A Three-Port DC-DC Converter with Optimal Control Strategy for Spacecraft Power Systems

In spacecraft power systems, a power electronic interface is required to manage the power flow between the photovoltaic (PV) source, battery, and load. In this paper, a novel three-port converter (TPC) with optimal control strategy is proposed for this application. The proposed converter is derived by integrating an interleaved buck/boost circuit (IBBC) and a dual active bridge (DAB) circuit, which eliminates the interaction between IBBC and DAB circuit, and achieves decoupled power control between three ports. The optimal control strategy is customized in different operation modes, which widens the zero-voltage switching (ZVS) range and minimizes the inductor current stress in the transformer. In additional, a minimum competition mechanism is applied to achieve smooth and seamless transitions between different modes, so the control strategy is suitable for wide battery voltage and wide load requirements. Furthermore, the interleaved structure of IBBC reduces the input current ripple. This prolongs the lifetime of the PV panels. Finally, a 500W prototype has been built to verify the effectiveness of the proposed converter and optimal control strategy. The experimental results are consistent with the theoretical analysis.