A system and method to reduce a whirl effect on a rotation of a drill string with an AC induction motor mechanically coupled to a rotary drilling system and configured to drive the rotary drilling system and the drill string attached thereto. Additionally, the system includes an electronic inverter to generate supplied power for the AC induction motor and a controller configured to drive the operation of the electronic inverter to impose a virtual drive characteristic relating a torque output of the motor with speed of the motor, determine a desired nominal operating point, and determine presence of whirl in the drill string from torque of the rotary drilling system and speed of the drill string.