The Research On Direct Thrust Force Control Of Permanent Magnet Linear Synchronous Motor

The PMLSM is widely used in various fields of industry, because of its advantages of "none transmission" simple structure, fast response speed, however, PMLSM generated magnetic flux linkage ripple, cogging, end effect, coupled with the lost of its buffer action of intermediate transmission, due to the structure characteristics of "none transmission", change of load and various disturbances will direct role in the PMLSM itself, all these problem will cause the fluctuation of the thrust, speed, stator flux, so that the performance of the PMLSM are affected greatly. Therefore, in order to solve these problems, this paper takes the permanent magnet synchronous linear motor as the research object, improve the performance of the control system through the method of combining fuzzy control method to the linear motor current control strategy, and puts forward a fuzzy adaptive control strategy, it can obviously reduce the stator flux and stator current, thrust ripple, and improve the performance of linear motor servo system.First this paper introduces the structure, the working principle of PMLSM, established the mathematical model under various coordinates, get the control equation of thrust, and providing the theory basis for the direct thrust control.Secondly, designs each part of linear motor direct thrust control system, including linear motor simulation model, inverter, speed estimate module, speed regulator, flux and thrust observer and flux regulator and thrust regulator, space voltage vector switching table, then through the Matlab/Simulink simulation, gets the response curve of the stator flux, the electromagnetic force and the speed, of the traditional direct thrust control strategy, in the constant speed constant load and constant speed variable stator current load, the response speed of the strategy is fast, but there is large pulse.Thirdly, analysis the cause of ripple, combining the fuzzy control technology, grades the output value error of thrust and flux hysteresis comparator, redesign the space voltage vector switch table, it can avoid the problem that the system may not make a correct choice in some regions of sector division space. The paper carries on the simulation and makes the results compared with the results of the simulation of traditional direct thrust control, we know that the adaptive fuzzy control can track the given value of the thrust and flux well, realize the high precision control, have a good robustness.Finally, this article proposes a method of backstepping, approach the uncertain parameters of the real system function, estimating and adjusting the system parameters and consructing the system controller through adaptive technology, decomposing the system into subsystems of low order by using the backstepping idea, making the system reach stability through the introduction of suitable control law. Design the controller of the speed, thrust and flux, design the SVPWM according to the output control voltage. The article makes a compare of the simulation results of the backstepping mothed and of the previous two metheds, by establishing the controller model. The conclusion shows that the idea of the backstepping control in this article has the obvious advantages in the aspects of the ripple suppression, improvement of the system robustness.