Research On High Voltage Capacitor Charging Power Supply Based On Double-transistor Forward Converter

With the rapid development of pulsed power technology in recent years, it has been widely used in military field and civilian field, such as laser engineering, particle accelerator, new weapon system, sewage treatment and so on. Because capacitor is the most common form of the energy storage system and capacitor charging power supply(CCPS) is an indispensable part of capacitor energy storage system, it is necessary to study CCPS in detail. Due to more and more pulsed power technology applications in special environment, such as strong electro-magnetic interference, high energy particles radiation and strenuous vibration, it become crucial important to research the topology and control strategy of CCPS in special environment.The driving signal of CCPS is vulnerable to interference in strong electro-magnetic interference high energy particles radiation environment, so the circuit topology with shoot-through phenomenon such as resonant converters should be avoided. Shoot-through phenomenon does not exist in Forward converter and fly-back converter, but their power level is low, so this paper selects double-transistor forward converter as the topology of CCPS.At first, this paper analysis work process of double-transistor forward converter fully and obtain expressions of the input current, charging current and duty-cycle, then this paper analysis the impact of transformer magnetic flux reset on switch tube conduction time and the relationship among the input current charging current supply voltage charging voltage duty-cycle and switch frequency. Based on the result above, a constant current charging scheme and a capacitor voltage holding scheme on the basis of the pulse width modulation is designed, then a constant current charging scheme on the basis of switching frequency adjustment is proposed to reduce charging time, and then the two control schemes are analyzed.The small-signal model of the double-transistor forward converter on the basis of the pulse width modulation is built, then the dynamic property of the charging scheme and capacitor voltage holding scheme are analyzed, and then the PI controllers in closed loop feedback system is designed. Base on the switching frequency adjustment charging scheme, the small-signal model of inner frequency adjustment ring is built, then the PI controller of outer voltage ring in closed loop feedback system of constant current charging scheme is designed. Simulation analysis base on MATLAB/Simulink verify the charging scheme and PI controller.Finally, the primary components of the CCPS is designed and selected, then the experiments are carried out on the prototype. The theoretical analysis, the charging scheme and PI controller are experimentally confirmed.