Optimization Design And Motion Control Of Magnetically Levitated Permanent-magnet Planar Motor With Moving-coils

Planar motor can realize two-dimensional planar motions directly, without intermediate conversion mechanism. It gets the features of high accuracy, high acceleration, fast response etc.. Compared with other kinds of planar motors, magnetically levitated permanent-magnet planar motor has the advantages of simple structure, high efficiency, frictionless, and it is especially suitable for vacuum enviroment. This research addressed the magnetically levitated permanent-magnet planar motor with moving-coils. The Halbach magnetic field optimization was accomplished. The electromagnetic force/torque was modeled and the coils were optimized. A decoupling current distribution for the six degree of freedom was built and the motion controller was designed. Finite element simulations and experiments were carried out to validate the correctness of the research. The concrete content can be written as follows:Firstly, on the basic of operation principle and topology of the magnetically levitated permanent-magnet planar motor with moving-coils, the harmonic model of two-dimensional Halbach magnets array was built, and the principles of magnet parameters design were presented, which could be described as “to achieve the maximum average fundamental amplitude and minimum average relative mean-square deviation as far as possible” and “to achieve the minimum total harmonic distortion and maximum fundamental amplitude as far as possible”. Compared with previous, the finite element simulation and measured results of the experimental prototype illustrated that the presented design methods had a good inhibitory effect on the higher harmonics, especially on the second harmonic.Secondly, combined the analysis model of magnet field and the equivalent model of coils, the force of finite current elements was studied with Lorentz Force Law, and then the force/torque mathematical model of magnetically levitated permanentmagnet planar motor with moving-coils was given, which provided theoretical basis for the force/torque distribution. The principle of coil optimization was presented, which could be described as “the maximum thrust power ratio”, it obtained the minimum energy loss with the same force.Thirdly, a current control method was proposed for the six degree of freedom planar motor, which could realize the decoupling of force and torque. The influence of suspension force and moment’s exponential decay characteristic in the vertical direction on the motor’s control performance was studied, and the PID controller was designed, the results illustrated that the system with PID controller had strong anti-jamming and good robustness.Finally, the three-dimensional finite element simulation model was established with Ansoft, and the prototype test platform was built with PC + DSP28335 + driver board + prototype + sensors. The analysis results, finite element simulation results and the corresponding static experiment results of the back-EMF, suspension force and horizontal thrust were compared, the consistency of the results proved the correctness of the analytical model, the finite element simulation model and experimental prototype.