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

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.