A step‐up/step‐down direct current to direct current converter for high‐power, high‐current applications

Abstract

Summary This work proposes the conception of a nonisolated direct current (DC)‐DC buck‐boost converter employing the three‐state switching cell. Similarly to interleaving, it is possible to achieve higher power levels than that regarding the classical buck‐boost converter, but prominent advantages over the interleaved approach result, ie, the input current is continuous for duty ratios higher than 0.5; good current sharing is achieved without the need of special control schemes; and the active switches are connected to the same reference node as the input voltage source, as there is no need to use isolated drive circuitry. A thorough quantitative and qualitative analysis is carried for the entire range of the duty cycle D, considering that the proposed converter presents distinct behaviors for D < 0.5 and D > 0.5. An experimental prototype is developed and evaluated, while the results are discussed in detail.

Survey on topologies based on the three‐state and multi‐state switching cells

“…Even though an autotransformer is required by the 3SSC boost converter, it contributes to the achievement of natural current sharing since both magnetically coupled windings have the same impedance if the physical implementation of such magnetic element is carefully performed in practise. In this case, slight differences regarding the inductors, switches, and diodes will not cause significant current unbalance as demonstrated in [35]. This issue is not expected in interleaved converters, which are prone to current unbalance and additional thermal stress on a given phase [36].…”

“…The very same characteristics can then be addressed to the 3SSC buck–boost converter in Fig. 4 c [35, 38] and extended to other converter topologies such as Ćuk, SEPIC, and Zeta. Unfortunately, the voltage stresses regarding the aforementioned topologies are high, i.e.…”