Your website looks great, i like the new layout your using for pages like the "circuit board development" I hope it all works out good for you


I just got back into my inverter project yesterday.... I finally recieved the high flux 3" cores i ordered 5 months ago (backorder) and my test inverter still works the same as ever... I had to reassemble the signal generation part still on a breadboard. 
The only thing im dissapointed about is the output filter.... it still doesnt work right... and i dont know enough about magnetics to know why, it overheats in about 30 seconds with minimal load... which is about the same as when i was using 6" iron powder cores for the filter... its an LC filter, with 450uh at 15 turns on my new core... the capacitance doesnt seem to change things at all, current through the inductor is the same if i cut the capacitance in half, starting at 35uf. I measured the current through the inductor at 7.5 amps with the +/- rails only at 100v (170v normal). If i use less inductance by lowering the turns the current just goes up... im assuming the core flux would be going down though, at the expense of wire heating.... ahh i really dont know. I was measuring current by hooking my meter in series with the inductor, it might be measuring peak current. im not sure... 
I did get some scope waveforms of the current with a sense transformer, they show the current ramping up and then crashing down at each cycle (19khz) with the whole thing modulated at 60hz ill have to send you a pic tomorrow.

Id apprecieate any insight... and ill be online tomorrow


Chester Lowrey

Chester's Electronics Lab
http://hot-streamer.com/hilo90mhz/


Im back on the project !! hehe

Well i finally got my 3" high flux toroids that were backorderd 4 months :P but very unfortuantely they dont work any better then my previous 6" iron powder cores that cost the same ammount ($15) :|  
ok... The cores are for the output filter (LC type)of the inverter, the filter must remove the 19khz carrier frequency leaving only the 60hz. But i think i was going at the filter design all wrong from the beginning, like assuming that i needed the same type of filter you would use on your 60hz line to take out interference; very wrong. 

Now i think of the half bridge inverter more as a switch mode power converter, and the inductor then must be able to .... whats the word.. handle the 19khz carrier, and not just turn it into heat (like the iron powder was doing)

This picture shows the ouput section of the inverter.. and the filter: [url]http://www.hot-streamer.com/hilo90mhz/electronics/Inverter/inverter_new/inv.jpg[/url]

I have a storage scope with a spectrum analyzer so i can see how well the filter is removing the 19khz carrier and just with the scope look at the output ripple.

with the iron powder the 60hz output is at 20db and the 19khz carrier at -20db
with the ferrite the 60hz is at 20db and the 19khz carrier at - 40 with all the other interference lower aswell.

Does this sound like an acceptable ammout of output ripple? i can still put more filters on the output to lower it even further, im wondering how much carrier signal real inverters have in the output.

Do all my assumptions about the inductor sound plausable? I really dont know too much about magnetics, and all the calculations are pretty daunting.  I know I searched all over the interenet for info on what type of material the inductor core should be made out of for this type of filter... and never found any core material specification, they only list inductance. But the material seems just as important or even more important.