The Servo Dynamic Stiffness Analysis Of Permanent Magnet Synchronous Motor Control System

The rapid development of modern industrial increasingly high demands on theservo motor. Traditional DC motor can no longer meet the requirements of modernhigh-precision processing. Many advantages of permanent magnet synchronous motor(PMSM) gradually replace the DC motor as the preferred in varieties of servo occasions.However, permanent magnet synchronous motor is vulnerable to external loaddisturbance and control system parameters, if unreasonable system parameters areselected, the servo dynamic stiffness of control system will be decreased and thestability of control system will be descended, it may even evoke mechanical vibrationand dramatically reduce the machining accuracy, therefore, analysis the relationshipbetween control system parameters and servo dynamic stiffness is necessary. On thepremise of control system stability and hardware conditions, select the optimum parameters,improve the servo dynamic stiffness. The purpose of this paper is to analyze the controlsystem parameters and the influence of the external load on the servo dynamic stiffnessfrom the frequency domain, the time domain and the linear relationship threeperspectives. The main contents of the article are as follows.Analyze the physical model of servo control system and get the mathematicalmodel from each physical model and then gradually derive the transfer function blockdiagram of the entire control system. On this basis, In this paper presented a methodbased on the Bode diagram analyzing the systemic servo dynamic stiffness. From theBode diagram we can visually see the trend of the impact of the Parameters on the servodynamic stiffness when System is of disturbed by the different frequencies.In order to get the linear relationship between the control system parameters andthe servo dynamic stiffness under particular frequency disturbance, in this paper derivedthe expression of the servo dynamic stiffness though the definition of the servo dynamicstiffness. On this basis derived the amplitude linear relationship graph between thecontrol system parameters and the servo dynamic stiffness under particular frequencydisturbance by Matlab.Servo dynamic stiffness is not a fixed value but time varying. Create a simulationmodel in Simulink so we can analyze the factors that affect the servo dynamic stiffnessand the time variation of servo dynamic stiffness under the specific control system intime domain. We can directly observe the precise relationship of the parameters andservo dynamic stiffness by this way.Finally, in this paper proposed the optimal method by combining the advantagesand disadvantages of these three methods. For a servo control system, by analyzing theparameters of servo dynamic stiffness, for disturbance of different frequencies,rationally select control system parameters and external load when design the servocontrol system so that achieve the ideal servo dynamic stiffness and Improve thepositioning accuracy.