A Series-Connected Half-Bridge Constant Current to Constant Voltage Converter With Full Output Power Regulation

Constant current (CC) power distribution is preferred over constant voltage (CV) power distribution in seafloor long-distance power distribution due to its fault tolerance and high system robustness. However, CC input converters differ greatly from CV input converters, especially in terms of output power regulation. In this article, a series-connected half-bridge CC/CV converter with full output power regulation is proposed. The input inductor and the switching bridge arms form a current bypass branch, which enables the charging regulation of the input port for the load change condition, to accommodate the full power range regulation. In addition, the combination of series-connected half-bridge and bus capacitors achieves controllable charging, which transforms the current source into a voltage source, and the hybrid-clamped circuit ensures mosfets voltage stress equalization. Furthermore, the chopper voltage of bridge arms combined with the midpoint of the dc bus forms the primary input of the transformer for single-stage CC/CV conversion and isolation, which simplified structure and improved efficiency. The derivation of the topology is discussed, the operation states and existing modes are analyzed. The boundaries and distributions of operation mode are discussed and illustrated. Based on the above analysis, the design guidelines considering withstanding voltage of bus capacitor are given and the control strategy is discussed. A prototype with 1A dc input and 375 V/400 W output is built to verify the feasibility of the proposed topology.