Extendable Multiport High Step-Up DC-DC Converter for Photovoltaic-Battery Systems With Reduced Voltage Stress on Switches/Diodes

In the standalone photovoltaic (PV)-battery power system, a multiport converter is more desirable than several single-input converters as it has advantages of the simpler circuit, higher efficiency, and lower cost. In this article, a novel structure based on a nonisolated high step-up multiport converter (MPC) is proposed. The proposed MPC has the capability of providing high voltage gain and low normalized peak inverse voltage across semiconductor devices. Maximum power point tracking algorithm can be applied for each PV input source, which is an effective method to prevent mismatches among PV modules. Different from the existing extendable MPCs, the proposed MPC can extend both unidirectional input ports and bidirectional ports to involve more types of renewable energy sources and energy storage devices. Continuous input currents and modularity are the other profits of the proposed MPC. Various operating modes, steady-state analysis, and design considerations have been discussed. Comparison results verify the above advantage of the proposed MPC. Finally, a 240 W laboratory prototype is designed to validate the performance of the proposed MPC.