Fractional order PI speed controlling method of permanent magnet synchronous motor

The present invention provides a fractional order PI speed controlling method of a permanent magnet synchronous motor. The method enables a speed control system of the permanent magnet synchronous motor to get the maximal amplitude margin under the given phase margin and amplitude cross-over frequency, and realizes the control parameter integrated decision of the proportional gain, integral grain, and integration order for a transfer function of the designed fractional order PI speed controller. The fractional order PI speed controlling method of the permanent magnet synchronous motor can enable the system to get the maximal amplitude margin under the given phase margin and amplitude cross-over frequency so that the system gets larger stable reserve, thereby reducing the overshoot responded to the motor speed.