Alternative Source-Port-Tolerant Series-Connected Double-Input DC–DC Converter

The two input sources of a series-connected double-input dc/dc converter (SCDIC) can power the load simultaneously or individually. But the two sources must supply the load simultaneously when the output voltage is greater than either of the two input voltages. This is a big issue, especially in double-input alternative power systems in which two input ports are, respectively, interfaced with a renewable energy source and a storage element due to the randomness and intermittency of renewable energy sources. This paper proposes a topology scheme using a combination of a charging switch and an SCDIC. In the case of one port powering or one input being short-circuit, the proposed topology forms a bootstrap circuit with the help of the charging switch and SCDIC switches to charge the powered off port and maintain the expected output voltage, which enhances the reliability of double-input conversion, making it robust against one input powering off and fault tolerance against one input short-circuit. The operation principle and the corresponding power management strategy are presented in detail. In addition, charge-discharge feature of the bootstrap mode is analyzed and the charging loss is calculated. Experimental results validate the feasibility of the proposed scheme.