Bipolar Semiactive Bridge Converter With Cross-Cycle Modulation for Resilience Enhancement in Bipolar DC Distribution Systems

In a bipolar dc distribution system, a monopolar fault can result in a power outage for the load connected to the faulted pole. To provide a resilient load supply, a bipolar semiactive bridge (BiSAB) converter is proposed in this article as an interface converter. With the proposed BiSAB converter, the monopolar short-circuit fault can be blocked from the load, and uninterrupted power can be drawn from the normal pole. During normal bipolar operation, the BiSAB converter can also provide power regulation capability between the positive and negative poles. Moreover, the cross-cycle modulation strategy is proposed and implemented on the BiSAB to improve the efficiency in the normal bipolar mode. The characteristics and fault-tolerant function of the proposed converter and modulation strategy are verified by experiment, and the resilient load supply capability of the BiSAB is validated.