A Bidirectional Thyristor-Based DC Circuit Breaker With an RC Auxiliary Circuit

DC circuit breakers (DCCBs) are increasingly used for protecting dc grids, with many conventional designs relying on auxiliary circuits—such as LC, RC, and coupling inductance circuits—to interrupt the main circuit. Compared to the DCCBs using other auxiliary circuits, the DCCBs with RC auxiliary circuits are generally simpler due to straightforward parameter design. Therefore, a new bidirectional thyristor-based DCCB with an RC auxiliary circuit is proposed, offering low conduction losses in the main branch, simplified capacitor precharging, and reliable current interruption capabilities. Besides, the contacts of the mechanical switch can be separated under both zero-current switching and zero-voltage recovery conditions, which can enhance the safety of the protection process. Moreover, compared to the existing DCCB with RC auxiliary circuits, the proposed scheme introduces a new operating method to further reduce capacitor costs. In addition, it employs the same operation sequences for bidirectional protection. Finally, the parameter design is analyzed to ensure the performance of the proposed DCCB, and a small-scale experimental platform is constructed to verify its functionality.