A flexible control scheme for current wave forming using multiple capacitor bank units

The key issues in high power, high energy applications such as electromagnetic launchers include safety, reliability, flexibility, efficiency, compactness, and cost. To explore some of the issues, a control scheme for a large current wave-forming was designed, built and experimentally verified using a 2.4 MJ pulse power system (PPS). The PPS was made up of eight capacitors bank unit, each containing six capacitors connected in parallel. Therefore there were 48 capacitors in total, with ratings of 22 kV and 50 kJ each. Each unit is charged through a charging switch that is operated by air pressure. For discharging each unit has a triggered vacuum switch (TVS) with ratings of 200 kA and 25 kV. Hence, flexibility of a large current wave-forming can be obtained by controlling the charging voltage and the discharging times. The whole control system includes a personal computer (PC), RS232 and RS485 pseudo converter, electric/optical signal converters and eight 80C196KC microcontroller based capacitor-bank module (CBM) controllers. Hence, the PC based controller can set the capacitor charging voltages and the TVS trigger timings of each CBM controller for the current wave-forming. It also monitors and records the system status data. The RS232C and RS485 pseudo converter and electric/optical signal converters minimize the use of optical cables without reducing EMI noise immunity and reliability, this is resulting in cost reduction. This paper contains the complete control scheme and details of each subsystem unit. Some experimental current wave forming results are also included.