Ed Huntress fired this volley in
:

I would think there would be some inexpensive active filters to smooth
those outputs into something very close to a sine wave. But I've never
dealt with any kind of filters at 60 Hz, so maybe there are some
limitations of which I'm not aware.

There is: It's called a "motor-generator". 'Makes VERY close to a sine
wave. OH... and if you use one, you can do away with the inverter to begin
with! G

Lloyd