Thrust Fluctuation Analysis And Suppression Strategy In Permanent Magnet Linear Synchronous Motor Controller

Linear motors convert electrical energy directly into linear motion, eliminating all intermediate transmission links (such as screw, gear, etc.) and provide direct linear drive. Compared with conventional rotary motors, because of no middle transmission links limitations and disturbance, the linear motors has a large thrust, high speed, high precision, fast response speed and at high speed to pinpoint the characteristics, so the linear motor has started to become the main components of high speed and high precision CNC equipment. However, the linear motor has a disadvantage what the thrust is big fluctuation, especially at low speed, thrust fluctuations may even cause resonance, thereby worsening its servo operating characteristic (such as location tracking accuracy), therefore, the thrust fluctuations of linear motor is one of the main contents of its operating characteristics analysis and study. Paper to suppress the thrust fluctuation of permanent magnet synchronous linear motor as the core, analysis the factors which cause the thrust fluctuation of permanent magnet synchronous linear motor, and then for the thrust fluctuation which caused by dead-time effect and positioning force, the paper proposed the corresponding compensation and control strategy, and its experimentally verified.Firstly, on the basis of understanding and analysis the structure and working principle of permanent magnet synchronous linear motor, the paper respective the mathematical model of permanent magnet synchronous linear motor, based on field oriented vector control strategies and space vector pulse width modulation techniques for analysis, build the three closed-loop control structure of permanent magnet synchronous linear motor servo control system. According to the control block diagram and in the Matlab/Simulink simulation environment, the paper builded a simulation model of permanent magnet synchronous linear motor servo control system, the simulation results show that the system control algorithm is feasible and effective.Secondly, the paper analysis the factors which caused the thrust fluctuation of permanent magnet synchronous linear motor, and determine the ripple disturbance and positioning force disturbance (ends cogging force and resultant force) is the main cause of the thrust fluctuation of permanent magnet synchronous linear motor. For the ripple disturbance, based on this point of view which to improve the performance of the inverter, A dead-time compensation algorithm based on disturbance voltage observer was presented for the dead time effects of the PMLSM servo control system, the simulation results show that this method significantly reduces the phase current waveform harmonic content, while effectively suppressed zero current clamp phenomenon; For the positioning force disturbance, the paper uses Fourier curve fitting positioning force curve measurements obtained by fitting the fitting formula based on current compensator design thrust, while the design of a disturbance observer thrust ripple compensation other disturbances caused by, the simulation results show that the method is effective.Finally, based on the above analysis, established that the core of the permanent magnet synchronous linear motor servo control system hardware and software platform for control strategy proposed experimental verification, the experimental results show that the servo control system design is feasible and effective, Permanent magnet synchronous linear motor thrust fluctuation can be effectively suppressed.