Research On Active Disturbance Rejection Decoupling Control Of Inverter Supplying Magnetic Bearings

Magnetic bearings are a new kind of high performance bearings,which use magnetic field force to make the rotor float in space,so that the stator will not be in mechanical contact with the rotor.Compared with the traditional mechanical bearings,the magnetic bearings have many incomparable advantages,such as long life,high speed,high precision,no lubrication,low loss and etc..Thus,the magnetic bearings have broad application prospects in many fields like wind power generation,aerospace,turbine machinery,industrial manufacturing and so on.At present,the universal four-pole magnetic bearings and eight-pole magnetic bearings are driven by the unipolar or bipolar power amplifiers,which have many shortcomings,such as high cost,difficult heat dissipation,high loss and etc..In contrast,a six-pole hybrid magnetic bearing(HMB)is studied by our group.It can be driven by three-phase inverter and the drive system has the advantages of small size,low cost and mature technology.However,the six-pole HMB is a strong coupling system with multi-input and multi-output.In view of the above shortcomings,under the supports of the National Natural Science Foundation of China(51675244)and the Key Research and Development Program of Jiangsu Province(BE2016150),this dissertation takes the motorized spindle of the high-speed machine tool supported by the five-degree-of-freedom(5-DOF)six-pole HMB as the research object.The main researchs of this dissertation focus on the active disturbance rejection decoupling control of the 5-DOF six-pole HMB.The main contents and research achievements are listed as follows:Firstly,the research status of the magnetic bearings at home and abroad are summarized,and the composition and working principle of the magnetic bearing system are analyzed.Then,the magnetic bearings are classified according to the differences between structures,and the characteristics of different kinds of the magnetic bearings are studied.The advantages and disadvantages of the main decoupling control technology are summarized,and the purpose and significance of the research are clarified.Secondly,the structure and working principle of the motorized spindle supported by a5-DOF HMB are analyzed.The mathematical model of the HMB is calculated by using theequivalent magnetic circuit method.Based on the derivation of the formula for calculating the levitation force,the state equation of the 5-DOF HMB motorized spindle is established and the corresponding dynamic parameters are calculated.Thirdly,based on the analysis of the basic theory of the active disturbance rejection control(ADRC),a linear/nonlinear active disturbance rejection switching control(SADRC)and its parameter tuning method are proposed.The decoupling control scheme of the SADRC for the multivariable coupled system is designed.Based on the design of a SADRC for the 5-DOF HMB,a simulation of floating,disturbing and decoupling of the 5-DOF HMB is carried out on the MATLAB.The results are compared with the simulation results of the traditional PID control in detail.Finally,the digital test platform of electric spindle supported by the 5-DOF HMB is constructed.According to the overall control method of the 5-DOF magnetic levitation motor spindle,the software and hardware of the digital control system of motor are designed with TMS320F2812 as the CPU of digital control.Taking the program algorithm in DSP as the core,the feedback signal is sampled,analyzed and processed through the interface circuit,and the current phase and size of the winding are modulated by PWM wave to realize the stable suspension the rotor.The floating and disturbance tests of the whole system are carried out by using the motorized spindle digital test platform,and the test results are analyzed in detail.