Technical considerations for large AC induction motors on variable frequency applications

An examination is made of those issues that must be considered when applying an AC drive. These include the following: (1) motor loading; (2) efficiency and motor losses; (3) load torque requirements and drive capability; (4) motor insulation life; (5) power factor correction; (6) bearing performance; (7) circulating shaft currents; (8) mechanical resonances; and (9) aerodynamic and magnetic noise. The authors argue that conventional induction motor design philosophies need to be modified and matched to controller and load characteristics if optimum performance is to be achieved. This requires that the entire drive system be assessed as a unit. Purchasers must ensure that the subjects addressed in this work are considered by appropriate parties supplying components to the system