831eb72a_es_content_from_Machine_Design__Induction_motor
[0] SPEED [PMAC] VFD-driven PMAC motors can be used in nearly all induction-motor and some servo applications • Typical servomotor application speed — to 10,000 rpm — is out of PMAC motor range [Servomotor] Reaches 10,000 rpm • Brushless DC servomotors also operate at all speeds while maintaining rated load [Induction motor] 
Less speed range than PMAC motors • Speed range is a function of the drive being used — to 1,000:1 with an encoder, 120:1 under field-oriented control
The difference between AC induction, permanent magnet, and servomotor technologies | Motors/Drives content from Machine Design
Induction motor