In this study, a new three-level boost converter is introduced which has high voltage gains suitable for photovoltaic applications. Three-level structure has the advantage of low voltage stresses of the switches and diodes. In the proposed converter, semiconductor devices operate under soft-switching conditions which results in low switching losses. It utilises an active clamp circuit with one auxiliary switch to absorb the leakage energy. Therefore, elimination of the voltage spikes across the switches as well as efficiency improvement is achieved. On the other hand, the proposed converter has one magnetic core, and consequently, reduced size. Operating principles of the proposed converter along with its theoretical analysis are presented. Experimental results of a 200 W laboratory prototype for voltage conversion of 40 V/400 V are provided in order to verify the proposed converter performance.
Here, a soft switched three-level boost converter with high voltage gain is proposed which is suitable for high step-up applications with wide output power range. In this converter, a ZVT auxiliary circuit is used which provides soft switching in a wide range of output power independent of load variation. Utilizing coupled-inductors with one magnetic core removes extra auxiliary core in the soft switching circuit and provides high voltage gain in conjunction with size reduction. Also, the secondary and tertiary leakage inductances of the coupled-inductors minimize the reverse recovery problem of the output diodes. Due to its three-level structure, it has very low voltage stress over semiconductor elements in comparison to the existing interleaved structures, resulting in using MOSFETs with low on-resistance and thus lower conduction losses and cost. Operating modes as well as analytical analysis of the proposed converter are discussed. Finally, in order to validate the proposed converter performance, experimental results from a 200-W laboratory prototype are presented.How to cite this article: Jazi, H.M., Fekri, M., Keshani, M., et al.: Soft-switching non-isolated high step-up three-level boost converter using single magnetic element.
In this paper a novel soft switched interleaved boost structure with a simple auxiliary circuit is proposed which is suitable for stand-alone loads or AC grid applications. In this topology, coupled inductors and switched capacitor cells of parallel modules are merged to obtain high voltage conversion ratio. The converter also has the capability of adding extra switched capacitor cells to attain very high voltage gain. In order to provide soft switching condition in the wide range of output power, a new ZVT auxiliary circuit is employed which is responsible for soft switching of both phases and benefits from low conduction losses, the minimum number of semiconductor elements and only one auxiliary gate driver. These merits provide very high efficiency at both full load and light loads. More importantly, no auxiliary magnetic components are utilized by taking advantage of the leakage inductance of coupled inductors for the resonant network. All semiconductor components operate under soft switching alleviating the reverse recovery problem and switching losses. Besides, the converter benefits from common ground between input and output which simplify voltage feedback. The experimental results of the converter prototype with 400 V output voltage at 400 W are provided, which verify the advantages of the proposed approach.
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