In applications where the high voltage gain is required, such as photovoltaic grid-connected system, fuel cell and high intensity discharge (HID) lamps for automobile, high step-up DC-DC converters have been introduced to boost the low voltage to a high bus voltage. The voltage gain of traditional Boost converter is limited considering the issues such as the system efficiency and current ripple. This paper proposes a class of hybrid switched-inductor converters for high step-up voltage gain conversion. Firstly, the topological derivation of hybrid switched-inductor converters is deduced by combining the passive and active switched-inductor unit; secondly, this paper illustrates the operation modes of the proposed asymmetrical and symmetrical converters; thirdly, the performance of the proposed converters is analyzed in detail and compared to existing converters; finally, a prototype is established in the lab, and the experimental results are given to verify the correctness of the analysis.Index Terms-Switched-inductor, high step-up, DC/DC converter.

High step-up voltage gain dc/dc converters are widely used in renewable energy power generation, uninterruptible power system, etc. In order to avoid the influence of leakage inductor in coupled inductors based converters, switched-inductor boost converter (SL-boost), switched-capacitor boost converter (SC-boost) and active-network converter (ANC) have been developed. With the transition in series and parallel connection of the inductors and capacitors, high step-up voltage conversion ratio can be achieved. This paper discusses the characteristics of the switched inductor and switched-capacitor cell; makes some comparisons between the ANC and boost converter. Based on the aforementioned analysis, this paper proposed the multicell switched-inductor/ switchedcapacitor combined active network converters (MSL/SC-ANC). The proposed converters combine the advantages of SL/SC unit and active-network structure. Compared with previous high stepup converters, the novel converter provides a higher voltage conversion ratio with a lower voltage/current stress on the power devices, moreover, the structure of proposed SL/SC-ANC is very flexible, which means the quantity of SL and SC cells can be adjusted according to required voltage gain. A 20 times gain prototype is designed as an example to show the design procedure. Theoretical analysis and experimental results are presented to demonstrate the feature of the proposed converter.Index Terms-Active network, high step-up voltage gain, multicell, switched capacitor (SC), switched inductor (SL). 0885-8993

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