Lee Hart wrote:
There are lots of solutions. Which one is "best" depends on what you've got, what you want to spend, and how good it needs to be...
One more thing occurred to me. Here's a way to "trick" a modified sinewave inverter into producing a better sine wave.
Connect an induction (or better yet, a synchronous) motor to the inverter. Run this motor with no load on its shaft. Since all motors are also generators, the motor will try to level off the peaks and fill in the missing parts of the sine wave. It acts as a motor during the parts of the cycle where the AC voltage is too high; and as a generator during the parts of the AC cycle where the voltage is too low. So, any load you connect at the same time will thus get a cleaner waveform.
This trick is especially useful to generate 3-phase power with a single-phase inverter. You power one phase of a 3-phase motor with the inverter, and it "fills in" the other two phases.
It is also a way to get an undersized inverter to start a big motor. Normally, as soon as you connect the big motor, its starting current makes the inverter shut down. But if you start a smaller motor first, its spinning inertia generates the extra power to start the big second motor.
-- Fools ignore complexity. Pragmatists suffer it. The wise avoid it. Geniuses remove it. -- Alan Perlis, "Epigrams on Programming" -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
