Research On Full-bridge Multi-port Converters Based-on Active Boost Rectification

A renewable power system, which usually consists of energy source, storage element and load, can be considered as a three-port power system with the input, output and bidirectional ports. The conventional solution of multiple separate converters can be replaced by a integrated multi-port converter(MPC), which features reduced size, lower cost and better efficiency and compact centralized control. Based on this, a novel kind of MPC with active boost rectifier(ABR) was researched in this paper.The MPCs researched in this paper are derived by integrating two interleaved Buck/Boost circuits(IBBC) and a FBC with ABR, while the ABR can be full-bridge or voltage-doubler(VD) structure. Firstly, two kinds of three-port converter, which is called full-bridge ABR-TPC and VD-ABR-TPC, have been researched. Operation modes, working states, output characteristics and soft switching were analyzed in detail, then the design considerations were given and prototypes were built to verify the analysis, respectively. Theoretical analysis and experimental results demonstrate that the two TPCs mentioned above can achieve high-efficiency single-stage conversion between any two of the three ports, while soft-switching of all the active switches and diodes can be realized in a wide load range. Furthermore, with the PWM plus secondary-side phase-shift control scheme, the range of the output voltage gain can be enlarged, which is suitable for the applications with fluctuant voltages of renewable energy generation devices or storage elements. Secondly, a four-port converter(FPC) with two independent output ports was researched, which is composed of the two TPCs studied above. The characteristics of the FPC are similar to the two aforementioned TPCs. A novel power management strategy based on parallel competition was designed to meet the different requirements of the various power ports. Finally, a prototype of the FPC was built to verify the topology and power control. Experimental results show that high-efficiency conversion can be achieved. With the power management, maximum power point tracking(MPPT) of PV panel, maximum current or maximum voltage charging of the battery and independent power control of the two output ports can be realized simultaneously, which satisfy the requirements of stand-alone renewable power systems.