High efficiency two-stage cascaded converter with energy storage device for renewable energy sources

Since photovoltaic energy sources operate at low voltage, typically boost converters are used for the high-voltage dc link. However, the high-boosted voltage causes significant power losses. This paper proposes a power-loss reduction scheme by using an energy storage connected between Boost-converter and Bidirectional-Converter in Cascade (BBCC). First stage, the boost-converter makes a voltage boosting around 100V. Because of the low voltage-rating, we can use a schottky diode for the converter. In second stage, a bidirectional-converter makes a voltage boost up to 400Vdc. Using a schottky diode and a simple bidirectional-converter can reduce the power-loss significantly. To make the output power stable, the renewable energy system needs an energy storage. Compared to conventional energy-storage systems, the proposed-system is relatively cost-effective. In this paper, the operating principle and design guidelines of the proposed scheme are presented, along with the performance analysis. Also, a 350W BBCC hardware prototype has been implemented for experimental verifications of the proposed system architecture.