The Development Of High Current Full-controlled Solid-State Circuit Breaker For EAST Fusion Device

The Expermental Advanced Superconduting Tokamak(EAST)device is a major scientific project in the Ninth Five-Year Plan of China,which provides an important engineering and physical experimental basis for future fusion experimental reactor.Switching Network Unit(SNU)is one of the key components of EAST device to initialize the plasma.Based on the design requirement rated for the current of 15 kA and breaking voltage of 2.0 kV,a bidirectional H-bridge Solid-State Circuit Breaker(SSCB)based on multiparallel IGCT device is developed.Compared with the dc SSCB based on thyristor technology,the bidirectional H-bridge SSCB has the advantages of fast bidirectional interruption,convenient maintenance and small floor area.The main contents and innovations of this paper are as follows:By deeply studied on the commutation process of the SNU based on bidirectional H-bridge SSCB,the design solution of the electrical parameters for commutation circuit is proposed.The reverse peak overvoltage problem of the IGCT devices during the fast turn-off process,and the oscillation of the common diode components during the reverse recovery process are optimized and solved.The symmetrical modular structure of bidirectional H-bridge SSCB is designed.The main influencing factors of dynamic and static current sharing between parallel power components are analyzed,and the effect of stray parameters on dynamic and static current sharing in the parallel components structure is detailed analyzed.Based on the establishment of parallel power module structure and circuit model,the joint simulation analysis of circuit and structure was carried out.By continuously optimizing the structure and improving the stray distribution parameters in the circuit,the dynamic and static current sharing between eight parallel IGCT devices was successfully solved.The test results verify the correctness of the simulation analysis process and the rationality of the parallel component structure.This simulation model provides important engineering guidance for the structure and the dynamic and static current sharing design of the parallel components.According to the characteristics of the high power loss of the bi-directional H-bridge SSCB,firstly,the total power loss of the power devices is reduced by improving and optimizing the process.At the same time,the flow channel structure model of the water-cooled heat sink in the power parallel module is deeply studied,and the heat dissipation performance of two water-cooled heat sinks with different tube structures was compared and analyzed.Finally,based on the above model,a water-cooled heat sink with double-layer Archimedes spiral tube structure is proposed to solve the thermal stability problem of power devices under high current operation.Its low thermal resistance reduces the parallel number of the power devices and the difficulty of the parallel structure design.A DC full-controlled bidirectional H-bridge SSCB with a rated current of 15 kA and breaking voltage of 2 kV was developed.The rapid bidirectional breaking under rated current was realized by rountine and type tests.and the current sharing coefficient between parallel IGCT components was more than 0.9.The reliability and feasibility of the SSCB design solution are verified by the simulation analysis and test results.