Research Of Inertia-based Modular Pulsed Power Supply

Electromagnetic railguns have become the development direction of future artillery launching technology due to their high muzzle velocity.The key component is a pulsed power supply(PPS)that can provide short-time high current pulses.Pulsed alternators are a PPS based on the principle of inertial energy storage.It has the advantage of high energy density and has strong application potential.However,as the energy level in the projectile increases,it is difficult for a single pulsed alternator to meet the railgun requirements.This paper proposes and studies an Inertia-based Modular Pulsed Power Supply(IMPPS)composed of multiple pulsed alternator modules to solve the problem of a single pulsed alternator driving the high-energy railgun,such as machine manufacturing,current waveform adjustment,and the huge discharge torque.But so far,most of published researches on pulsed alternators is based on a single module.IMPPS raises several questions that must be answered.How to design a pulsed alternator quickly.How many modules are selected.How must the machines be connected together.How to control the discharge process.Therefore,this thesis has carried out research on pulsed alternator design and IMPPS matching design method,connecting manner and discharge process control.The main research work includes the following aspects:The design principle of pulsed alternators was studied.Based on the method of magnetic vector method and circuit analysis,the magnetic field characteristics and transient operation process of pulsed alternators are analytically described,which solves the problem of unclear mechanism of pulsed alternators due to air-core structure and transient operation,and makes machine design and analysis get rid of finite element software.The performance requirements of railguns for pulsed alternators are analyzed.The analytical relationship between the performance requirements and the design parameters is derived.The electrical load and magnetic load of pulsed alternators and its limiting factors are analyzed,which are all limited by the strength of the carbon fiber.Finally,the design flow of pulsed alternators is given to realize the rapid machine design.A 100 megawatt pulsed alternator is manufactured and tested.Machine design principle,test data,and experience have laid the foundation for IMPPS design and research.The pulsed alternator is not a standard device similar to a lithium battery,so the matching design of IMPPS has problems such as large calculation amount and difficulty in optimization.Therefore,an IMPPS fission design method is proposed.In this method,the performance requirements satisfied by single reference pulsed alternator is decomposed into n machine modules.Using the geometric similarity of pulsed alternators with the same mechanical load and magnetic load,the parameters and performance of machine module are expressed as a function of the number of modules,and the parameters and performance of the corresponding drag motor and rectifier bridge are analyzed.Finally,n IMPPS solutions that meet the requirements are obtained.Thus,the rapid design and performance calculations of IMPPS is solved.The relationship between the optimization goal of IMPPS and the number of modules is analyzed.The method of determining the optimal number of modules is given.The matching design flow of IMPPS is given.To drive the 32 MJ muzzle energy railgun,IMPPS selects the scheme composed of 6 machine modules.To solve the problem of IMPPS connecting manner,the dual machine system is selected as the basic research object.The characteristics of different connecting manners of the dual machine system are analyzed: machines are connected in series or parallel,field windings are charged independently or are connected in series,machines are connected in parallel to the ac side or the dc side.The impact of machine parameter variations on the discharge current and the dual machine system performance is revealed.The results show that the impact of machine parameter variations on the discharge current is a positive feedback.The dual machine system,which machines are connect in parallel to the ac side,is the most robust due to the self-correcting circulating currents between the machines suppressing the positive feedback.Therefore,the dual machine system selects the connecting manner which machines are connected in parallel to the ac side.The characteristics and connecting manner of IMPPS composed multiple dual machine system is analyzed.To control the discharge timing of each unit and improve the current waveform adjustment capability,each dual machine system is connected to the dc side in IMMPS.The IMPPS is a kind of generator system that needs to control its discharge process to ensure smooth and efficient operation of the railgun.For this purpose,the discharge control method of IMPPS has been studied.The discharge process of IMPPS driving railgun is theoretically analyzed,and its discharge current characteristics are obtained.The research shows that the discharge current is affected by the two types of interaction between multiple current pulses: the voltage gain effect and the current inhibiting effect.And the process of IMPPS driving railgun is a transient,electromechanically coupled process with human control factors.The problem of IMPPS discharge control is described and analyzed.The optimization objectives,optimization variables,and constraints are determined.The ideal rail current waveform with the acceleration ratio and efficiency as the optimization target is given.On this basis,IMPPS discharge control method based on rules and genetic algorithm is proposed.Finally,the weighted combination method is used to convert the acceleration ratio and efficiency dual target into a single target.The multi-target discharge current control method based on genetic algorithm is given,which realizes the smooth and efficient operation of railgun.Based on the pulsed alternator design principle and the manufacturing and test of machine,this thesis solves the theoretical problems of IMPPS through the research of the matching design method,connecting manner,and discharge control method.This result and conclusion provides theoretical guidance for the practical engineering applications of high-energy railguns.