If you have a 3-phase VFD running a 3-phase motor, and you use a leading or trailing edge dimmer on one or two of the input phases, will the VFD continue to operate normally, pulling more current from the unaltered phase(s)?
The reason I ask is that I am planning a backyard stored-water hydroelectric system with a 3-phase turbine. In order to keep things stable I will need to balance power draw across the three phases, so I need something that will draw power from only one or two phases to "take up the slack" if one or two phases are more heavily loaded than the others.
Some people have achieved this by using TRIACs on the under-loaded phases to send a variable amount of power into under-floor heating, however I live in a hot climate so don't have much use for heating.
I am wondering whether I could instead use a VFD to pump water uphill (for later use by the hydro system) but use the same TRIAC arrangement to limit the amount of power available on each phase, so that the VFD preferentially draws more power from the specific phases I wish.
I have done a little research into VFDs and they all seem to be large 3-phase rectifiers, producing DC which is then sent to the motor via PWM. It would seem that chopping the input AC waveform on only one phase would merely introduce more ripple to the resulting DC, which would be filtered out by the capacitors already in the unit.
Is this assumption correct, or would other problems be introduced by altering the AC waveform on the VFD's input?