Hopefully? Another 48vdc-240vac Toriod Inverter build.

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wiseguy Guru Joined: 21/06/2018 Location: Australia Posts: 1254	Posted: 01:06am 17 Jan 2023         poida said     KeepIS said   Looking at noise on the Inverter AC out. .. D: The transformer, choke and load are now silent at idle to 300 watts (may test limit) and zero startup noise.   E: Using a choke with "more" inductance causes a slight startup growl and the Toriod starts to get a low frequency growl even at idle.   ..  This will be very interesting to Wiseguy. He has been on a quest to quell this growl sound. It sure is, one of my last posts (30/12/22) said;   wiseguy said   "Mike I agree that my build and its trials and tribulations are a bit hard to follow as I have not presented it as a finished project as its still a work in progress.  The most recent encouraging discovery is that I unwound a couple of turns from my CHOKE in series with the Toroid to see what would happen and the grunt was about 1/3 of its previous volume" Since I wrote that I have spent zero time working on my inverter due to some other pressing projects that are currently underway. It looks like Mike has come to the same conclusion that more uH is not always better and finding the sweet spot is very worthwhile. In one of my first posts on this subject I predicted (from calculations) a value of ~ 47uH would be my starting point with a 48V supply, but unless I misinterpreted him Warp said a higher value inductance only changes the peak to peak ripple in the choke and the actual value was not too critical. Mike, Thanks for your ongoing investigations and detailed posts which as Poida correctly predicted has been of particular interest to me.  I have been a little jealous of not having the time presently to continue my quest to discover the right choke formula. The blue sendust toroids I use for my chokes were originally out of a railways Sola Basic 72V to 240V inverter, that from memory used I think 36 TO220 Mosfets, 9 in each leg !  Sendust is amazing stuff, I also thought I was doing something wrong when I tried to find their saturation point which was more like a subtle gradual curve than a knee. Keep up the good work ! Edited 2023-01-17 11:13 by wiseguy