Abstract：In view of the problem that the transfer branch of the current high-voltage DC circuit breaker mostly

adopts uncontrollable full-bridge transformer coupling energy supply，which is not conducive to controllable and

stable power supply，and low energy utilization，a combined DC circuit breaker energy supply method was

proposed. A bidirectional DC-DC converter topology with energy storage device（battery or super capacitor）was

used to control the voltage control and energy recovery and reuse of the precharged capacitor in the resonant

transfer branch of the combined DC circuit breaker. A control strategy for DC-DC energy supply using dual-activebridge（DAB）was developed as an example. The improved energy mode of supply can not only ensure the fast and stable supply of transferred branch energy during the rapid opening of the combined high-voltage DC circuit breaker in the event of DC power grid failure，but also use the recovered energy for the reclosing process after fault recovery. The simulation and experimental results show that the proposed bidirectional DC-DC converter replaces the uncontrollable full-bridge combined high-voltage DC circuit breaker energy supply method，and the output voltage is more stable，and the energy utilization rate of the system is improved.

      Key words：DC circuit breaker；energy supply；fault breaking；dual-active-bridge（DAB）converters