Abstract—Because of its structural characteristics and the "zero drive" driving mode, the permanent magnet synchronous linear motor system is more susceptible to the influence of external disturbance and parameter changes, without any intermediate link buffer, which will directly affect the speed stability and positioning accuracy of its servo system at low speed. And the linear motor is a highly fast dynamic system, its starting and braking process is only tens of milliseconds. Therefore, under the condition of meeting the control requirements of the motor, it is the premise of selecting the control strategy that the main disturbance can be suppressed, the control instruction can be delayed without delay and the overshoot tracking can be suppressed. Fractional order PID is the inheritance and development of integer order PID. The fractional order PID controller is not sensitive to the change of its control parameters and the change of the system parameters of the controlled object. As long as the parameters change within a certain range, the fractional order PID controller can is excellent in control effect and has strong robustness. The fractional order PID itself also has filtering function. The fractional order differential term and integral term are calculated on all the current points, so that the control accuracy is well guaranteed. The simulation results show that the fractional order PID control algorithm can solve the contradiction between the stability and the rapidity of linear motor.

Fractional order， Stability， Rapidity， Servo system