Transformerless quadratic‐based high step‐down DC–DC converter with wide duty cycle range

Abstract

In this study, a quadratic‐based transformerless high step‐down DC‐DC buck converter is presented. There are two switching patterns applied to the switches. Through the first switching pattern, the proposed converter provides a constant step‐down voltage conversion ratio for the whole ranges of duty cycles. On the other hand, by using an interleaved switching pattern for the proposed converter the input voltage will be divided equally between the primary capacitors, as a result, low voltage stress will be across the semiconductor components. This feature allows the designer to select switches and diodes with lower voltage ratings. However, with the interleaved switching pattern, the converter will have two different voltage conversion ratios for duty cycles larger and less than 0.5. Furthermore, the proposed converter is capable of providing a high range of currents without applying extremely narrow duty ratios. Theoretical analysis is provided in this study. To show the merits of the proposed converter, it is compared with other similar recently presented converters. A 430 W prototype of the proposed converter with 600 V/20 V is implemented and experimental results are presented and compared with the theoretical ones.