This means that the rotor voltages will be higher and currents respectively lower. Thus in the typical ±30% operational speed range around the synchronous speed, the rated current of the converter is accordingly lower which leads to a lower cost of the converter.
The rotor voltages are elevated while the currents decrease proportionally. Consequently, within the ±30% operational speed band near the synchronous speed, the rated current of the converter decreases, leading to a diminished cost for the converter.