As the converters typically work with an intermediate DC circuit at (root)2*ACvoltage, it is not very difficult to realise. DC is then switched according to what the motor needs, voltage and frequency can (but not necessarily) be varied in wide ranges as long as the motor survives it. It is a price, space, and EMC discussion.
(edited for Germanism)
[This message has been edited by Wolfgang (edited 02-03-2006).]
