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AC booster for startup surge (similar to grid-tie)
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jonroger:
I have a 2000W 120 VAC inverter generator that can't produce enough short term power to start some loads (eg motors).    So I'd like to build something that provides a short (say a few cycles, 50 msec) AC boost.  This is similar to a grid-tie inverter, but there is no utility grid involved.  Let's assume I understand all the safety issues.  And that I can't reduce the startup surge.

I'm looking for feedback on the design.

Small transformer based (ie, isolated) power supply creates 250VDC and stores it in a large capacitor.

Buck converter

H-bridge to invert the single ended output from the buck converter.

A micro-controller would measure the existing AC waveform to learn frequency, timing and typical voltage (at every point in the AC waveform).  Whenever (as in a few  microseconds) the AC waveform voltage drops a little below normal, the buck converter would charge the inductor and then discharge it into the H-bridge.   Repeat as needed.    If boost is provided for more than 50 msec, shut down (this helps with heat dissipation).

Feasible?   I know some $1000+ hybrid inverters have generator/power assist.  Any lower-cost off-the-shelf solutions I have missed?
soldar:
To be honest I do not think you will find a practical general solution of the type you are thinking. In practical terms the solution would be to get a more powerful inverter.

On the other hand, it depends a lot on the load. Maybe some loads can be soft-started and gradually brought up to speed. Maybe some motors could be fitted with a manual starter, like a lawnmower, so you could get it turning by hand and then apply electrical power.

So, it depends on the inverter and on the load.
unitedatoms:
There should be some low cost mechanical solution. Like a motor paired to generator across large flywheel. Or just a flywheel mod to existing generator.
soldar:
If the generator-inverter is of those small types like the Honda 2000 I can't see any practical way of mechanical boost. Possible maybe yes, but not practical.

And if the limitation is in the electronic inverter then it would not work anyway and you just need a more powerful model.
coromonadalix:
You need to find a suitable inverter who accept startup motor spikes .... i know they are out there but easier said than done, i had one in my old company truck, it was a 3kw   but I never knew the brand :(
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