Novel dc/dc choppers with circuit breaker functionality for HVDC transmission lines

• Proposed two converter topologies used as dc circuit breakers for HVDC transmission.
• Proposed configurations are promising for future practical development as they are less costly.
• Proposed auxiliary controller ensures the short-circuit faults shut-down completely.
• An isolation time of 6.5 ms has been achieved by proposed controller.
• The proposed circuit breaker can switch between step-up and step-down modes smoothly.

This paper proposes two novel dc/dc choppers with dc circuit breaker functionality for HVDC transmission lines. These converters feature step-up and/or step-down functions with instant interruption of short-circuit faults. Compared to other state-of-the-art converter topologies described in the literature, the proposed topologies have better control functions, lower manufacturing costs and reduced energy losses. A double closed-loop controller is designed to regulate the inductor current and output voltage of the converters. An auxiliary controller is also proposed to ensure proper shut-down of the circuit breaker in the event of dc short-circuit faults. The simulation and experimental results are presented to validate the effectiveness of the proposed converter configurations and control scheme.