A Switched-Coupled-Inductor Quasi-Z-Source Network With High Boost Capability

This paper proposes a new high gain quasi-Z-source network (qZSN) using a two-winding switched-coupled-inductor (SCL). By employing a two-winding SCL within the impedance network, the proposed topology offers high boost capability at low shoot-through (ST) duty ratios and sub-unity windings turn ratios. Very high voltage gains (>12) are obtainable in the vicinity of the unity winding turn ratio which results in simplicity of the coupled-inductor design and reduction in the overall size. Besides, the proposed topology enjoys low voltage stresses on the switching devices. The efficiency of the proposed impedance network is considerably improved due to reducing the core and copper losses of the coupled-inductor, as well as the lower ST current stress. In addition, the proposed qZSN has a low peak magnetizing current which allows using a smaller size magnetic core for the coupled-inductor. The superiority of the proposed impedance network is confirmed by comparing with other state-of-the-art SCL-based topologies in terms of voltage gain, peak magnetizing current, total voltage stress, input current ripple, shoot-through current, and efficiency. To accurately analyze the dynamic behavior of the proposed qZSN, its small-signal model is derived using an improved circuit-averaging and averaged-switch technique. This model can then be employed to obtain the necessary transfer functions for designing the closed-loop control system. The detailed theoretical analysis and performance principles of the proposed qZSN are validated through experimental results.