A Novel Low-Loss Bidirectional T-Source Circuit Breaker with Physical Isolation for Low-Voltage DC Distribution Network

The development of low-voltage DC distribution network has advanced the research on DC circuit breakers. Compared with Z-source circuit breakers, T-source circuit breakers offer more advantages and greater research value. However, existing bidirectional Z-source and T-source circuit breakers still suffer from limitations such as high conduction loss, complex topology, and no physical isolation. Therefore, to solve these limitations, a novel low-loss bidirectional T-source circuit breaker with physical isolation is proposed in this paper. The proposed circuit breaker employs mechanical switches to reduce conduction loss, realize physical isolation, and change the power-flow direction. Since mechanical switches do not need to operate in the fault-clearing stage, the novel circuit breaker does not generate a DC arc and retains the fast self-shut-off characteristic of T-source circuit breakers. Moreover, soft-starting circuit and manual-tripping circuit are integrated into the proposed circuit breaker. Detailed analysis and design equations of the circuit breaker are provided. Finally, the capabilities of the novel circuit breaker are verified by simulation and experiment.