaxamed]

With the transformer what factors would you need to take into account. such as the winding for the primary and secondary? What size would the ferriet core be.

Thanks

 

[BradtheRad]

With the transformer what factors would you need to take into account. such as the winding for the primary and secondary? What size would the ferriet core be.

This is an area where theory and experience assist toward success. Here are a few key parameters. They are not the only ones.

* Core needs to sustain desired flux intensity without saturating

* Turns ratio

* Primary winding has correct number of turns to produce desired inductance

* Primary Amperes (wire needs to be thick enough)

* Secondary Amperes (wire needs to be thick enough)

 

[D.A.(Tony)Stewart]

Brad would Litz wire help on primary?

 

[maaxamed]

So if my input was 12v and the power output was 150watts/230v. What would the core be aswell as the primary and secondary windings.

Thank You.

 

[BradtheRad]

Brad would Litz wire help on primary?

Hi Tony - This is an area where I should consult you, of course. As I understand it, Litz wire is stranded, to avoid skin effect when we want to carry high current at high frequencies. Litz wire is recommended for transformers which carry SPWM.

This means I was probably incorrect (in post #22) to suggest the same transformer made for 50/60 Hz square waves, could then be re-used with SPWM at several thousand Hertz. However if Litz wire is used in the primary, then I suppose it should be suitable. I'm not experienced at building transformers, only disassembling them.