Analysis And Control Of Permanent Magnet Synchronous Linear Motor

Comparing with the traditional indirect drive system--"rotary motor + ball screw", permanent magnet synchronous linear motors (PMSLMs) can produce linear motion directly. With the advantages of high speed, high precision and high thrust, PMSLMs have wide application foreground in many fields such as high-performance manufacturing equipment, precision measuring instruments and so on. The dissertation focuses on the analysis and control of PMSLMs. In which, the electromechanical coupling model of PMSLMs is established; an efficient calculation method of magnetic field, and an accurate simulation method are proposed for PMSLMs; a new vector control method is put forward for the non-sinusoidal back-electromotive-force (back-EMF) PMSLMs. The software and hardware of control system are designed and implemented, at the same time the proposed methods are validated by experiments.Firstly, based on the Maxwell equations of electromagnetic field, the basic theory and analysis methods of PMSLMs are described. With the energy analysis method of electromechanical coupling system, the force equation is derivated, and then the electromechanical coupling model of PMSLMs is established. Thus, a theoretical basis is provided for the magnetic field calculation, mechatronic system simulation, and control system design and analysis.To solve the 2D constant magnetic field of PMSLMs, the 2D constant magnetic field boundary value problem and finite element method are described. And the forces caused by the endding effect and the slotting effect of PMSLMs are calculated respectively. Then, the conformal mapping (CM) and the numerical Schwarz-Christoffel (S-C) mapping are described. The punctual curren equivalent model of PM is established considering the PM's shape, the invariance of punctual current magnetic field boundary value problem under the conformal mapping is analyzed. The solution of complex slotting air gap magnetic field of PMSLMs using conformal mapping is derived, and the effects of PM shape on PMSLMs are analyzed.Precise dynamic simulaition of PMSLMs can't be carried out using the ideal model. Considering the effects of non-ideal structure on the PM flux linkage, inductances, cogging force, a phase variable model based on the numerical calculation of magnetic field is proposed for PMSLMs. The state equations of phase variable model are derived. The S-function simulation model of PMSLMs is established based on the spline interpolation of inductances, cogging force, and PM flux linkage using Simulink/SimpowerSystems, and the model is verified with experiments.A general vector control principle of surface-mounted permanent magnet motors with arbitrary back-EMF waveform is presented. The principle is derived from the force equation in the dot product form of the current vector and the permanent magnet flux linkage derivative vector. Based on a new d'q' reference frame considering the effects of PM flux linkage harmonic, a new vector control method is proposed for the non-sinusoidal back-EMF PMSLMs. According to periodic disturbances, the cogging force feedforward compensation and PI speed controller with repetitive control compensation are used.The control system is designed and implemented based on DSP+FPGA+IPM hardware architecture. And the validity of proposed analysis and control methods are verified by experiments.