Tail Current Transfer Strategy for Self-triggered Low-voltage Hybrid DC Circuit Breakers

Low-voltage hybrid DC circuit breakers, with their low conduction losses, high interruption capabilities, and selective protection, constitute a key direction for the development of DC interruption technology. To meet the application demands for large-capacity interruption, it is essential to further enhance their working reliability. Firstly, this paper analyzes the interruption characteristics of a self-triggered low-voltage hybrid DC circuit breaker under different short-circuit conditions. To address the issue of pronounced current tailing at high voltage levels, a current transfer strategy based on the desaturation detection circuit is proposed. This strategy enables the protection circuit to operate periodically without external sensors, thereby maximizing the current-carrying capacity of the device. By integrating the temperature rise assessment method based on the Foster thermal network model, a design method for optimal timing coordination between mechanical and electronic systems is established. Finally, experimental results indicate that compared with mechanical circuit breakers, hybrid interruption technology can effectively reduce arc duration and arc energy. The current transfer strategy proposed in this paper can significantly shorten the duration of the tail current and is applicable. The research results provide important references for the design optimization and performance improvement of low-voltage hybrid DC circuit breakers.