Research Of Magnetic Bearing Control Strategy

The magnetic bearing is a new type of non-contact,high speed and low loss bearing.It has been widely used in vacuum,leveling machinery,medical and other important fields.Because of its broad prospects for development,magnetic levitation bearing control system has been developing in the direction of low-cost,high-performance and high-reliability.The research of algorithm is becoming modern.In this article,a magnetic levitation bearing with five degrees of freedom is discussed and studied from the four parts of the control algorithm,hardware design,software design and experiments.Firstly,the mathematical modeling of magnetic levitation bearings was set up,then the PID control algorithm of axial magnetic levitation bearings was studied.Further,the back-stepping controller was designed,based on the backstepping-nonlinear theory of magnetic bearing system was carried out.The validity of the algorithm was verified by MATLAB simulation.Meanwhile,the perturbation power under the rotor rotation state was simulated according to the system parameters,and the anti-perturbation ability of the algorithm was verified.Secondly,the magnetic levitation bearing control system was devised.Digital control system design in the hardware was completed based on the DSP.According to the system performance requirements,suitable core device were selected,including the controller,sensor and power amplifier three modules.We focused on the PSIM simulation research of power amplifier and its drive circuit.The results verify the reliability of the circuit,based on which we completed the circuit design of the whole system.Thirdly,completed the design of main program,mode/number conversion,and pulse width modulation depending on CCS7.2.0 platform,including the initialization and configuration of each module,as well as the design of the PID control algorithm sub-functions.Finally,the experimental platform of magnetic levitation sphere was built up.The PI current control experiment was accomplished by the hand-made inductive coil.The result shows that the current response is fast.The stability and anti-perturbation ability of the system are good,and the results verify the reliability of the hardware circuits and software programs.