Novel three-port converter with high-voltage gain

In this paper, a novel three-port converter (TPC) with high-voltage gain for stand-alone renewable power system applications is proposed. This converter uses only three switches to achieve the power flow control. Two input sources share only one inductor. Thus, the volume can be reduced. Besides, the conversion ratio of the converter is higher than other TPCs. Thus, the degree of freedom of duty cycle is large. The converter can have a higher voltage gain for both low-voltage ports with a lower turns ratio and a reasonable duty ratio. The voltage stress of switches is low; thus, conduction loss can be further improved by adopting low R_ds(on) switches. Therefore, the converter can achieve a high conversion ratio and high efficiency at the same time. The operation principles, steady-state analysis, and control method of the converter are presented and discussed. A prototype of the proposed converter with a low input voltage 24 V for photovoltaic source, a battery port voltage 48 V, and an output voltage 400 V is implemented to verify the theoretical analysis. The power flow control of the converter is also built and tested with a digital signal processor.