A simple and useful three-port converter for integrating renewable energy sources in stand-alone systems

A simple and useful three-port converter is proposed in this paper, which is suitable for integrating renewable energy sources in off-grid applications with low to medium power. It mainly consists of a coupled inductor and two active switches. Isolation between the two renewable energy sources is achieved. Only one active switch functions in either loading mode or battery-charge mode. Hence the switching losses is reduced. Output diode of the proposed converter is removable from the system if one of the power source is integrated inside with anti-reversed-current diode, so that the system overall cost is reduced. Easy control techniques can be applied to the converter, since power decoupling control is not necessary due to the limited power provided by a single PV panel. A 110W experimental prototype with two inputs (30V, 24V) and 80V output, was built and tested under loading mode and battery-charge mode to validate the theoretical analysis. Examine of adding active snubber to eliminate voltage spike on the switches is introduced in the simulation.