V/Hz scaling is just a bit of code. You'll be a lot more limited in how much you can apply, but going down to 200/100V and 50Hz should work fine. (Just ask the Japanese!) Even then, a 20% power usage reduction for motor loads and 30% for resistive loads is pretty substantial.
You'll do even better if you used 3 phase for the compressors driven with off the shelf VFDs.