Three-switch topology [19].
In order to reduce cost and complexity of DCCB, two new converter configurations are proposed. These configurations deal with the unidirectional power flow and make them more suitable for the HVDC systems. The proposed configurations use less number of active switches compared to the existing ones, and thus they decrease the overall cost, control complexity and power losses. These choppers can step-up and/or step-down the transmission-level dc voltages in addition to the circuit breaker functionality. The comparison between proposed and existing DCCB's is given in Table 1. The one-switch topology saves 2412 IGBT's compared the four-switch topology and the two-switch topology saves 1608 IGBT's. The cost of one IGBT module includes the cost of itself and the control platform which produces the switching signals. The losses of one IGBT module include conduction losses and switching losses which are decided according to the curves in manufacturer's sheets and the circuit parameters. The losses of the active switches are the main losses in the IGBT-based converters [19].
Table 1.
Summary of comparison between proposed and existing DCCB's.