Research On Modeling And Control Of6-DOF Magnetically Levitated Motor

Magnetically levitated planar motor has simple construction, quick response andhigh accuracy performances. And it is used in the field of lithography machine sixdegrees of movement widely. Six degrees magnetically levitated planar motor is actedas research object, the forces and torques acting on the moving part were modeled basedon analyzing the flux density distribution of magnet array. Direct wrench-currentdecoupling method is used to achieve the decoupling of magnetically levitated planarmotor. Controllers with PID control algorithm and improved repetitive controlalgorithm are designed. Simulations are executed respectively to validate the feasibilityof the whole control structures and algorithms.Firstly, using two methods to deduce the magnetic flux density distribution ofHalbach array, and then the harmonic model of it is confirmed. According to theanalysis of harmonic model with the Lorentz Force Law, the problem of the acting forceand torque of the Halbach permanent magnet array magnetic field to unicoil was solved.After that the force model and the moment of force model were constructed. Accordingto the action and reaction, the electromagnetic forces and torque acting on theHalbach-permanent-magnet-array moving part can be achieved.Secondly, to eliminate the disturbance torque when using the dq0decouplingalgorithm, the coupling relation between the input control current and outputelectromagnetic force and torque of moving-magnetic type planar motor was analyzed.Using the force screw decoupling algorithm method, the effects among the current,electromagnetic force and torque were eliminated. The motor system has goodstableness and performance.Finally, the simulation model was constructed under Simulink. By doing so, theforce condition when the Halbach-permanent-magnet-array was used as rotor wasanalyzed. Furthermore, the kinetic model of permanent magnet array rotor wasconstructed, and it was combined with the electromagnetic force model and torquemodel. For being far from the nanoscale-positional-accuracy-requirement when usingthe PID feedback arithmetic, a modified repetitive control algorithm to cooperate withthe PID was proposed. Then position trailing error of every degree could meet thenanoscale standard. So, the use of modified Maglev Controlling Method in controlling6-DOF magnetic levitation motor was proved available and correct.