Study On Influence Of Control Parameters On Dynamic Characteristics Of Active Magnetic Suspension Electric Spindle System

Because the active magnetic suspension electric spindle has the characteristics of ultra-high speed,high precision and controllability,it is widely used in modern ultra-high speed precision CNC machine tools.The active magnetic suspension bearing is the core component of the active magnetic suspension electric spindle system.Its supporting characteristics not only have complex mechanical and electromagnetic coupling relationship with the dynamic performance of the spindle rotor,but also closely related to the electromagnetic control algorithm and control parameters of the active magnetic suspension bearing.Therefore,how to coordinate the dynamic characteristics of the spindle rotor with the control parameters by a certain control algorithm to ensure the machining accuracy requirements of the magnetic suspension electric spindle becomes an urgent problem to be solved by the active magnetic suspension electric spindle.Therefore,this thesis takes the magnetic suspension electric spindle produced by FGAMB as the research object.On the basis of establishing the spindle rotor dynamics model,the characteristics and control parameters of the incomplete differential PID control algorithm around the active magnetic suspension bearing are applied to the requirements of the rotary precision of the active magnetic suspension electric spindle.In the selection and other aspects,in-depth research has been carried out,and the following phased research results have been obtained:First,the linearization model of the electromagnetic bearing force of the magnetic suspension bearing of the active magnetic suspension electric spindle is established.Under the premise of ignoring the influence of nonlinear factors such as core magnetization and magnetic flux leakage,the electromagnetic bearing force of the magnetic suspension bearing and the bearing air gap offset and control current are established by analyzing the force of the spindle rotor in the magnetic suspension bearing.Expression;then,based on the high precision of the active magnetic suspension electric spindle,the air gap offset of the bearing during the movement of the spindle and the variation of the control current are very small(micron order),the electromagnetic support of the active magnetic suspension bearing The force is developed by Taylor's formula,and the high-order infinitesimal is ignored to realize the linearization process.Finally,by analyzing the linearization formula of the electromagnetic bearing force of the active magnetic suspension bearing,the radial-degree-of-freedom coupling of the active magnetic suspension electric spindle system is not strong.Conclusions that can be independently controlled.Secondly,based on the engineering application requirements of active magnetic suspension electric spindle,the advantages and disadvantages of various control algorithms and their applications are compared.Based on the dynamic model of the active magnetic suspension electric spindle and the linearized model of the electromagnetic bearing force of the active magnetic suspension bearing,and considering the noise reduction requirements ofthe sensor,the low-pass filtering link is introduced,and the PID control software is used to compare and analyze the PID control performance.The influence of the incomplete differential PID control is better and the robustness is stronger.Therefore,the incomplete differential PID controller is designed and the range of values ??of each control parameter is determined.Thirdly,based on the incomplete differential PID control algorithm,the mechanical and electromagnetic control parameters of the active magnetic suspension electric spindle system are changed.The dynamic characteristics of the system under the incomplete differential PID control are verified by ANSYS Workbench software.Based on the dynamic model of the active magnetic suspension electric spindle system,combined with the mechanical and electromagnetic parameters of the system under incomplete differential PID control,the system analyzes the natural frequency and the damping of the active magnetic suspension electric spindle system.The variation of the critical speed under different control parameters;then the ANSYS Workbench software is used to analyze the modal harmonic response,and the spindle vibration mode,frequency,critical speed and spindle amplitude obtained by simulation analysis are compared with the theoretical calculation values.The simulation results verify the correctness of the above theoretical analysis.