Research On The Excitation And Discharge Control Method Of Air-core Compensated Pulsed Alternator

With the rapid development of new concept weapons,the demand for compact and light-weight high power pulse supply is becoming more and more urgent.The air-core compensated pulsed alternators can achieve a high level of energy density and power density and has attracted more and more attention.In this dissertation,an air-core compensated pulsed alternator is designed,whose electromagnetic characteristics are analyzed and simulated.The working principle of the air-core compulsator is introduced,which is similar to other kinds of compulsator with compensation windings.The electromagnetic design method and some configure selection basis of air-core compulsator are introduced briefly.The finite element simulation model of the compulsator is established in Ansys Maxwell,which is used to analyze the compulsator's steady-state electromagnetic characteristics,the self-excitation process and the discharge process.Considering the current coupling,the rotor speed change and the variable load resistance characteristics,the mathematical model of the self-excitation and discharge process are established,improving the simulation efficiency and flexibility significantly.The accuracy of the mathematical model is verified by the co-simulation result of finite element software-Ansys Maxwell and Simplorer.To solve the self-excitation problem of two-phase compulsator,four kinds of excitation scheme are proposed,namely single-phase armature excitation,two-phase series excitation,two-phase parallel excitation and series-parallel excitation.The characteristics of each scheme are analyzed.The theoretical analysis and simulation results show that using the series-parallel scheme can maximize the excitation efficiency and reduce the loss during excitation process.The characteristics of three typical kinds of loads for compulsator: electromagnetic rail guns,flash lamps and electro-thermal chemical guns are analyzed respectively.Their requirements for pulse shape are significantly different.According to their load characteristics,the corresponding discharge model is established respectively.The pulse shaping technology is studied.Under the condition of short-circuit discharge,the influences of ignition angle and series inductor on the single-phase pulse are studied.Moreover,the diversity of two-phase parallel discharge pulse waveforms under different ignition angles is verified.The discharge pulse shape optimization problem is studied.Different optimization indexes are proposed for different loads to quantify the fitness of discharge pulse,transferring the pulse shaping problem into function optimization problem.For electromagnetic rail guns,the optimization index is the “acceleration ratio” of the projectile,which is the ratio of maximum acceleration and average acceleration during launch process.By expanding the concept of acceleration ratio,this index can be applied on flash lamps.For electro-thermal chemical guns,the concept of “shape variance” is proposed to measure the pulse shape.Simulation results show that the optimization indexes proposed in this paper is effective.With the help of intelligent optimization algorithm,we can get the optimized discharge pulse for different loads.