Kirk Wallace wrote: > I would think > an Aurdino like processor could measure the voltage and current on each > phase and switch capacitors in or out as needed. > This is a lot harder than it sounds. Connecting two capacitors with different voltages on them together leads to nearly infinite currents. This would probably be even worse to the CNC drives. > It may be that a the load range could be wide enough for a normal fixed > capacitor rotary converter to work fine. > That is probably the only way to make this work. > My take on flywheels on generators, motor-generators and rotary > converters is that energy can be stored in the flywheel and quickly > released as the load changes, keeping the output frequency more stable > and react to a load change more quickly. > > Also an induction motor can be made to work as a generator if a circuit > is used that can set up an initial field in the rotor. This might save > having to buy an alternator if a motor is at hand. > > But, getting the proper excitation on an induction alternator is tricky. Generally these are set up in cases where infinite free power is available, namely micro hydropower systems. > It is also my understanding that a rotary converter always has correct > voltage wave phase timing. Assuming that sufficient excitation of the rotor is provided, yes. That is part of the job of the "balancing" capacitors, to draw enough reactive current to excite the rotor. > The single phase input drives one phase of > the motor and one phase of output. The other two output phases come from > the the other two motor phases as the motor coasts and acts like a > generator. It seems to me the motor's coil geometry determines the phase > timing in this situation. > > A VFD might be another solution. Just keep it at 60Hz, but make sure the > VFD switches the power to the load, and make sure there are no switched > loads on the output. > VFDs provide 400 V square waves at some switching frequency, the average of the PWM duty cycle averages out to make the motor winding think it is a 60 Hz sine wave. But, electronics will likely be damaged by a VFD's output.
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