Research On Direct Thrust Control Of Permanent Magnet Linear Synchronous Motor

Permanent magnet linear synchronous motor (PMLSM) is widely used in industrialautomation, process development and use of energy with its unique advantages. For permanentmagnet linear synchronous motor control mechanism,building a system with stability androbustness has become the research hotspot in the control field motor. More and moreattention is attracted to Direct Thrust Control(DTC), on account of its innovative controlthought,simple motor model, the direct control method etc.. In this dissertation, the directthrust of permanent magnet linear synchronous motor control is studied.Firstly, development of the thesis of the linear motor are briefly reviewed, then introducesthe permanent magnet linear synchronous motor, summarizes the control strategy, themechanism and working principle of PMLSM. Analyzes the development status of PMLSMdirect thrust control; Establishes mathematical model of PMLSM, making a detaileddescription of permanent magnet linear synchronous motor direct thrust control theory, thenclarifies the thrust and flux control principle of direct thrust control.Secondly, in view of the traditional hysteresis control direct thrust control system hasproblem of ripple, poor stability and slow response, the dissertation presents an improveddirect thrust control method of permanent magnet linear motor, building a new PMLSMmathematical model to establish the motor model in stator flux coordinates, on this basis,realizing the decoupling control of thrust and flux. Taking advantage of the linear relationshipbetween the thrust and the load angle designing thrust control loop. Errors of thrust and flux asthe PI controller input，to generate orthogonal reference voltage component and then makinguse of the stator flux linkage vector angle transforming them to a fixed reference frame, andthe required voltage vector can be gotten from the space vector modulation instead oftraditional switch table. Load angle and rotor flux velocity calculated from the orthogonalcomponent of stator flux, do not use any position or speed sensor. Building a simulation model,verifing the proposed mathematical model and motor direct thrust control method, Thesimulation results show that, improved direct thrust control can get a quick, smooth thrust andflux response, and the control performance of the system improved significantly. At the sametime proves the feasibility and validity of the established new permanent magnet linear synchronous motor mathematical model.Finally, in order to solve the problem caused by parameter perturbation and load effectsof motor control systems, and further reduce the flux and the thrust ripple, improve theperformance and robustness of the dynamic response of the system, introducing permanentmagnet linear synchronous motor Sliding Mode Variable Structure Direct Thrust ControlStrategy, based on the established model of PMLSM. Then builds the control systemsimulation model. The simulation results show that the flux error basically stable at zero,demonstrated the system’s robustness and anti-interference ability, and system responsesquickly; at the same time, System ripple problem has been good improvement.