Design of a high current protection inductor for the high energy density capacitor bank of large laser fusion facility

Abstract

High energy density capacitor banks are used in pump power supplies of the laser fusion facility. The capacitor bank works in the state of high voltage and enormous energy, so it is vital to protect the capacitor bank from faults, especially capacitor internal insulation breakdown. In that case, the discharge circuit will be a huge short-circuit current and cause serious structure and fire damage to the capacitor and nearby components. In this paper, a protection inductor is designed to protect the capacitor bank applied to the 100 kA/1 MJ discharge condition. The solenoid inductor coil is made of manganin wire and installed in the epoxy resin cylinder. The design process of the coil is simplified by using the material with low temperature coefficient of resistance, and the design method of inductor parameters is presented based on temperature constraint. It is found that the von Mises stress in the designed inductor is below the ultimate tensile strength of the materials by finite element simulation. A simulated fault current discharge platform was built to test the inductor, and the inductor keeps structure integrity after the test. The inductor design method can provide guidance for the protection design of the capacitive power supply system.