On the evolution of AC machines for spindle drive applications

In the field of AC spindle drives, the induction motor is widely used. Synchronous solutions (reluctance, interior permanent magnets) are often suggested to overcome some drawbacks of the induction motor. The different options are compared by considering the machine torque-density and the inverter power size needed for a given constant-power speed range. It is shown that an axially laminated reluctance motor gives more torque density than the induction motor but requires nearly the same inverter size. By adding a proper quantity of permanent magnets, the inverter size can be greatly reduced. A comprehensive discussion of this subject is given. The goal is to find a design solution that is optimal for the whole drive.>