Actually, there is no reason "in principal" that this would not work. The output phase relation (and phase count) of a variable speed drive is entirely arbitrary; I am sitting next to an 18 phase VSD right now. Solid state frequency converters are available that use essentially the same electronics as a VSD, but with significantly different details and control software.
However there are certain to be significant _practical_ issues. For example, if the VSD measures output current, it probably assumes a balanced three phase load, and might be confused by single phase loading. You might even trip some protection circuitry. The VSD output is switched at extremely high frequency (2KHz and above), and depends upon the inductance of the load to smooth out the current flow; this could cause serious problems if the load is not a simple motor.
If I had the parts on the shelf, are were willing to smoke them, then I would try running the chiller from a VSD via a transformer (the transformer to smooth the current flow and to balance the loading), and give it a good 50% chance of working.
If I had a job to do quickly, I'd just rent a frequency converter. Google for '50Hz' and you will find several.
-Jon
