The Application And Experiment Research On Pulsed Power Switch Of Capacitor-based Power Supply In Electromagnetic Railgun

The electromagnetic(EM)railgun is a research focus at home and abroad for its all-electric mode,hypervelocity and wide applications.As an important part of EM railgun system,the pulsed power supply(PPS)is used to provide the energy needed for the launch.The amplitude and pulse width of the discharge current can be effectively controlled by the power control device,so as to meet the requirements of launcher and achieve the launch speed beyond the conventional gun.In this paper,the application of pulsed power switches in capacitor-based power supply for EM railgun are studied.(1)Research on a triggered vacuum switch(TVS)PPS.The structure and triggering characteristics of TVS and the structure,conduction characteristics and trigger circuit of triggered vacuum switch with multi-rod electrode(MTVS)are described.To meet the needs of small caliber EM railgun research,a 2 MJ PPS which uses RVU-43 TVS was developed.The PPS is of multi-module parallel structure and composes of 17 118 kJ capacitor-based pulsed power modules.Introduces the module structure and components,using high voltage capacitor direct discharge method designed TVS trigger circuit,describe the control,charging and measurement system of PPS.The circuit simulation model is established,through simulation and experimental comparison to meet the design requirements.The PPS rated operational voltage is 13 kV.The maximum short-circuit discharge current of pulsed power module is about 52.45 kA.Application of PPS to the small caliber railgun launching experiment,under the condition of synchronous discharge,the influence of different charging voltage,inductance and railgun structure on the launch performance is analyzed.The launch uniformity experiment under the condition of synchronous discharge was carried out.(2)Application of PPS with reversely switched dynistor(RSD)in EM railgun.The structure,working principle,commutation characteristics and precharge trigger circuit of RSD are described.A capacitor-based 1 MJ PPS with RSD is developed.The PPS is of multi-module parallel structure with 16 64 kJ pulse power modules,adopts a compact and integrated design as well as built-in functions,such as charing,control,protection and measurement.Introduces the module structure and components,using pulse transformer designed RSD trigger circuit.The circuit simulation model is established,through simulation and experimental comparison to ensure meet the design requirements.The opertional voltage of PPS is 18 kV,the maximum short-circuit discharge current of pulsed power module is about 60.02 kA,and the short circuit synchronous discharge peak current is 829.88kA at the charing voltage of 14 kV.Through the experiment of small caliber railgun,analyzed the electrical parameters in the same amplitude,the effects of synchronous discharge and sequential discharge on the launching peroformance of railgun are studied.The matching problem between discharging sequential and launch process is studied.The launch uniformity experiment under the condition of sequential discharge was carried out.(3)Research on a thyristor larger energy storage PPS.The structure.,working principle,the voltage sharing protection circuit and trigger circuit of thyristor are described.A 13 MJ PPS which uses thyristors was developed.The PPS is of multi-module parallel structure and composes of 260 50 kJ capacitor-based pulsed power modules.The circuit simulation model is established,through simulation and experimental comparison to ensure meet the design requirements.The opertional voltage of PPS is 10 kV,the maximum short-circuit discharge current of pulsed power module is about 67.03 kA.Through the observation of the discharge current waveform,the fault module can be quickly detected.The fault waveform of each component in the module is analyzed.The PPS is used in the medium caliber railgun launching experiment.When the charging voltage is 8.5 kV,the PPS is increasing,of which output 1.29MA current,pulse width of several milliseconds,rapid rising and flat-topped wave.The application of TVS,RSD and thyristor,respectively comparative analysis and discussion of the switch structure,conduction mechanism,trigger characteristics and the current rising rate.It is feasible to use three kinds of switches,and thyristor is more suitable for the EM railgun PPS.The diode series and parallel circuit model of MJ pulse power module is established.According to the working state of the switch,the discharge process is diviede into three phases,and the feasibility of-the diode series parallel connection is verified by simulation and experiment.(4)Research on capacitor charging power supply(CCPS)and voltage maintaining technololgy based on IGBT.Through the comparison and analysis of various charging methods,it is considered that the series resonant high-frequency constant current charging method using insultaed gate bipolar transistor(IGBT)is most suitable for the PPS of railgun.In order to meet the requirements of 250 kJ pulse power module with high energy storage density and short time with high continuous working times,a compact CCPS is developed.The railgun system which adopts a larger scale capacitor-based PPS cannot satisfy the demand of high launch consistency.After analyzing the experimental data,it is found that the capacitor voltage dropping after charging completion is one of the important factors which affects the launch consistency.The energy will loss more than 5%when the time of waiting for launch is about 12s.A voltage maintaining method which can effectively resolve capacitor voltage drop and ensure PPS working voltage relatively stable during launch is given.The charging system of a 13MJ PPS has been improved based on this method and the scattering of discharge voltage maintains within 1%.It is proven that the proposed voltage maintaining method,which can improve the launch consistency,is feasible and reliable.