Large Capacity Crowbar for HL-3 Fusion

Abstract

[Introduction] Facing the rapid transfer of extreme fault energy of the HL-3 fusion scientific apparatus, it is required to configure a large-capacity bypass switch for short-circuit protection. [Method] Based on the parameters of HL-3 magnet power supply, and in combination with power electronic converter technology and thyristor trigger application foundation, this paper integrated the practical experience of power electronic converter engineering, and used the following means and methods at the harsh working conditions of multi-parallel thyristor consistency conduction and stable current sharing in fast impact application: the equal length type improvement of parallel branch conductive circuit; consistency screening of parallel component parameters, differential selection of component position and parameters in parallel arm; physically forced current sharing by adding a series resistance on the side of the silicon controlled rectifier, calculation of the thermal stability of the additional resistance, and checking calculation of the electrodynamics impact of the parallel bridge arm; thyristor high-frequency pulse train strong trigger. [Result] A stable crowbar bypass protection electronic switch system for high-capacity fusion of 220 kA class of thyristor was deduced and designed, which was verified by experimental simulation and 160 kA impact test under actual load, and the matching requirements of large-capacity bypass switch for HL-3 protection were realized. [Conclusion] Under thermal and stability checking calculation, it is completely feasible to realize the matching application of large-capacity crowbar in fusion by adopting comprehensive means such as circuit improvement, additional physical force current sharing, component parameter screening and assembly, and trigger mode adjustment.

Keywords

• nuclear fusion
• thyristor
• crowbar
• protection switches
• design application