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

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Solar Mike Guru Joined: 08/02/2015 Location: New Zealand Posts: 1190	Posted: 01:02am 17 Jan 2023         poida said   This is an inherent characteristic of PWM modulating an AC sine output. Somehow near zero voltages need to be produced from very narrow PWM pulses. And at zero voltage there will be increasing gaps between the smallest available pulse widths where no pulse is required. I was reading, cannot remember where, that if the PWM pulses are centered in each 20Khz time slice period, the modulation distortion is much reduced. See sketch below. I think its much easier to produce the PWM at the start of each period, eg after timer interrupt, as in the top sketch. If the CPU timers allow an offset and the bottom modulation achieved - 2nd sketch, then distortion products would be reduced and perhaps leading to more efficient operation. Cheers Mike