A non‐isolated DC‐DC converter with low voltage stress and high step‐down voltage conversion ratio

Abstract

This work focuses on a new non-isolated interleaved DC-DC converter with very high step-down voltage conversion ratio. By employing the switched/series capacitor concept, along with the proper component interconnection, the converter features a high step-down voltage conversion ratio where, in the private case of equal duty ratios, it is six times higher than the conventional buck converter. This high step-down voltage conversion ratio is achieved with the lowest number of components compared to other similar topologies of the same conversion ratio. Also, due to the blocking/series capacitors, the voltage stress on the switches is reduced, improving the converter efficiency. One of the key features of the proposed converter is the inherent automatic current sharing between the interleaved phases, which in the case of equal duty ratios, is uniformly distributed. To add on, due to the use of only two interleaved phases, the converter has a wide output voltage range, since the duty cycle can be extended to 0.5. To validate the proposed converter operation, a 250 W wide-input/wide-output experimental prototype was built, achieving a peak efficiency of 94%.