Hybrid DC Circuit Breaker Feasibility Study

Recently, a growing number of dc systems exist based on the development of electrical energy consumption. For low-voltage dc grids, switching devices are needed that have to meet technically sophisticated requirements. These devices have to handle fault currents of several hundred amperes and system voltages up to 1000 V. A typical dc circuit breaker has to provide low on-state losses, light weight, and small volume. On the way toward fulfilling these requirements, hybrid circuit breakers can represent the optimal solution. A hybrid dc circuit breaker combines the advantages of mechanical contacts and semiconductors. In this paper, such a device has been designed and constructed using a commercial switch and electronic components in the laboratory. The breaking performance of this experimental prototype has been investigated, and thus the interruption of the nominal and failure currents in the case of different time constants can be identified. The investigated hybrid switching device has been optimized in order to maximize the switching capacity and the protection of the semiconductors.