Series-connected insulation gate bipolar transistors（IGBTs） are applied to withstand the turnoff overvoltage in DC micro-grid hybrid circuit breaker. Thus

we investigated the series dynamic voltage-sharing of IGBTs. Firstly

we analyzed the causes of uneven dynamic voltage-sharing of IGBTs and the principle of RCD（resistor

capacitor

diode） snubber circuit. Then

we analyzed the voltage-sharing characteristic

overvoltage and turnoff loss of IGBTs

reverse voltage of diodes under different RCD circuit parameters by simulation. Finally

the 1.2 kV/2.4 kV power electronics interrupting unit with IGBTs in series was set up for verification. The short circuit current was 600 A

and the time difference between turn-off signals was 500 ns. The research indicates that

the larger the buffer capacitance in a certain range is

the smaller the overvoltage and turn-off loss of IGBTs will be

and the better the voltage-sharing will be; however

the excessive capacitance has a limited effect on the reduction of them. The larger the buffer resistance in a certain range is

the better the suppression of damped oscillation after turnoff of arrester will be; however

the reverse voltage of diodes will increase. The combined results of simulation and experiments show that the optimal circuit parameters of 2～3 μF buffer capacitance and 2 Ω buffer resistance are proposed

by which the principle of diode selection is given. The voltage-sharing characteristics of RCD snubber circuit are verified by investigation

which provides the technical reference for application in DC breaking.