Research On Modeling And Control For High Current Electron Gun Based On T-S Fuzzy Model

The electron irradiation accelerator is used as an electron source for irradiation processing and it has attracted attention gradually with the development of irradiation industry. The market demand for electron irradiation accelerator keeps increasing and it promotes the technical innovation in electron irradiation accelerator fields. The main research content in this thesis is about the modeling and control for the high current electron gun system based on Takagi-Sugeno?T-S? fuzzy model. The security and stability of the electron gun control system are very important for stability of the accelerator's electron beam and even the whole accelerator.From the aspect of modeling and control, this thesis investigates the applications of fuzzy control for LaB₆ high current electron gun control system. It mainly consists the following contents.?1? Based on T-S fuzzy model, we research on offline identification for nonlinear system. A hybrid quantum differential evolution algorithm?HQDE? is proposed. It uses quantum bit?Q-bit? encoding scheme to generate the initial population and updates the population using the operators in quantum-inspired differential evolution?QDE? and gene algorithm?GA?. Together with fuzzy c-means clustering algorithm and recursive least-squares algorithm, it is used to obtain the fuzzy model of nonlinear system. And the problem between accuracy and rapidity in modeling is also discussed. On the basis of above research, we obtained the T-S fuzzy model of the LaB₆ electron gun emission characteristics, which approximates the dynamic system very well.?2? The stability analysis and controller design of discrete-time fuzzy systems based on T-S state-space model are investigated. The controller is designed using parallel distributed compensation?PDC? and the global stability is analyzed by Lyapunov stability theory. Based on the linear matrix inequality?LMI? method, the stability analysis and controller design can be completed by solving a set of LMIs. Furthermore, the calculating process can be greatly simplified by means of mathematical software MATLAB. So it provides a solution to the realization of T-S fuzzy control in practical process control.?3? The fuzzy tracking control scheme based on discrete T-S fuzzy model is presented. The controller is designed for the tracking problem based on the identified discrete T-S fuzzy model. By leading integrator into fuzzy controller, the output variable of the nonlinear system can track the desired trajectory asymptotically. Then the method of stability analysis and controller design for discrete-time fuzzy systems can be used for the calculation of the controller parameter. It is used to control the LaB₆ electron gun system and the simulation results show that the T-S fuzzy control system has good tracking performance.?4? The H? robust fuzzy tracking control scheme based on discrete T-S fuzzy model is studied. Considering the external disturbance and noise, the proposed scheme is used to ensure the system meeting prescribed H? performance index. To deal with the condition that the state variables can not be measurable directly, the H? robust fuzzy tracking controller is designed with a corresponding observer. And the H? robust fuzzy tracking control system for LaB₆ electron gun can make the output variable track the desired trajectory very well under the condition of external disturbance and noise.?5? To realize the T-S fuzzy control algorithm, we built an experiment platform based on PC, programmable AC source, data acquisition card, etc. The whole T-S fuzzy control scheme was implemented in the PC running MATLAB. Through the test, the T-S fuzzy control system is proved to have good tracking performance. And the model-based control strategy is proved to be feasible and effective.