Study On The High Negative Voltage Pulse Power Supply For ECRH

The world has accepted the view that the controlled nuclear fusion, with its unique features in safety, cleanliness, and virtually unlimited fuel availability, will be one of the major energy source for future generations. The study on controlled nuclear fusion is sure to be an important direction of the exploration of new energy sources in energy industry. TOKAMAK is one of the nuclear fusion experimental facilities and has accepted wide attention.In TOKAMAK, three conditions-the plasma temperature, the plasma density and the plasma energy constraint duration-must be satisfied prior to reaching the fusion ignition of plasma, among them the plasma temperature must be raised over 10KeV (leV=10000). In order to heat the plasma to pass this critical temperature, a number of heating methods have been experimented and the Electron Cyclotron Resonance Heating (ECRH)is one of the major methods. In the implementation of this method, a cyclotron generates electron cyclotron resonance microwave beams for the plasma heating, and a tetrode-based high negative voltage pulse supply is a key support to the cyclotron's functioning and good performance is highly required.The main concern of the dissertation is the study on the high negative voltage pulse supply. According to the supply's control requirements and the nonlinear characteristics of tetrode, and incorporated with mathematical analysis and simulation, control theory and control system design, a high performance ECRH system is realized. The dissertation work may be described as follows:1. Based on an analysis of the control characteristics of the giant tetrode, a curve fitting method is proposed to deduce the nonlinear mathematical model of giant tetrode.2. Based on the mathematical model, the behaviors of the high negative voltage power supply using PI regulator with forward-feed and under different working conditions were simulated. By adjusting controller parameters, satisfactory simulation results were achieved and thus the validity of the models was confirmed.3. A PI regulator with forward-feed was designed and experimented with different references and loads (using resistors instead of cyclotron) were performed. Under different working conditions satisfactory step responses might always be obtained by adjusting the regulator's parameters.4. With a big deal of simulations and experiments, it was proved that the variable structure PI regulator with forward-feed may be used in power supply's controller, while the controller parameters has relations to the working conditions of the supply. The mathematical relation between the controller's parameters and the supply's states my be found through simulations and curve fitting, and the computation amount of parameter estimation of the variable structure controller may in turn be reduced, thus make it possible the implementation of the digital controlof the power supply.5. The way of digital control of the negative high-voltage pulse power supply for ECRH is discussed.6. The protection of each component of the supply was studied, the corresponding protection circuits were designed respectively. Experimental results proved that the protection circuit provided reliable measure for safe running of the system.7. The electromagnetic compatibility of the supply was studied, and the interference on the supply's controller of electrostatic and magnetic field induced respectively by high voltage and high current of wires were analyzed. Some effective measures were taken for shielding and interference suppression.8. According to the different demands of test/operation of the supply, a PIC micro controller based Gate signal generator is designed.