Analysis and Design of Quasi-Z-Source Equivalent DC-DC Boost Converters

In this article, three switched-capacitor-based Zsource equivalent dc-dc boost converter (SCZEBC) topologies are proposed. The basis for these topological evolutions is the shifted L-C-D cell of the fourth-order boost converter on the front-end side, whereas a charge-pump cell on the upstream side. This hybrid combination results in quasi-Z-source equivalent dc-dc boost conversion along with enhanced voltage boosting capability. The operating duty ratio of the proposed topologies is less than 0.5 like in the conventional Z-source dc-dc converter (ZSC) topologies. In comparison to the existing Z-source topologies, remarkable features of the proposed SCZEBC topologies are: low source current ripple, common ground, and low voltage stress on capacitors and active devices. A detailed steady-state analysis is presented to identify the salient features of the proposed topologies and is thereafter compared with the existing ZSCs. Small-signal analysis is established and a voltage-mode controller is designed. In the controller design stage, a modulus margin 0.5-0.75 is adopted to ensure tradeoff between robustness and performance of the proposed converter topologies. A 48 to 220 V, 100-W prototype is built to demonstrate the effectiveness of the SCZEBC. The steady-state and closed-loop response measurements validate the theoretical studies.