Fully Soft-Switched High Step-Up Quasi Z-Source Converter With Controllable Duty Cycle Range

This article proposes a new high step-up converter based on the quasi Z-source (qZs) structure. By applying high step-up techniques and active clamp cell to the basic converter, high voltage gain, very low switch voltage stress, and fully soft switching operation are realized. The proposed converter benefits from controllable duty cycle range achieved by coupled inductors to facilitate the qZs converters limitation. Therefore, by expanding the duty cycle range, more efficient operating points are provided for a particular application and solves the regulation difficulty at high voltage gains. Besides, the switches are turned on at ZVZCS, and capacitive turn-on losses are eliminated while all diodes turn-off without the reverse recovery loss. Due to the mentioned features, this converter can achieve high efficiency. Moreover, the presented converter has continuous input current with low ripple and common ground between the input and output which expands its applicability. The converter operation is fully investigated and to validate the theoretical analysis, a 200W prototype is implemented in the laboratory.