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I wasn't going to post it here because stuff like this gets folks in a tizzy, but what the heck.
Out of sheer curiousity, I got this working in spice. I used a hysteresis controlled buck converter, removed the catch diode, and rectified the control loop elements. (I used both current and voltage). Since it's a hysteretic buck converter w 90 deg phase shift, it should be bulletproof. I used an oscillatorinto an RS flipflop for the delay element (time hysteresis).
It seems to work nicely. Limiting either current or voltage to preset limits. I ran with a fixed limit, but if you used a trimpot scaled version of rectified ac, you could have a scaled sine wave.
I built my sim out of discretes, using a dual opamp apiece for the precision rectifiers, a comparator per limit, and an RS flipflop. Lots of 67 cent parts implement current mode buck converters. (but I dont have spice models for them. I find my discrete model easier to play with programmable limits too)
Since there's no catch diode, and precision rectifiers are used, this should be able to regulate to within less than a diode drop of incoming ac. Make sure you use a bipolar output filter cap.
Out of sheer curiousity, I got this working in spice. I used a hysteresis controlled buck converter, removed the catch diode, and rectified the control loop elements. (I used both current and voltage). Since it's a hysteretic buck converter w 90 deg phase shift, it should be bulletproof. I used an oscillatorinto an RS flipflop for the delay element (time hysteresis).
It seems to work nicely. Limiting either current or voltage to preset limits. I ran with a fixed limit, but if you used a trimpot scaled version of rectified ac, you could have a scaled sine wave.
I built my sim out of discretes, using a dual opamp apiece for the precision rectifiers, a comparator per limit, and an RS flipflop. Lots of 67 cent parts implement current mode buck converters. (but I dont have spice models for them. I find my discrete model easier to play with programmable limits too)
Since there's no catch diode, and precision rectifiers are used, this should be able to regulate to within less than a diode drop of incoming ac. Make sure you use a bipolar output filter cap.
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