How many times of a frequency of a PWM can properly generate a sine wave to drive a motor?
In the early days of VFDs, PWM was successfully used to control motors at less than 10 times the frequency of the synthesized sine wave. At that frequency, motor losses were increased a little, but careful selection of motor ratings to suit the duty compensated for that. The acoustical noise made by the motors was ok for factory environments.

PWM at 30 or 40 times motor frequency is sufficient to reduce motor losses to an almost insignificant increase above pure sine wave losses.

Offering a customer adjustment in the range of 30 X to 300 X provides the opportunity to find an operating point at which acoustical noise is not a problem. Operating in the upper end of that range may come at the cost of reduced VFD efficiency and the need to upsize the VFD for a given motor. As devices with reduced switching losses become more competitive, higher PWM multiples may become more common.