Sine wave power inverter

[BrianT]

Take a look at Don Lancaster's site at www.tinaja.com. Search for MAGIC SINEWAVES and you will find information on how to build very low harmonic sinewaves.

HTH

Brian

[mincing]

Hi friends,

I have difficulty in seeing the bridge driven through with sinePWM.

I have built everything but the bridge is getting shorted when I try to run the inverter.

Any Ideas how to achieve dead time control in Software.

Sougata are you active?

[sougata]

Hi,

I am hardly getting time to get into the forum and I know I am missing something or the other.

Mincing,

Try to use a resistive load at the output of the bridge and inspect the i/o signals with a scope. Sometimes improver gate drive and/or switch off spike can kill MOSFETs. Please post the schematic and code snippets I will try to help if it is within my scope/knowledge. I am not as active now but you can count on every other member on this forum. Far far better than me.

If you find that you cannot reveal the code/schematic due to commercial problems you can pm me. Again I would try, no commitments.

[mincing]

Thanks for the reply!

I understood that the current drawn(peak current ) is actually higher than what is seen on front panel meter of the Power supply I used.

Do you have any calc. for peak currents that flow in to the bridge?

Actual current or Dc current is only about 1.5 to 2Amps but peak is over 5Amps. at about 15 to 20 V on no load with a transformer connected.



Also what happened to your Double conversion Inverter. I have some documents ,I like to forward to you on the subject.
I am not sure if I can post them here, give me your mail ID I 'll forward the same.

Any one who wants to build HF inverter.

Thanks again!

[mincing]

Hi sougata,

Hope everything is fine !

I have difficulty in reading the feed back and adjusting the PWM.
Presently I am reading a DC proportional to the output voltage.PWM is continuously adjusted and checked with the feed back.
However the moment ckt enter the closed loop out put becomes unstable.It keeps changing continuously.

Could you please throw some light on this./

Thanks,

[sougata]

Hi,

I think I have not come across any schematics, code snippets. I don't even know which PIC at what Fosc you are using. May be I missed something as I am not regularly visiting this forum. Details...Please.

[mincing]

Dera Sougata,

I have attached a simple block diagram of Inverter I am working on.

Hope this would give an Idea of my circuit.

Kindly suggest what should be feed back routine.
We are using C with MPLab.

Thanks and waiting for your reply

[sougata]

Hi,

I am not an expert on C (uNsUrE of my expertise of PBP aswell ) so may be cannot help much with the code (which has not been posted ) but here are some tips.

According to your schematic:

1. Feedback is from one cycle only (not recommended)
2. Driving through inverters means both MOSFETs doing PWM (wasting energy)
3. Use Flux reset when changing phase
4. Be sure that the computed PWM is not eating up cycles and resulting in uneven spread of the modulating PWM

Please report what happens when no feedback is used. Use a lower duty cycle lookup table to ensure that your MOSFETs are not fried due to full drive. Or use a lower input supply to the Bridge.