Being advantageous for long-distance power transmission and new energy connection, DC system has wide range of applications in many scenarios. As the capacity of DC power grids increases, the fault current is more difficult to interrupt. And the DC circuit breaker which is very important for protecting DC grid attracts more and more attention of researchers. In this paper, a new hybrid DC circuit breaker topology based on the technique of thyristor forced current zero is proposed. The breaker

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... able to interrupt the fault current in several milliseconds, and the mechanical switch can be cut off at zero current. In addition, no extra power supply and control devices are needed, the pre-charging capacitor can obtain energy from DC grid directly. Therefore, the control process is simpler and the reliability is greatly improved. The operating principle of the proposed circuit breaker is analyzed in detail, and then the simulation is carried out in PSCAD/EMTDC which verifies the correctness of the theoretical analysis and the feasibility of the breaker.