As one of the key equipments for high-voltage direct current transmission（HVDC）

DC circuit breaker hasreceived great attention. The hybrid DC circuit breaker

combining mechanical circuit breaker and solid state circuitbreaker

and exhibiting low conduction losses of mechanical circuit breaker and the high operation speed of solidstate circuit breaker

has become the main trend of DC circuit breaker research. The factors that affect forced currentcommutation DC hybrid circuit breaker based on full controlled power electronic devices opening speed are analyzedin this paper. In view of the effect on operating time of mechanical circuit breaker caused by snubber capacitor dis-charging in auxiliary current commutation circuit and the energy dissipating time of arrester

a new scheme of forcedcurrent commutation DC hybrid circuit breaker is proposed. The hybrid circuit breaker can prevent the dischargingcurrent flowing through mechanical circuit breaker

and reduce the energy dissipating time of arrester. To verify thefeasibility of the scheme

the equivalent mathematical models of different operating modes are established in this pa-per

and the simulation model of fault current breaking is conducted comparing with the typical DC hybrid circuitbreaker in Pscad/EMTDC.