单开关软开关高升压直流-直流变换器及其降低的电压应力

A soft-switched nonisolated dc–dc high step-up converter with a single switch is proposed in this article, which can be applied in photovoltaic systems. To achieve high voltage gain and reduce the components voltage stress, coupled inductors and switched capacitor techniques are integrated. A suitable lossless snubber circuit overcoming the lossless snubber challenges such as high component count and freewheeling conduction loss is employed to alleviate the switching losses along with the diodes reverse recovery problems. The lossless snubber circuit adds only two diodes to the proposed structure which is optimum in terms of component count among the soft-switching circuits. Using only one switch with reduced voltage stress and simple passive lossless snubber has contributed to the converter efficiency improvement and reduced control circuit complexity. Furthermore, the input current of the proposed converter is continuous, which facilitates the maximum power point tracking (MPPT) realization and enhances the converter performance. A complete analysis is provided to verify the converter operation, and a 200 W laboratory prototype with an input voltage range of 20 to 30 V and a fixed output voltage of 200 V, is implemented to verify the theoretical analysis. Also, a comprehensive comparison between the proposed and comparative topologies is described to illustrate the converter superiority.