A regenerative braking controller for an AC motor. To determine an electromagnetic torque for slowing or stopping the motor, the regenerative braking controller accesses a lookup table to retrieve a braking torque value corresponding to a current estimate of rotor velocity. The retrieved braking torque may correspond to a maximum or minimum torque level at which regenerative braking will occur at the current rotor velocity, or to a torque level at which charging current during regenerative braking will be maximized. If an external mechanical brake is present, the regenerative braking controller can forward an external braking torque signal to a controller so that the mechanical brake can apply the remainder of the braking force beyond that indicated by the regenerative braking torque. A method for establishing the braking torques to be stored in the lookup table is also disclosed.