On-line rotational inertia identification device for alternate current permanent magnet servo system and identification method

The invention discloses an on-line rotational inertia identification device for an alternate current permanent magnet servo system and an identification method, belongs to the technical field of servo motor control, and solves the problem that the conventional identification of rotational inertia of all motors is identification of rotational inertia of load mechanical systems in an off state so as not to adjust system control parameters according to current conditions of a system in real time. The device consists of a position controller, a speed controller, a torque controller, a motor and load unit, a photoelectric encoder, a differential unit, a sinusoidal signal generator and a rotational inertia identification unit; and the method comprises the following steps of: injecting a harmonic command with a lower amplitude value to a given position of a position loop motor during production run of a motor system; and extracting a motor position angle and torque control signal of a corresponding frequency component to realize on-line identification of the rotational inertia. The device and the method are suitable for on-line rotational inertia identification of the alternate current permanent magnet servo system.