Inverter poor AC voltage regulation

Author	Message
Murphy's friend Guru Joined: 04/10/2019 Location: Australia Posts: 678	Posted: 04:48am 05 Nov 2024         poida said   I would test the Vfb circuit to ensure that TP5 increases in DC voltage as the AC voltage increases going into the small feedback transformer. and Maybe watch Vfb (with the volt meter, with the meter's ground connected to the control board's ground) rise to about 2.5V as it outputs 235VAC, and then as you apply large AC loads, note Vfb. In the case of proper closed loop control, Vfb should remain stable and be 2.5V at idle AND when under load. (the 2.5V might be 2.7V or something else, no matter, it must remain stable) OK, just did this measurement, the Vfb is rock steady at 2.76V at the TP5 post for AC loads from 0W to 2910W. Here is the AC voltage drop listed: idle: 235V 135W: 234V 500W: 231V 1780W:223V 2440W:209V 2910W:196V So, it's something else that's causing it, but what? I did reconnect the AC voltage sensing to a filtered AC output. Also. one choke connection which ran close past that little sensing transformer is now a fair distance away. The dual stack transformer core came originally from my scrapped warp inverter which was wound for a 225V secondary. To this I added 20 turns to keep the flux density well under 1 Tesla at 235V. The new primary to secondary ratio is 1:9 Any clues are much appreciated.