555 / 2017-05-14 15:02:33

Voltage Sharing Between Mechanical Switch and IGBT in Series in Hybrid Direct Current Circuit Breaker

Hybrid DC circuit breaker; voltage sharing; IGBT; parallel capacitor

Abstract: Hybrid DC circuit breakers have the advantage of fast fault current interruption with solid-state switch and low conducting loss with mechanical switch,which have broad application foreground in multi-terminal DC transmission system.The objective of this paper is to find the principle of voltage sharing between mechanical switch and IGBT in hybrid DC circuit breakers during interruption, thus, provide evidence for Hybrid DC circuit breakers to apply lower voltage IGBT to higher voltage circuit to decrease the quantity of IGBT. Compared with regular hybrid DC circuit breaker, in which IGBT and mechanical switch are in parallel, in the topology researched in this paper, IGBT and vacuum interrupter form a series circuit with a parallel capacitor . Simulation model is established. Simulation result shows that the larger parallel capacitor is, the lower voltage IGBT interrupts. A hybrid DC circuit breaker prototype is used to verify the simulation result. The voltage sharing between IGBT and mechanical switch are measured with different value of capacitor during experiments. The experiment results agree with simulation results well. As the parallel capacitor increases, the voltage applied on IGBT decreases a lot. Hence IGBT does not need to interrupts high voltage, and low rated voltage IGBT can be used, which decreases the cost of IGBT. At last the practicability of this type hybrid DC circuit breaker is discussed.