Research On Key Technology Of High-precision And High-reliability Pulsed Power Supply For Electromagnetic Launch

Improving the launch accuracy and reliability of the electromagnetic launch system(EMLS)is an urgent application engineering problem that needs to be solved.The pulsed power supply(PPS)based on capacitor energy storage is the core energy driving device widely used in rail gun systems.The error of output characteristic of the PPS has an important impact on the launch accuracy of the rail gun.At the same time,the safe and reliable power supply is the premise to ensure the rail gun system to obtain high-precision driving energy.The influence of the electrical parameters of the PPS on the launch accuracy of the rail gun was analyzed firstly.A complete simulation model of the EMLS was built.The electromagnetic force,friction force,and motion equations of the rail gun were derived,and the circuit gun simulation model was given.For the characteristics of the high-power device parameters of the PPS are difficult to measure with the transient change of the discharge,frequency and time domain electromagnetic field simulations were used to obtain the transient inductance and resistance change model of the pulsed inductance.Meanwhile,the stray parameters of the power module were obtained,and the single-module power supply simulation model was established.Then a complete model of the EMLS was given,which could simulate the actual parameters such as current waveform and initial velocity in the launch experiment.Then,the influence of each electrical parameter of the PPS on the accuracy of the muzzle velocity was analyzed by using the complete model of the EMLS and the accuracy control method was proposed.It is clear that the dispersion of discharge voltage(0～-10 ‰),capacitance loss(0～-10 ‰),and external temperature change(±10℃)have the greatest influence on muzzle velocity accuracy when acting alone,and the three factors cause errors of 16‰,7.88‰ and 10.94‰ respectively.The influence of the conduction delay and the dispersion of the conduction resistance of the thyristors on the initial velocity accuracy is small.After,the error distribution scheme of electrical parameters of the PPS under the specified initial speed accuracy was proposed by combining the theoretical analysis and the actual measurement results of the relevant electrical parameters.A method of voltage compensation adjustment based on online measurement of capacitance change was proposed aiming at the loss of capacitance as the number of discharges increases,and a voltage adjustment curve corresponding to capacitance change was given by simulation.Several key technical studies on the safety and reliability of the PPS was carried out.The specific work is as follows.The first one,safety optimization analysis of the PPS topology was completed.There is the potential risk for the basic topology in parallel operation,which the single module can’t be isolated from other discharge modules when the thyristor of this module is damaged.So an improved circuit of adding protection diode device was proposed,and the feasibility of the measure was demonstrated from the circuit simulation.The second one,the electromagnetic compatibility research of the pulse power supply module was carried out.A three-dimensional transient electromagnetic field simulation model of the PPS was established,and the effects of material properties and material thickness on magnetic field shielding were analyzed.At the same time,an experimental study of the frame grounding method was carried out,and it was clarified that using the 5kΩ resistance grounding can significantly reduce the potential rise compared to the frame suspension,and the potential peak reduction was more obvious as the distance away from the pulsed inductance and copper bar,but the potential of the ground point was not significantly decreased.The third one,the electromagnetic force evaluation of the mechanically sensitive devices inside the power module was completed.The coupling analysis of the transient electromagnetic field and the structural force field was used to simulate the stress characteristics of the pulse inductor body,which provides a reference for the design of the inhibitory coating.The optimization analysis of the direction of the pulsed inductor lead was carried out,and the conclusion that the electromagnetic force suffered by the lead in the radial direction was the smallest was obtained.The stresses of the 5 mm and 4 mm copper bars at the peak value of the current flow were 32 MPa and 45 MPa respectively after calculation,which could provide a reference for the light and compact design of the module.In general,the influence degree of electrical parameters of the PPS on EMLS launch accuracy was defined in this paper,which could lay a foundation for improving the accuracy of EMLS.And how to improve the reliability of the PPS was studied,so the goal of improving the launching accuracy and reliable ability of the EMLS was finally served.